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Background Environmental disinfection is essential for reducing spread of healthcare-associated infections (HAIs). Previous studies report conflicting results regarding the effects of ultraviolet (UV) light in reducing infections. This trial evaluated the impact of adding pulsed-xenon UV (PX-UV) to standard terminal cleaning in reducing environmentally implicated HAIs (eiHAIs). Methods The Lowering the Acquisition of MDROs with Pulsed-xenon (LAMP) trial was conducted in 2 hospitals (15 inpatient wards) utilizing a cluster-randomized, controlled, double-blinded, interventional crossover trial comparing standard terminal cleaning followed by either PX-UV (intervention arm) or sham (control arm) disinfection. The primary outcome was incidence of eiHAIs from clinical microbiology tests on the fourth day of stay or later or within 3 days after discharge from the study unit. EiHAIs included clinical cultures positive for vancomycin-resistant enterococci, extended-spectrum beta-lactamase–producing Escherichia coli or Klebsiella pneumonia , methicillin-resistant Staphylococcus aureus , and Acinetobacter baumannii , and stool polymerase chain reaction (PCR) positive for Clostridiodes difficile. Results Between 18 May 2017 and 7 January 2020, 25 732 patients were included, with an incidence of 601 eiHAIs and 180 954 patient-days. There was no difference in the rate of eiHAIs in the intervention and sham arms (3.49 vs 3.17 infections/1000 patient-days, respectively; RR, 1.10; 95% CI,.94–1.29; P =.23). Study results were similar when stratified by eiHAI type, hospital, and unit type. Conclusions The LAMP study failed to demonstrate an effect of the addition of UV light disinfection following terminal cleaning on reductions in rates of eiHAIs. Further investigations targeting hospital environmental surfaces and the role of no-touch technology to reduce HAIs are needed. Clinical Trials Registration. ClinicalTrials.gov identifier: NCT03349268; R01HS024709. [ABSTRACT FROM AUTHOR]

Aims In Tunisia, limited research has focused on characterizing clinical vancomycin-resistant Enterococcus faecium (VREfm). This study aimed to bridge this knowledge gap by molecular characterization of antimicrobial resistance, determining the genetic elements mediating vancomycin-resistance, and whole-genome sequencing of one representative VREfm isolate Methods and results Over 6 years (2011–2016), a total of eighty VREfm isolates responsible for infection or colonization were identified from hospitalized patients, with the incidence rate increasing from 2% in 2011 to 27% in 2016. All of these strains harbored the vanA gene. The screening for antimicrobial resistance genes revealed the predominance of ermB, tetM , and aac(6′)-Ie-aph(2′')-Ia genes and 81.2% of strains harbored the Tn 1545. Pulsed-field gel electrophoresis identified seven clusters, with two major clusters (belonging to ST117 and ST80) persisting throughout the study period. Seven Tn 1546 types were detected, with type VI (truncated transposon) being the most prevalent (57.5%). Whole-genome sequencing revealed a 3 028 373 bp chromosome and five plasmids. Mobile genetic elements and a type I CRISPR-cas locus were identified. Notably, the vanA gene was carried by the classic Tn 1546 transposon with ISL3 insertion on a rep17pRUM plasmid. Conclusion A concerning trend in the prevalence of VREfm essentially attributed to CC17 persistence and to horizontal transfer of multiple genetic variants of truncated vanA -Tn 1546. [ABSTRACT FROM AUTHOR]

Aims To investigate enterococci carrying linezolid and vancomycin resistance genes from fecal samples recovered from wild boars Methods and results Florfenicol- and vancomycin-resistant enterococci, isolated on selective agar plates, were screened by PCR for the presence of linezolid and vancomycin resistance genes. Five isolates carried optrA or poxtA linezolid resistance genes; one strain was resistant to vancomycin for the presence of vanA gene. All isolates were tested for their antibiotic susceptibility and subjected to Whole Genome Sequencing (WGS) analysis. In Enterococcus faecalis (E. faecalis) V1344 and V1676, the optrA was located on the new pV1344-optrA and pV1676-optrA plasmids, respectively, whereas in Enterococcus faecium (E. faecium) V1339 this gene was on a 22 354-bp chromosomal genetic context identical to the one detected in a human E. faecium isolate. In both E. faecium V1682 and E. durans V1343, poxtA was on the p1818-c plasmid previously found in a human E. faecium isolate. In E. faecium V1328, the vanA gene was on the Tn 1546 transposon in turn located on a new pV1328-vanA plasmid. Only E. faecium V1682 successfully transferred the poxtA gene to an enterococcal recipient in filter mating assays. Conclusions The occurrence of genetic elements carrying linezolid and vancomycin resistance genes in enterococci from wild boars is a matter of concern, moreover, the sharing of plasmids and transposons between isolates from wild animals, human, and environment indicates an exchange of genetic material between these settings. [ABSTRACT FROM AUTHOR]

Background Epidemiologic studies have shown decreasing vancomycin susceptibility among clinical Clostridioides difficile isolates, but the impact on patient outcomes is unknown. We hypothesized that reduced vancomycin susceptibility would be associated with decreased rates of sustained clinical response (SCR). Methods This multicenter cohort study included adults with C. difficile infection (CDI) treated with oral vancomycin between 2016 and 2021. Clostridioides difficile isolates underwent agar dilution vancomycin susceptibility testing, ribotyping, and Sanger sequencing of the vancomycin resistance vanR gene. Reduced susceptibility was defined as vancomycin minimum inhibitory concentration (MIC) >2 μg/mL. The primary outcome was 30-day SCR; secondary outcomes were 14-day initial cure, 30-day recurrence, and 30-day mortality. Exploratory analysis assessed the association between the VanR Thr115Ala polymorphism, susceptibility, and outcomes. Results A high proportion (34% [102/300]) of C. difficile isolates exhibited reduced vancomycin susceptibility (range, 0.5–16 μg/mL; MIC50/90 = 2/4 μg/mL). Ribotype 027 accounted for the highest proportion (77.4% [41/53]) of isolates with reduced vancomycin susceptibility. Overall, 83% (249) of patients achieved 30-day SCR. Reduced vancomycin susceptibility was associated with lower rates of 30-day SCR (76% [78/102]) than vancomycin-susceptible strains (86% [171/198]; P =.031). A significantly lower rate of 14-day initial cure was also observed among individuals infected with strains with reduced vancomycin susceptibility (89% vs 96%; P =.04). Reduced susceptibility remained an independent predictor of 30-day SCR in multivariable modeling (odds ratio, 0.52 [95% confidence interval,.28–.97]; P =.04). Conclusions Reduced vancomycin susceptibility in C. difficile was associated with decreased odds of 30-day SCR and lower 14-day initial cure rates in the studied patient cohort. [ABSTRACT FROM AUTHOR]

Background The glycopeptide vancomycin is the antimicrobial agent-of-choice for the treatment of severe non-gastrointestinal infections with members of Bacillus cereus sensu lato (s.l.). Recently, sporadic detection of vancomycin-resistant phenotypes emerged, mostly for agar diffusion testing such as the disc diffusion method or gradient test (e.g. Etest®) method. Results In this work, we were able to disprove a preliminarily assumed high resistance to vancomycin in an isolate of B. cereus s.l. using broth microdilution and agar dilution. Microscopic imaging during vancomycin susceptibility testing showed spreading towards the inhibition zone, which strongly suggested sliding motility. Furthermore, transcriptomic analysis using RNA-Seq on the nanopore platform revealed several key genes of biofilm formation (e.g. calY , tasA , krsEABC) to be up-regulated in pseudo-resistant cells, substantiating that bacterial sliding is responsible for the observed mobility. Down-regulation of virulence (e.g. hblABCD , nheABC , plcR) and flagellar genes compared with swarming cells also confirmed the non-swarming phenotype of the pseudo-resistant isolate. Conclusions The results highlight an insufficiency of agar diffusion testing for vancomycin susceptibility in the B. cereus group, and reference methods like broth microdilution are strongly recommended. As currently no guideline mentions interfering phenotypes in antimicrobial susceptibility testing of B. cereus s.l. , this knowledge is essential to obtain reliable results on vancomycin susceptibility. In addition, this is the first report of sliding motility undermining accurate antimicrobial susceptibility testing in B. cereus s.l. and may serve as a basis for future studies on bacterial motility in susceptibility testing and its potential impact on treatment efficacy. [ABSTRACT FROM AUTHOR]

The Antibacterial Resistance Leadership Group (ARLG) has prioritized infections caused by gram-positive bacteria as one of its core areas of emphasis. The ARLG Gram-positive Committee has focused on studies responding to 3 main identified research priorities: (1) investigation of strategies or therapies for infections predominantly caused by gram-positive bacteria, (2) evaluation of the efficacy of novel agents for infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci, and (3) optimization of dosing and duration of antimicrobial agents for gram-positive infections. Herein, we summarize ARLG accomplishments in gram-positive bacterial infection research, including studies aiming to (1) inform optimal vancomycin dosing, (2) determine the role of dalbavancin in MRSA bloodstream infection, (3) characterize enterococcal bloodstream infections, (4) demonstrate the benefits of short-course therapy for pediatric community-acquired pneumonia, (5) develop quality of life measures for use in clinical trials, and (6) advance understanding of the microbiome. Future studies will incorporate innovative methodologies with a focus on interventional clinical trials that have the potential to change clinical practice for difficult-to-treat infections, such as MRSA bloodstream infections. [ABSTRACT FROM AUTHOR]

Background The long-standing antimicrobial resistance (AMR) pandemic has proven difficult to resolve and is becoming more complex, especially in the context of increasing forced migration, with little evidence around patterns of AMR in migrant communities. This study aimed to determine the frequency in the carriage of common types of antimicrobial-resistant bacteria between Syrian refugees and the local communities in Türkiye: extended-spectrum β-lactamase (ESBL), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Methods We collected nasal swabs and stool samples from the study participants, the local community members, and refugees, between September 2020 and March 2021. We screened clinical samples for the presence of ESBL, MRSA and VRE. Antimicrobial-resistant bacterial isolates were tested by phenotypic analysis to determine the AMR status. Results The study included a total of 3960 participants: 1453 individuals in the local community (36.2%) and 2525 Syrian refugees (63.8%). Overall, a significantly greater proportion of refugees (6.7%) carried MRSA compared to the local community (3.2%) (P  < 0.001). The ESBL-positivity rate was 17.9% in Syrian refugees and 14.3% in the local community (P  = 0.041). Carbapenemase activity was detected in three isolates from Syrian refugees. No VRE was detected in Syrian refugees or the local community. Conclusions This large, community-based study on the frequency and the distribution of AMR among Syrian refugees and the local population is the first study in Türkiye. [ABSTRACT FROM AUTHOR]

Enterococci are commensals of the human intestinal tract. Their use as probiotics is supported by their ability to confer several health benefits and eliminate foodborne pathogens but is controversial due to the presence of virulence and antibiotic resistance traits. To use them as probiotics requires thorough research to establish their safety. Here, we sequenced the whole genome of a newly isolated Enterococcus durans MN187066 and used a suite of bioinformatics tools to analyze its beneficial probiotic traits as well as antimicrobial resistance and virulence genes. The whole genome had a length of 2   978 152 bp, and an average G + C content of 37.88%. The bopABCD genes involved in biofilm formation were annotated in the genome. However, further analysis showed that these genes are mostly helpful in strengthening their colonization and establishment in the gastrointestinal tract. Also, we identified secondary metabolite gene clusters and the bacteriocins Enterolysin A and Enterocin P. We also identified repUS15 and rep1 replicons and genes that were associated with antimicrobial resistance and virulence. Nevertheless, vancomycin resistance genes were not detected. Our results show that the Ent. durans strain MN187066 can be considered a nontoxigenic strain and produces beneficial metabolites that are critical for their success as probiotics. [ABSTRACT FROM AUTHOR]

Objectives The clinical significance of rifampicin resistance in Staphylococcus aureus infections has not been demonstrated. Here, we evaluated the clinical characteristics of rifampicin-resistant S. aureus infection. Methods Data were collected from adult patients who were hospitalized with MRSA bacteraemia between March 2007 and May 2020 at a tertiary hospital in South Korea. The clinical characteristics and treatment outcomes of patients infected with rifampicin-resistant MRSA were compared with those of rifampicin-susceptible isolates. All-cause death and recurrence of MRSA infection were assessed for 90 days. Results Of the 961 patients with MRSA bacteraemia, 61 (6.3%) were infected by rifampicin-resistant isolates. The type of infection focus and duration of bacteraemia did not significantly differ between the two groups. Rifampicin-resistant MRSA isolates were more likely to have multidrug resistance and a higher vancomycin MIC relative to the rifampicin-susceptible isolates. The 90-day recurrence rate was higher in the patients infected with rifampicin-resistant MRSA compared with those with rifampicin-susceptible MRSA (18.0% versus 6.2%, P  < 0.001), whereas the 90-day mortality was comparable between the two groups (27.9% versus 29.2%, P  = 0.94). After adjusting for potential confounding factors, rifampicin resistance was significantly associated with 90-day recurrence (subdistributional HR: 2.31; 95% CI: 1.05–5.10; P  = 0.04). Conclusions Rifampicin-resistant MRSA isolates showed distinct microbiological features in terms of multidrug resistance and a high vancomycin MIC. Although the management of MRSA bacteraemia was not significantly different between the two groups, recurrence was significantly more common in the rifampicin-resistant group. Rifampicin resistance may play a significant role in infection recurrence. [ABSTRACT FROM AUTHOR]

Background Vancomycin and linezolid resistance among enterococci is an increasing problem due to a lack of alternative antibiotics. Early identification of vancomycin-resistant and linezolid-resistant strains can help prevent the spread of resistance to these antibiotics. Hence, early, rapid and accurate detection of vancomycin and linezolid resistance is critical. Objectives The resazurin microplate method (RMM) was developed for detecting vancomycin and linezolid susceptibility among Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) clinical isolates, and its performance was further evaluated. Methods A total of 209 non-duplicate clinical isolates and three strains from the faeces of domestic animals, including 142 E. faecalis (71 linezolid non-susceptible and 71 linezolid susceptible) and 70 E. faecium (23 vancomycin non-susceptible, 23 vancomycin susceptible, 12 linezolid non-susceptible and 12 linezolid susceptible), were tested using RMM. Results The susceptibility of E. faecium to vancomycin was detected within 5 h, with high susceptibility (23/23) and specificity (23/23). The susceptibility of E. faecalis and E. faecium to linezolid was detected within 4 h, with specificities of 98.59% and 100% and susceptibilities of 94.37% and 58.33% for E. faecalis and E. faecium , respectively. Conclusions RMM had a good positive predictive value for the detection of vancomycin-non-susceptible E. faecium and linezolid-non-susceptible E. faecalis. It thus has the potential to become an alternative method for the rapid screening of these resistant pathogens in clinical practice. [ABSTRACT FROM AUTHOR]

Background: Heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) compromise the clinical efficacy of vancomycin. The hVISA isolates spontaneously produce vancomycin-intermediate Staphylococcus aureus (VISA) cells generated by diverse and intriguing mechanisms.Objective: To characterize the biomolecular profile of clinical hVISA applying genomic, transcriptomic and metabolomic approaches.Methods: 39 hVISA and 305 VSSA and their genomes were included. Core genome-based Bayesian phylogenetic reconstructions were built and alterations in predicted proteins in VISA/hVISA were interrogated. Linear discriminant analysis and a Genome-Wide Association Study were performed. Differentially expressed genes were identified in hVISA-VSSA by RNA-sequencing. The undirected profiles of metabolites were determined by liquid chromatography and hydrophilic interaction in six CC5-MRSA.Results: Genomic relatedness of MRSA associated to hVISA phenotype was not detected. The change Try38 → His in Atl (autolysin) was identified in 92% of the hVISA. We identified SNPs and k-mers associated to hVISA in 11 coding regions with predicted functions in virulence, transport systems, carbohydrate metabolism and tRNA synthesis. Further, capABCDE, sdrD, esaA, esaD, essA and ssaA genes were overexpressed in hVISA, while lacABCDEFG genes were downregulated. Additionally, valine, threonine, leucine tyrosine, FAD and NADH were more abundant in VSSA, while arginine, glycine and betaine were more abundant in hVISA. Finally, we observed altered metabolic pathways in hVISA, including purine and pyrimidine pathway, CoA biosynthesis, amino acid metabolism and aminoacyl tRNA biosynthesis.Conclusions: Our results show that the mechanism of hVISA involves major changes in regulatory systems, expression of virulence factors and reduction in glycolysis via TCA cycle. This work contributes to the understanding of the development of this complex resistance mechanism in regional strains. [ABSTRACT FROM AUTHOR]

Objectives: Since 2003, incidences of carbapenemase-producing Gram-negative bacilli (CP-GNB) and vancomycin-resistant Enterococcus faecium (VRE) have steadily increased in France. We therefore conducted a point prevalence study to estimate carriage rates of CP-GNB, VRE and ESBL-producing Enterobacterales (ESBL-PE) and associated risk factors.Methods: Between September 2019 and January 2020, all inpatients hospitalized on a given day in 11 teaching hospitals in the Paris urban area were eligible. Patient interviews and rectal swab screening results were recorded by dedicated nurses. The swabs were plated onto selective chromogenic media and processed using the GeneXpert® system.Results: Of 2396 patients, 364 (15.2%) yielded at least one multiresistant bacterial isolate, including 29 CP-GNB carriers (1.2%), 13 VRE carriers (0.5%) and 338 ESBL-PE carriers (14%). In 15 patients (4.4% of ESBL-PE carriers and 36.6% of CP-GNB/VRE carriers), concomitant CP-GNB/VRE and ESBL-PE carriage was observed. In 7/29 CP-GNB and 7/13 VRE carriers, carbapenemase production and vanA in the screening samples was only detected with Xpert® tests. The OXA-48 gene was predominant in 13/34 CP-GNB isolates from 29 carriers. From the 338 ESBL-PE carriers, 372 isolates were recovered, mainly Escherichia coli (61.2%). Among 379 children, 1.1% carried a CP-GNB/VRE strain, and 12.4% carried an ESBL strain. Previous hospitalization outside mainland France, previous antimicrobial treatment and previous ESBL-PE carriage were the main risk factors associated with CP-GNB and/or VRE carriage.Conclusions: The low CP-GNB and VRE prevalence likely reflects the French policy to limit intrahospital spread of CP-GNB and VRE strains. [ABSTRACT FROM AUTHOR]

Aim: The emergence of vancomycin‐resistant Staphylococcus aureus (VRSA) has been identified as one of the most challenging problems in healthcare settings worldwide. Specific conjugation inhibitors' development is critical in the fight against the spread of emerging VRSA. The impact of Nigella sativa oil on VR genes conjugal transfer from Enterococcus faecium (VREtfm) to vancomycin‐sensitive S. aureus (VSSA) was investigated in this study. Methods and Results: Enterococciwere isolated from retail broilers, fish, cows' milk, and human urine. VR E. faecalis and VREtfm VanA phenotypes were prevalent in retail broiler samples. The VREtfm isolates were dominant, exhibiting high levels of resistance to gentamycin and ciprofloxacin antibiotics, as well as the existence of both vanA and vanB genes and virulence traits (ESP+, asa1+) as determined by PCR. Transconjugant VREtfm strains containing vanA/vabB and 20 kb plasmids (transfer frequency around 103) and carrying the Tn1546 transposon were identified. Tn1546 transposon transfer with its VR markers to VSSA was effectively inhibited in treated VREtfm donor strains with a sub‐minimum inhibitory concentration of N. sativa oil. The Significance and Impact of the Study: This work offers new insights for overcoming VR conjugal transfer utilizing natural N. sativa oil, as well as a suggestion for a novel specialized conjugation inhibitor that could effectively facilitate the difficulty of eliminating VR bacteria from healthcare settings. [ABSTRACT FROM AUTHOR]

Background Our objective was to determine if the addition of ultraviolet-C (UV-C) light to daily and discharge patient room cleaning reduces healthcare-associated infection rates of vancomycin-resistant enterococci (VRE) and Clostridioides difficile in immunocompromised adults. Methods We performed a cluster randomized crossover control trial in 4 cancer and 1 solid organ transplant in-patient units at the Johns Hopkins Hospital, Baltimore, Maryland. For study year 1, each unit was randomized to intervention of UV-C light plus standard environmental cleaning or control of standard environmental cleaning, followed by a 5-week washout period. In study year 2, units switched assignments. The outcomes were healthcare-associated rates of VRE or C. difficile. Statistical inference used a two-stage approach recommended for cluster-randomized trials with <15 clusters/arm. Results In total, 302 new VRE infections were observed during 45787 at risk patient-days. The incidence in control and intervention groups was 6.68 and 6.52 per 1000 patient-days respectively; the unadjusted incidence rate ratio (IRR) was 0.98 (95% confidence interval [CI],.78 − 1.22; P  = .54). There were 84 new C. difficile infections observed during 26118 at risk patient-days. The incidence in control and intervention periods was 2.64 and 3.78 per 1000 patient-days respectively; the unadjusted IRR was 1.43 (95% CI,.93 − 2.21; P  = .98). Conclusions When used daily and at post discharge in addition to standard environmental cleaning, UV-C disinfection did not reduce VRE or C. difficile infection rates in cancer and solid organ transplant units. [ABSTRACT FROM AUTHOR]

Aims: Childcare facilities act as microenvironments that facilitate and promote the selection, spread and transmission of antibiotic‐resistant micro‐organisms in the community. We focused on the study of antimicrobial resistance and genetic predispositions for β‐lactamase production in bacterial isolates from nursery teachers' clothing. Methods and Results: Antimicrobial resistance of bacterial strains belonging to Enterobacteriaceae, Enterococcus, Staphylococcus spp., Pseudomonas spp. and Bacillus spp. isolated from 80 samples of nursery teachers' clothing was determined. The selected ESβL genes were found in 30 (44.1%) of 68 strains examined. The CTX‐M type ESβL determinants were detected in 15.4%, 71.5% and 42.5% of the Enterobacteriaceae, Pseudomonas and Bacillus isolates, respectively. The OXA‐type coding genes were detected only in strains of the genera Pseudomonas (57.1%) and Bacillus (48.6%). Thus, most B. cereus strains were sensitive to the recommended antibiotics used to treat infections caused by these bacteria. Methicillin resistance was phenotypically confirmed in 27 (14.6%) of 185 staphylococcal isolates. Four isolates (2.2%) were identified as MRSA. Vancomycin resistance was not observed in any of the staphylococcal and enterococci strains. Conclusions: This study has shown that potential pathogens have been isolated from the clothing of nursery teachers, posing a risk of transmission to children. These clothes should be maintained and properly laundered to avoid cross‐contamination and the spread of multidrug‐resistant (MDR) bacteria in childcare centres. Significance and impact of the study: This study provides insight into the route of transmission of MDR micro‐organisms through the clothing of nursery teachers, to which greater importance should be given in the future. Proper procedures for the cleaning and use of clothing in daycare centres should be clarified and standardized. [ABSTRACT FROM AUTHOR]

Background The profound changes wrought by coronavirus disease 2019 (COVID-19) on routine hospital operations may have influenced performance on hospital measures, including healthcare-associated infections (HAIs). We aimed to evaluate the association between COVID-19 surges and HAI and cluster rates. Methods In 148 HCA Healthcare-affiliated hospitals, from 1 March 2020 to 30 September 2020, and a subset of hospitals with microbiology and cluster data through 31 December 2020, we evaluated the association between COVID-19 surges and HAIs, hospital-onset pathogens, and cluster rates using negative binomial mixed models. To account for local variation in COVID-19 pandemic surge timing, we included the number of discharges with a laboratory-confirmed COVID-19 diagnosis per staffed bed per month. Results Central line-associated blood stream infections (CLABSI), catheter-associated urinary tract infections (CAUTI), and methicillin-resistant Staphylococcus aureus (MRSA) bacteremia increased as COVID-19 burden increased. There were 60% (95% confidence interval [CI]: 23–108%) more CLABSI, 43% (95% CI: 8–90%) more CAUTI, and 44% (95% CI: 10–88%) more cases of MRSA bacteremia than expected over 7 months based on predicted HAIs had there not been COVID-19 cases. Clostridioides difficile infection was not significantly associated with COVID-19 burden. Microbiology data from 81 of the hospitals corroborated the findings. Notably, rates of hospital-onset bloodstream infections and multidrug resistant organisms, including MRSA, vancomycin-resistant enterococcus, and Gram-negative organisms, were each significantly associated with COVID-19 surges. Finally, clusters of hospital-onset pathogens increased as the COVID-19 burden increased. Conclusions COVID-19 surges adversely impact HAI rates and clusters of infections within hospitals, emphasizing the need for balancing COVID-related demands with routine hospital infection prevention. [ABSTRACT FROM AUTHOR]

Objectives: Synergistic combinations of daptomycin and β-lactam antibiotics are currently recommended for treatment of VRE bloodstream infection (BSI). The efficacy of these combinations is jeopardized by VRE inherently resistant to β-lactam antibiotics. The combination of daptomycin and fosfomycin is recommended as an alternative therapy for VRE BSI; however, clinical data to support use of this combination are lacking.Patients and Methods: We conducted a prospective observational multicentre study of patients treated with a combination of daptomycin and fosfomycin for VRE BSI during 2016-20. The primary outcome was 28 day mortality. Multivariable logistic regression was performed for outcome analysis.Results: The study included 106 patients from 1112 VRE BSI episodes. The overall 28 day mortality was 40.6%. The median (IQR) daptomycin dose was 10.18 mg/kg (9.43-10.70). The fosfomycin dose was 16 g/day (8-22.5). Ninety-six isolates were available for MIC testing. The fosfomycin MIC was 32 mg/L in 6 (6.3%), 64 mg/L in 68 (70.8%) and ≥128 mg/L in 22 (22.9%) isolates. Independent of Charlson comorbidity index and Pitt bacteraemia score, fosfomycin MIC ≥128 mg/L [adjusted OR (aOR) = 3.05; 95% CI = 1.01-9.19; P = 0.047] and daptomycin dose (aOR = 0.64; 95% CI = 0.43-0.97; P = 0.04) predicted mortality.Conclusions: Higher daptomycin dose and susceptibility to fosfomycin were independently associated with lower mortality in patients with VRE BSI. Our results suggest that higher doses of daptomycin are indicated for VRE BSI, whether or not it is used in combination with fosfomycin. The combination was less effective for patients with fosfomycin-resistant isolates. [ABSTRACT FROM AUTHOR]

Aims: Worldwide, studies regarding antimicrobial resistance in rabbits are scarce. In addition, it seems that rearing conditions have important impact on emergence and spread of antimicrobial‐resistant bacteria. Thus, the authors sought to (1) assess the role of rabbits residing across diverse ecosystems as potential reservoirs of antimicrobial‐resistant enterococci and (2) investigate the genetic background of detected resistances. Methods and Results: Faecal samples from 60 healthy farmed rabbits (one farm), 35 laboratory rabbits and 31 wild rabbits were analysed. Overall, 97 enterococci isolates were accumulated, as follows: 44 E. faecium, 37 E. faecalis, 7 E. gallinarum, 5 E. durans and 4 E. avium. E. faecalis isolates were statistically associated with farm rabbits and wild rabbits (p < 0.05). High rates of resistance were observed for tetracycline (60.8%; tetM [n = 48; 81.3%], tetO [n = 7; 11.8%] and tetL [n = 1; 1.7%]), erythromycin (43.3%; msr(A) [n = 14; 33.3%] and ermB [n = 13; 31%]), ampicillin (29.9%), streptomycin (26.8%; ant(6)‐Ia [n = 3, 11.5%]) and vancomycin (21.6%; vanA [one E. faecium + one E. faecalis; 9.5%]). Low frequencies of resistance were observed for teicoplanin (9.2%), linezolid (8.2%), ciprofloxacin (7.2%) and gentamicin (1%; aac(6′)‐Ie‐aph(2″)‐Ia). Resistance to ampicillin and vancomycin was associated with laboratory rabbits (p < 0.05). Int‐Tn (Tn916/1545) was detected in 27 (27.8%) isolates, of which 10 isolates co‐harboured tetM and ermB genes, while 16 comprised tetM. Conclusion: Findings indicate that clinically relevant enterococci species isolated from rabbits are frequently resistant to antimicrobials and harbour a range of genes associated with the Tn916/1545 family. Significance and Impact of the study: This study highlights the high rates of antimicrobial‐resistant enterococci from rabbits and the occurrence of both vancomycin‐ and linezolid‐resistant isolates, potentially representing a very serious threat to human and animal health. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the genetic elements and the transferability of linezolid resistance genes in three enterococci co-carrying cfr(D) and poxtA2 isolates from manure of a swine farm in central Italy.Methods: Two Enterococcus faecalis isolates and one Enterococcus casseliflavus isolate carrying both cfr(D) and poxtA genes were tested for their susceptibility to florfenicol, chloramphenicol, linezolid, tedizolid, tetracycline and vancomycin. Linezolid resistance genes transfer (filter mating), localization (S1-PFGE/hybridization), genetic elements and relatedness between isolates (WGS) were analysed.Results: Two E. faecalis isolates and one E. casseliflavus isolate carried the cfr(D) gene and the recently described poxtA2 variant. In the three enterococci, cfr(D) and poxtA2 were co-located on a 33 480 bp plasmid, pV386, 95%-100% identical (coverage 84%) to the Tn6349 transposon of Staphylococcus aureus AOUC-0915. In all isolates, both genes also showed a chromosomal location. Same sequence identities were found from the comparison with currently known poxtA2 genetic elements. In the plasmid pV386, poxtA2 gene was not bounded by two IS1216, as described in pIB-BOL, but closely associated to the cfr(D) and fexA genes. pV386 was always transferred by filter mating to Enterococcus faecium 64/3 recipient.Conclusions: The occurrence of the pV386 plasmid in E. faecalis and E. casseliflavus from swine manure is of great concern and highlights the need for control measures to contain its spread to other enterococcal species. [ABSTRACT FROM AUTHOR]

Background: Vancomycin-resistant Enterococcus faecium (VREfm) cause a wide range of hospital infections. Ireland has had one of the highest invasive VREfm infection rates in Europe over the last decade, yet little is known about Irish VREfm.Objectives: To investigate the population structure of Irish VREfm, explore diversity by analysing the vanA transposon region and compare Irish, Danish and global isolates.Methods: E. faecium (n = 648) from five Irish hospitals were investigated, including VREfm [547 rectal screening and 53 bloodstream infection (BSI)] isolates and 48 vancomycin-susceptible (VSEfm) BSI isolates recovered between June 2017 and December 2019. WGS and core-genome MLST (cgMLST) were used to assess population structure. Genetic environments surrounding vanA were resolved by hybrid assembly of short-read (Illumina) and long-read (Oxford Nanopore Technologies) sequences.Results: All isolates belonged to hospital-adapted clade A1 and the majority (435/648) belonged to MLST ST80. The population structure was highly polyclonal; cgMLST segregated 603/648 isolates into 51 clusters containing mixtures of screening and BSI isolates, isolates from different hospitals, and VREfm and VSEfm. Isolates within clusters were closely related (mean average ≤16 allelic differences). The majority (96.5%) of VREfm harboured highly similar vanA regions located on circular or linear plasmids with multiple IS1216E insertions, variable organization of vanA operon genes and 78.6% harboured a truncated tnpA transposase. Comparison of 648 Irish isolates with 846 global E. faecium from 30 countries using cgMLST revealed little overlap.Conclusions: Irish VREfm are polyclonal, yet harbour a characteristic plasmid-located vanA region with multiple IS1216E insertions that may facilitate spread. [ABSTRACT FROM AUTHOR]

Daptomycin is a cyclic lipopeptide used in the treatment of vancomycin-resistant Enterococcus faecium (VREfm). However, the development of daptomycin-resistant VREfm challenges the treatment of nosocomial VREfm infections. Resistance mechanisms of daptomycin are not fully understood. Here, we analyzed the genomic changes leading to a daptomycin-susceptible VREfm isolate becoming resistant after 50 days of daptomycin and linezolid combination therapy. A total of seven isogenic VREfm isolates from the same patient (daptomycin-susceptible and daptomycin-resistant) were analyzed using Illumina whole genome sequencing, and two isolates were further characterized with Nanopore sequencing. One nonsynonymous SNP in the rpoC gene previously shown to harbor mutations in daptomycin-resistant VREfm was identified in the daptomycin-resistant isolates. Whole genome comparative analysis identified the loss of a 46.5 kb fragment, duplication of a 29.7 kb fragment, and integration of two plasmids upon acquisition of daptomycin resistance. Transmission electron microscopy showed similar alterations in cell morphology and cell wall structure as have previously been described in daptomycin-resistant E. faecalis. [ABSTRACT FROM AUTHOR]

Background: A marked genotype shift among vancomycin-resistant Enterococcus faecium (VREfm) from vanB to vanA in Australia between 2011 and 2015 is a well-known phenomenon. It is hypothesized that this was caused by multiple independent clones emerging simultaneously in different settings and/or regions.Objectives: To gain insights into the circumstances surrounding the shift from vanB to vanA VREfm in one Australian hospital.Methods: The genomes of 69 vanA VREfm isolates from St George Hospital collected between 2009 and 2018 were studied. An expansion of ST80 vanA VREfm was noted following a single introduction. ST80 isolates were thus further characterized using hybrid sequencing and contextualized through comparisons with other published Australian ST80 isolates. Phylogenies were constructed with plasmid sequences compared with the index isolate.Results: The 2011 expansion of ST80 vanA VREfm isolates in our institution originated from the 2009 index isolate, from a patient transferred from overseas. Phylogenetic analysis with other Australian ST80 vanA VREfm isolates showed that the 2011 expansion event was unique, with limited spread to adjacent local health districts. Plasmid analysis showed multiple variants, which can also be traced back to the 2009 isolate, consistent with ongoing plasmid adaptation over time.Conclusions: These findings confirm an expansion event following a VREfm introduction event leading to a sustained clonal and plasmid outbreak over several years. Moreover, it demonstrates the complexity of countrywide replacement events. This study also highlights the use of hybrid sequencing in establishing an epidemiological relationship to the index isolate that was initially inapparent. [ABSTRACT FROM AUTHOR]

Background Clostridioides difficile infection (CDI) is a leading cause of hospital-associated antibiotic-related diarrhea and deaths worldwide. Vancomycin is one of the few antibiotics recommended for both nonsevere and severe CDI cases. We sought to determine whether vancomycin nonsusceptible C. difficile strains are circulating in the patient population. Methods Stool samples from patients with CDI were collected from 438 and 98 patients at a large university hospital in Houston, Texas, and Nairobi, Kenya, respectively. The stools were examined for the presence of vancomycin and metronidazole nonsusceptible C. difficile using broth dilution culture, Etest (BioMérieux, France), polymerase chain reaction (PCR), whole-genome sequencing, and in vivo testing in a CDI mouse model. Results Of the Houston stool samples, 114/438 (26%) had vancomycin nonsusceptible C. difficile isolates and 128/438 (29%) were metronidazole nonsusceptible. Similarly, 66 out of 98 (67%) and 83/98 (85%) of the Nairobi patients harbored vancomycin and metronidazole nonsusceptible isolates, respectively. Vancomycin treatment of a CDI mouse model infected with a vancomycin nonsusceptible isolate failed to eradicate the infection. Whole-genome sequencing analyses did not identify vanA genes, suggesting a different mechanism of resistance. Conclusions C. difficile strains exhibiting reduced susceptibility to vancomycin are currently circulating in patient populations. The spread of strains resistance to vancomycin, a first-line antibiotic for CDI, poses a serious therapeutic challenge. Routine susceptibility testing may be necessary. [ABSTRACT FROM AUTHOR]

Background Vancomycin-resistant enterococci (VRE) are a major cause of morbidity and mortality in immunocompromised patients. Tracking the dissemination of VRE strains is crucial to understand the dynamics of emergence and spread of VRE in the hospital setting. Methods Whole genome sequencing (WGS) and phylogenetic analyses were performed to identify dominant VRE strains and potential transmission networks between 35 patients with VRE-positive rectal swabs and their rooms (main rooms and bathrooms) on the leukemia (LKM) and the hematopoietic cell transplant (HCT) floors. Sequence types (STs), drug resistance genes, and patients' outcomes were also determined. Results A total of 89 VRE strains grouped into 10 different STs, of which newly described STs were isolated from both floors (ST736, ST494, ST772, and ST1516). We observed highly genetically related strains transmitted between rooms, floors, and time periods in an average period of 39 days (ranging from 3 to 90 days). Of 5 VRE bacteremia events, 3 strains were lacking the pili operon fms14–17–13 (ST203) and the remaining 2 were resistant to daptomycin (DAP; ST736, ST664). Of 10 patients harboring DAP-resistant strains, only 2 were exposed to DAP within 4 months before strain recovery. Conclusions Our comparisons of VRE strains derived from the environment and immunocompromised patients confirmed horizontal transfer of highly related genetic lineages of multidrug-resistant (particularly to DAP) VRE strains between HCT and LKM patients and their room environment. Implementing WGS can be useful in distinguishing VRE reservoirs where interventions can be targeted to prevent and control the spread of highly resistant organisms. [ABSTRACT FROM AUTHOR]

Background Antibiotic stewardship programs (ASPs) have demonstrated success at reducing costs, yet there is limited quality evidence of their effectiveness in reducing infections of high-profile drug-resistant organisms. Methods This retrospective, cohort study included all Kaiser Permanente Southern California (KPSC) members aged ≥18 years hospitalized in 9 KPSC hospitals from 1 January 2008 to 31 December 2016. We measured the impact of staggered ASP implementation on consumption of 18 ASP-targeted antibiotics using generalized linear mixed-effects models. We used multivariable generalized linear mixed-effects models to estimate the adjusted effect of an ASP on rates of infection with drug-resistant organisms. Analyses were adjusted for confounding by time, cluster effects, and patient- and hospital-level characteristics. Results We included 765 111 hospitalizations (288 257 pre-ASP, 476 854 post-ASP). By defined daily dose, we found a 6.1% (−7.5% to −4.7%) overall decrease antibiotic use post-ASP; by days of therapy, we detected a 4.3% (−5.4% to −3.1%) decrease in overall use of antibiotics. The number of prescriptions increased post-ASP (1.04 [1.03–1.05]). In adjusted analyses, we detected an overall increase in vancomycin-resistant enterococci infections post-ASP (1.37 [1.10–1.69]). We did not detect a change in the rates of extended-spectrum beta-lactamase, carbapenem-resistant Enterobacteriaceae, and multidrug-resistant Pseudomonas aeruginosa infections post-ASP. Conclusions ASPs with successful reductions in consumption of targeted antibiotics may not see changes in infection rates with antibiotic-resistant organisms in the 2 to 6 years post-implementation. There are likely differing timescales for reversion to susceptibility across organisms and antibiotics, and unintended consequences from compensatory prescribing may occur. [ABSTRACT FROM AUTHOR]

Background: Antibiotic tolerance allows bacteria to overcome antibiotic treatment transiently and potentially accelerates the emergence of resistance. However, our understanding of antibiotic tolerance at the genetic level during adaptive evolution of Staphylococcus aureus remains incomplete. We sought to identify the mutated genes and verify the role of these genes in the formation of vancomycin tolerance in S. aureus.Methods: Vancomycin-susceptible S. aureus strain Newman was used to induce vancomycin-tolerant isolates in vitro by cyclic exposure under a high concentration of vancomycin (20× MIC). WGS and Sanger sequencing were performed to identify the genetic mutations. The function of mutated genes in vancomycin-tolerant isolates were verified by gene complementation. Other phenotypes of vancomycin-tolerant isolates were also determined, including mutation frequency, autolysis, lysostaphin susceptibility, cell wall thickness and cross-tolerance.Results: A series of vancomycin-tolerant S. aureus (VTSA) strains were isolated and 18 mutated genes were identified by WGS. Among these genes, pbp4, htrA, stp1, pth and NWMN_1068 were confirmed to play roles in VTSA formation. Mutation of mutL promoted the emergence of VTSA. All VTSA showed no changes in growth phenotype. Instead, they exhibited reduced autolysis, decreased lysostaphin susceptibility and thickened cell walls. In addition, all VTSA strains were cross-tolerant to antibiotics targeting cell wall synthesis but not to quinolones and lipopeptides.Conclusions: Our results demonstrate that genetic mutations are responsible for emergence of phenotypic tolerance and formation of vancomycin tolerance may lie in cell wall changes in S. aureus. [ABSTRACT FROM AUTHOR]

Background: Vancomycin resistance is mostly associated with Enterococcus faecium due to Tn1546-vanA located on narrow- and broad-host plasmids of various families. This study's aim was to analyse the effects of acquiring Tn1546-carrying plasmids with proven epidemicity in different bacterial host backgrounds.Methods: Widespread Tn1546-carrying plasmids of different families RepA_N (n = 5), Inc18 (n = 4) and/or pHTβ (n = 1), and prototype plasmids RepA_N (pRUM) and Inc18 (pRE25, pIP501) were analysed. Plasmid transferability and fitness cost were assessed using E. faecium (GE1, 64/3) and Enterococcus faecalis (JH2-2/FA202/UV202) recipient strains. Growth curves (Bioscreen C) and Relative Growth Rates were obtained in the presence/absence of vancomycin. Plasmid stability was analysed (300 generations). WGS (Illumina-MiSeq) of non-evolved and evolved strains (GE1/64/3 transconjugants, n = 49) was performed. SNP calling (Breseq software) of non-evolved strains was used for comparison.Results: All plasmids were successfully transferred to different E. faecium clonal backgrounds. Most Tn1546-carrying plasmids and Inc18 and RepA_N prototypes reduced host fitness (-2% to 18%) while the cost of Tn1546 expression varied according to the Tn1546-variant and the recipient strain (9%-49%). Stability of Tn1546-carrying plasmids was documented in all cases, often with loss of phenotypic resistance and/or partial plasmid deletions. SNPs and/or indels associated with essential bacterial functions were observed on the chromosome of evolved strains, some of them linked to increased fitness.Conclusions: The stability of E. faecium Tn1546-carrying plasmids in the absence of selective pressure and the high intra-species conjugation rates might explain the persistence of vancomycin resistance in E. faecium populations despite the significant burden they might impose on bacterial host strains. [ABSTRACT FROM AUTHOR]

Objectives: The increasing prevalence of VRE necessitates their reliable detection, especially for low-level resistance mediated by vanB in Enterococcus faecium. In this prospective study we analysed if vanB-mediated vancomycin resistance can be reliably detected by Vitek2.Methods: One thousand, three hundred and forty-four enterococcal isolates from routine clinical specimens were tested by Vitek2 (bioMérieux, Nürtingen, Germany). Additionally, a bacterial suspension (with a turbidity equivalent to that of a 0.5 McFarland standard) was inoculated on chromID VRE screening agar (bioMérieux) and incubated for 48 h. If vancomycin tested susceptible by Vitek2 but growth was detected on the screening agar, PCR for vanA/vanB was performed (GeneXpert vanA/B test, Cepheid, Frankfurt, Germany). For isolates that tested susceptible to vancomycin by Vitek2 but were vanA/B positive, MICs were determined before and after cultivation in broth with increasing concentrations of vancomycin.Results: One hundred and fifty-six out of 491 E. faecium were VRE and were predominantly vanB positive (81.0%). Of these, Vitek2 did not identify 14 as VRE (sensitivity 91.0%). By broth microdilution 9/14 isolates demonstrated high MICs (≥32 mg/L) and 5/14 showed low vancomycin MICs, which did not increase despite vancomycin exposure. Three of the 14 isolates demonstrated growth on chromID VRE; after vancomycin exposure seven additional isolates were able to grow on chromID VRE.Conclusions: Vitek2 fails to detect vanB-mediated vancomycin resistance consistently, especially, but not limited to, low-level resistance. As this may lead to treatment failure and further dissemination of vanB VRE, additional methods (e.g. culture on VRE screening agar or PCR) are necessary to reliably identify vanB-positive enterococci in clinical routine. [ABSTRACT FROM AUTHOR]

Background The Benefits of Universal Glove and Gown (BUGG) cluster randomized trial found varying effects on methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus and no increase in adverse events. The aim of this study was to assess whether the intervention decreases the acquisition of antibiotic-resistant gram-negative bacteria. Methods This was a secondary analysis of a randomized trial in 20 hospital intensive care units. The intervention consisted of healthcare workers wearing gloves and gowns when entering any patient room compared to standard care. The primary composite outcome was acquisition of any antibiotic-resistant gram-negative bacteria based on surveillance cultures. Results A total of 40 492 admission and discharge perianal swabs from 20 246 individual patient admissions were included in the primary outcome. For the primary outcome of acquisition of any antibiotic-resistant gram-negative bacteria, the intervention had a rate ratio (RR) of 0.90 (95% confidence interval [CI],.71–1.12; P  = .34). Effects on the secondary outcomes of individual bacteria acquisition were as follows: carbapenem-resistant Enterobacteriaceae (RR, 0.86 [95% CI,.60–1.24; P  = .43), carbapenem-resistant Acinetobacter (RR, 0.81 [95% CI,.52–1.27; P  = .36), carbapenem-resistant Pseudomonas (RR, 0.88 [95% CI,.55–1.42]; P  = .62), and extended-spectrum β-lactamase–producing bacteria (RR, 0.94 [95% CI,.71–1.24]; P  = .67). Conclusions Universal glove and gown use in the intensive care unit was associated with a non–statistically significant decrease in acquisition of antibiotic-resistant gram-negative bacteria. Individual hospitals should consider the intervention based on the importance of these organisms at their hospital, effect sizes, CIs, and cost of instituting the intervention. Clinical Trials Registration NCT01318213. [ABSTRACT FROM AUTHOR]

Background In October 2007, Veterans Affairs (VA) launched a nationwide effort to reduce methicillin-resistant Staphylococcus aureus (MRSA) transmission called the National MRSA Prevention Initiative. Although the initiative focused on MRSA, recent evidence suggests that it also led to a significant decrease in hospital-onset (HO) gram-negative rod (GNR) bacteremia, vancomycin-resistant Enterococci (VRE), and Clostridioides difficile infections. The objective of this analysis was to evaluate the cost-effectiveness and the budget impact of the initiative taking into account MRSA, GNR, VRE, and C. difficile infections. Methods We developed an economic model using published data on the rate of MRSA hospital-acquired infections (HAIs) and HO-GNR bacteremia in the VA from October 2007 to September 2015, estimates of the attributable cost and mortality of these infections, and the costs associated with the intervention obtained through a microcosting approach. We explored several different assumptions for the rate of infections that would have occurred if the initiative had not been implemented. Effectiveness was measured in life-years (LYs) gained. Results We found that during fiscal years 2008–2015, the initiative resulted in an estimated 4761–9236 fewer MRSA HAIs, 1447–2159 fewer HO-GNR bacteremia, 3083–3602 fewer C. difficile infections, and 2075–5393 fewer VRE infections. The initiative itself was estimated to cost $561 million over this 8-year period, whereas the cost savings from prevented MRSA HAIs ranged from $165 to $315 million and from prevented HO-GNR bacteremia, CRE and C. difficile infections ranged from $174 to $200 million. The incremental cost-effectiveness of the initiative ranged from $12 146 to $38 673/LY when just including MRSA HAIs and from $1354 to $4369/LY when including the additional pathogens. The overall impact on the VA's budget ranged from $67 to$195 million. Conclusions An MRSA surveillance and prevention strategy in VA may have prevented a substantial number of infections from MRSA and other organisms. The net increase in cost from implementing this strategy was quite small when considering infections from all types of organisms. Including spillover effects of organism-specific prevention efforts onto other organisms can provide a more comprehensive evaluation of the costs and benefits of these interventions. [ABSTRACT FROM AUTHOR]

Background Environmental contamination is an important source of hospital multidrug-resistant organism (MDRO) transmission. Factors such as patient MDRO contact precautions (CP) status, patient proximity to surfaces, and unit type likely influence MDRO contamination and bacterial bioburden levels on patient room surfaces. Identifying factors associated with environmental contamination in patient rooms and on shared unit surfaces could help identify important environmental MDRO transmission routes. Methods Surfaces were sampled from MDRO CP and non-CP rooms, nursing stations, and mobile equipment in acute care, intensive care, and transplant units within 6 acute care hospitals using a convenience sampling approach blinded to cleaning events. Precaution rooms had patients with clinical or surveillance tests positive for methicillin-resistant Staphylococcus aureus , vancomycin-resistant enterococci, carbapenem-resistant Enterobacteriaceae or Acinetobacter within the previous 6 months, or Clostridioides difficile toxin within the past 30 days. Rooms not meeting this definition were considered non-CP rooms. Samples were cultured for the above MDROs and total bioburden. Results Overall, an estimated 13% of rooms were contaminated with at least 1 MDRO. MDROs were detected more frequently in CP rooms (32% of 209 room-sample events) than non-CP rooms (12% of 234 room-sample events). Surface bioburden did not differ significantly between CP and non-CP rooms or MDRO-positive and MDRO-negative rooms. Conclusions CP room surfaces are contaminated more frequently than non-CP room surfaces; however, contamination of non-CP room surfaces is not uncommon and may be an important reservoir for ongoing MDRO transmission. MDRO contamination of non-CP rooms may indicate asymptomatic patient MDRO carriage, inadequate terminal cleaning, or cross-contamination of room surfaces via healthcare personnel hands. [ABSTRACT FROM AUTHOR]

Background Contact precautions for endemic methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are under increasing scrutiny, in part due to limited clinical trial evidence. Methods We retrospectively analyzed data from the Strategies to Reduce Transmission of Antimicrobial Resistant Bacteria in Intensive Care Units (STAR*ICU) trial to model the use of contact precautions in individual intensive care units (ICUs). Data included admission and discharge times and surveillance test results. We used a transmission model to estimate key epidemiological parameters, including the effect of contact precautions on transmission. Finally, we performed multivariate meta-regression to identify ICU-level factors associated with contact precaution effects. Results We found that 21% of admissions (n = 2194) were placed on contact precautions, with most for MRSA and VRE. We found little evidence that contact precautions reduced MRSA transmission. The estimated change in transmission attributed to contact precautions was –16% (95% credible interval, –38% to 15%). VRE transmission was higher than MRSA transmission due to contact precautions, but not significantly. In our meta-regression, we did not identify associations between ICU-level factors and estimated contact precaution effects. Importation and transmission were higher for VRE than for MRSA, but clearance rates were lower for VRE than for MRSA. Conclusions We found little evidence that contact precautions implemented during the STAR*ICU trial reduced transmission of MRSA or VRE. We did find important differences in the transmission dynamics between MRSA and VRE. Differences in organism and healthcare setting may impact the efficacy of contact precautions. [ABSTRACT FROM AUTHOR]

Introduction: Vancomycin-resistant enterococci (VRE) are classified by the Centers for Diseases Control and Prevention as a serious antibiotic resistance threat. Our study aims to characterize the epidemiology, associated conditions, and outcomes of VRE infections among hospitalized patients in the U.S. military health system (MHS).Materials and Methods: We performed a retrospective cohort study of patients with VRE infection using the MHS database. Cases included all patients admitted to a military treatment facility for ≥2 days from October 2008 to September 2015 with a clinical culture growing Enterococcus faecalis, Enterococcus faecium, or Enterococcus species (unspecified), reported as resistant to vancomycin. Co-morbid conditions and procedures associated with VRE infection were identified by multivariable conditional logistic regression. Patient case-mix adjusted outcomes including in-hospital mortality, length of stay, and hospitalization cost were evaluated by high-dimensional propensity score adjustment.Results: During the seven-year study period and among 1,161,335 hospitalized patients within the MHS, we identified 577 (0.05%) patients with VRE infection. A majority of VRE infections were urinary tract infections (57.7%), followed by bloodstream (24.7%), other site/device-related (12.9%), respiratory (2.9%), and wound infections (1.8%). Risk factors for VRE infection included invasive gastrointestinal, pulmonary, and urologic procedures, indwelling devices, and exposure to 4th generation cephalosporins, but not to glycopeptides. Patients hospitalized with VRE infection had significantly higher hospitalization costs (attributable difference [AD] $135,534, P<0.001), prolonged hospital stays (AD 20.44 days, P<0.001, and higher in-hospital mortality (case-mix adjusted odds ratio 5.77; 95% confidence interval 4.59-7.25).Conclusions: VRE infections carry a considerable burden for hospitalized patients given their impact on length of stay, hospitalization costs, and in-hospital mortality. Active surveillance and infection control efforts should target those identified as high-risk for VRE infection. Antimicrobial stewardship programs should focus on limiting exposure to 4th generation cephalosporins. [ABSTRACT FROM AUTHOR]

Objectives: To determine the epidemiological cut-off values (ECOFFs) of norvancomycin for Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus hominis.Methods: We collected 1199 clinical isolates of Staphylococcus species from five laboratories located in four cities in China. MICs and inhibitory zone diameters of norvancomycin were determined by broth microdilution and the disc diffusion method, separately. ECOFFs of norvancomycin for four species were calculated by ECOFFinder software following EUCAST principles. Methicillin and vancomycin resistance genes (mecA/mecC and vanA/vanB/vanC/vanD/vanE) were screened for by PCR in all isolates. Pearson correlation and χ2 test were used to calculate the correlation of MICs and inhibition zone diameters, and MICs and resistance genes, respectively.Results: MICs of norvancomycin for all strains from five laboratories fell in the range of 0.12-2 mg/L. ECOFFs of norvancomycin were determined to be 2 mg/L for S. epidermidis and S. haemolyticus and 1 mg/L for S. aureus and S. hominis. A weak correlation was observed between MIC values and zone diameters for S. haemolyticus (r = -0.36) and S. hominis (r = -0.26), while no correlation was found for S. epidermidis and S. aureus. The mecA gene was detected in 63.1% of Staphylococcus, whereas no isolate carried mecC, vanA, vanB, vanC, vanD or vanE. ECOFFs of norvancomycin were not correlated with mecA gene carriage in Staphylococcus species.Conclusions: ECOFFs of norvancomycin for four Staphylococcus species were determined, which will be helpful to differentiate WT strains. The correlation of MICs and zone diameters of norvancomycin was weak in Staphylococcus species. [ABSTRACT FROM AUTHOR]

Background: VRE are nosocomial pathogens with an increasing incidence in recent decades. Rapid detection is crucial to reduce their spread and prevent infections and outbreaks.Objectives: To evaluate a lateral flow immunoassay (LFIA) (called NG-Test VanA) for the rapid and reliable detection of VanA-producing VRE (VanA-VRE) from colonies and broth.Methods: NG-Test VanA was validated on 135 well-characterized enterococcal isolates grown on Mueller-Hinton (MH) agar (including 40 VanA-VRE). Different agar plates and culture broths widely used in routine laboratories for culture of enterococci were tested.Results: All 40 VanA-VRE clinical isolates were correctly detected in less than 15 min irrespective of the species expressing the VanA ligase and the medium used for bacterial growth. No cross-reaction was observed with any other clinically relevant ligases (VanB, C1, C2, D, E, G, L, M and N). Overall, the sensitivity and specificity of the assay were 100% for VanA-VRE grown on MH agar plates. NG-Test VanA accurately detects VanA-VRE irrespective of the culture medium (agar and broth). Band intensity was increased when using bacteria grown on vancomycin-containing culture media or on MH close to the vancomycin disc as a consequence of VanA induction. The limit of detection of the assay was 6.3 × 106 cfu per test with bacteria grown on MH plates and 4.9 × 105 cfu per test with bacteria grown on ChromID® VRE plates.Conclusions: NG-Test VanA is efficient, rapid and easy to implement in the routine workflow of a clinical microbiology laboratory for the confirmation of VanA-VRE. [ABSTRACT FROM AUTHOR]

Background The evolving antibiotic-resistant behavior of health care–associated methicillin-resistant Staphylococcus aureus (HA-MRSA) USA100 strains are of major concern. They are resistant to a broad class of antibiotics such as macrolides, aminoglycosides, fluoroquinolones, and many more. Findings The selection of appropriate antibiotic susceptibility examination media is very important. Thus, we use bacteriological (cation-adjusted Mueller-Hinton broth) as well as physiological (R10LB) media to determine the effect of vancomycin on USA100 strains. The study includes the profiling behavior of HA-MRSA USA100 D592 and D712 strains in the presence of vancomycin through various high-throughput assays. The US100 D592 and D712 strains were characterized at sub-inhibitory concentrations through growth curves, RNA sequencing, bacterial cytological profiling, and exo-metabolomics high throughput experiments. Conclusions The study reveals the vancomycin resistance behavior of HA-MRSA USA100 strains in dual media conditions using wide-ranging experiments. [ABSTRACT FROM AUTHOR]

Background Patients entering nursing facilities (NFs) are frequently colonized with antibiotic-resistant organisms (AROs). To understand the determinants of ARO colonization on NF admission, we applied whole-genome sequencing to track the spread of 4 ARO species across regional NFs and evaluated patient-level characteristics and transfer acute care hospitals (ACHs) as risk factors for colonization. Methods Patients from 6 NFs (n = 584) were surveyed for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecalis/faecium (VREfc/VREfm), and ciprofloxacin-resistant Escherichia coli (CipREc) colonization. Genomic analysis was performed to quantify ARO spread between NFs and compared to patient-transfer networks. The association between admission colonization and patient-level variables and recent ACH exposures was examined. Results The majority of ARO isolates belonged to major healthcare-associated lineages: MRSA (sequence type [ST] 5); VREfc (ST6); CipREc (ST131), and VREfm (clade A). While the genomic similarity of strains between NF pairs was positively associated with overlap in their feeder ACHs (P <.05 for MRSA, VREfc, and CipREc), limited phylogenetic clustering by either ACH or NF supported regional endemicity. Significant predictors for ARO colonization on NF admission included lower functional status and recent exposure to glycopeptides (adjusted odds ratio [aOR], > 2 for MRSA and VREfc/VREfm) or third-/fourth-generation cephalosporins (aOR, > 2 for MRSA and VREfm). Transfer from specific ACHs was an independent risk factor for only 1 ARO/ACH pair (VREfm/ACH19: aOR, 2.48). Conclusions In this region, healthcare-associated ARO lineages are endemic among connected NFs and ACHs, making patient characteristics more informative of NF admission colonization risk than exposure to specific ACHs. [ABSTRACT FROM AUTHOR]

Background Bloodstream infections (BSIs) occur frequently after hematopoietic stem cell transplantation (HSCT). We examined the microbiology of BSI in pediatric HSCT recipients over a 2-decade period at our institution to inform empirical antimicrobial prescribing and infection prevention strategies. Methods We conducted a retrospective cohort study of children (<18 years) who underwent HSCT at Duke University between 1997 and 2015. We used recurrent-event gap-time Cox proportional hazards models to determine the hazards of all-cause and cause-specific BSI according to HSCT year. We compared the median time to BSI by causative organism type and evaluated for temporal trends in the prevalence of antibiotic resistance among causative organisms. Results A total of 865 BSI occurred in 1311 children, including 412 (48%) Gram-positive bacterial, 196 (23%) Gram-negative bacterial, 56 (6%) fungal, 23 (3%) mycobacterial, and 178 (21%) polymicrobial BSI. The hazard of all BSIs did not change substantially over time during the study period, but the hazard of fungal BSIs declined over time during the study period (P  = .04). Most fungal BSIs (82%) occurred in the first 100 days after HSCT, whereas mycobacterial BSIs occurred later after HSCT than BSIs caused by other organisms (P  < .0001). The prevalence of vancomycin resistance among BSIs caused by Enterococcus faecium increased during the study period (P  = .0007). The risk of 2-year mortality in children was increased with BSI (P  = .02), Gram-negative bacterial BSI (P  = .02), and fungal BSI (P  < .0001). Conclusions Despite expanded practices for BSI prevention over the past several decades, the incidence of BSI remains high in pediatric HSCT recipients at our institution. Additional strategies are urgently needed to effectively prevent BSIs in this high-risk population. [ABSTRACT FROM AUTHOR]

Objectives: To analyse the rectal carriage rate and the molecular epidemiology of vancomycin-resistant Enterococcus faecium (VREfm) recovered from patients upon hospital admission.Methods: Adult patients were screened at six German university hospitals from five different federal states upon hospital admission for rectal colonization with VREfm between 2014 and 2018. Molecular characterization of VREfm was performed by WGS followed by MLST and core-genome MLST analysis.Results: Of 16350 patients recruited, 263 were colonized with VREfm, with increasing prevalence rates during the 5 year study period (from 0.8% to 2.6%). In total, 78.5% of the VREfm were vanB positive and 20.2% vanA positive, while 1.2% harboured both vanA and vanB. The predominant ST was ST117 (56.7%) followed by ST80 (15%), ST203 (10.9%), ST78 (5.7%) and ST17 (3.2%). ST117/vanB VREfm isolates formed a large cluster of 96 closely related isolates extending across all six study centres and four smaller clusters comprising 13, 5, 4 and 3 isolates each. In contrast, among the other STs inter-regional clonal relatedness was rarely observed.Conclusions: To our knowledge, this is the largest admission prevalence and molecular epidemiology study of VREfm. These data provide insight into the epidemiology of VREfm at six German university hospitals and demonstrate the remarkable inter-regional clonal expansion of the ST117/vanB VREfm clone. [ABSTRACT FROM AUTHOR]

In Ontario, Canada, since 2012, some hospitals discontinued contact precautions for vancomycin-resistant Enterococcus (VRE). Between 2009 and 2018, there was an associated rise in VRE bloodstream infections in hospitals where contact precautions were discontinued but not in hospitals that maintained contact precautions. These data suggest contact precautions are important for hospital VRE control programs. [ABSTRACT FROM AUTHOR]

Background Limited data exists regarding the effects of empiric antibiotic use in pediatric oncology patients with febrile neutropenia (FN) on the development of antibiotic resistance. We evaluated the impact of a change in our empiric FN guideline limiting vancomycin exposure on the development of vancomycin-resistant Enterococcus in pediatric oncology patients. Methods Retrospective, quasi-experimental, single-center study using interrupted timeseries analysis in oncology patients aged ≤18 years with at least 1 admission for FN between 2009 and 2015. Risk strata incorporated diagnosis, chemotherapy phase, Down syndrome, septic shock, and typhlitis. Microbiologic data and inpatient antibiotic use were obtained by chart review. Segmented Poisson regression was used to compare VRE incidence and antibiotic days of therapy (DOT) before and after the intervention. Results We identified 285 patients with 697 FN episodes pre-intervention and 309 patients with 691 FN episodes postintervention. The proportion of high-risk episodes was similar in both periods (49% vs 48%). Empiric vancomycin DOT/1000 FN days decreased from 315 pre-intervention to 164 post-intervention (P <.01) in high-risk episodes and from 199 to 115 in standard risk episodes (P <.01). Incidence of VRE/1000 patient-days decreased significantly from 2.53 pre-intervention to 0.90 post-intervention (incidence rate ratio, 0.14; 95% confidence interval, 0.04–0.47; P =.002). Conclusions A FN guideline limiting empiric vancomycin exposure was associated with a decreased incidence of VRE among pediatric oncology patients. Antimicrobial stewardship interventions are feasible in immunocompromised patients and can impact antibiotic resistance. [ABSTRACT FROM AUTHOR]

Background Vancomycin is now a preferred treatment for all cases of Clostridioides difficile infection (CDI), regardless of disease severity. Concerns remain that a large-scale shift to oral vancomycin may increase selection pressure for vancomycin-resistant Enterococci (VRE). We evaluated the risk of VRE following oral vancomycin or metronidazole treatment among patients with CDI. Methods We conducted a retrospective cohort study of patients with CDI in the US Department of Veterans Affairs health system between 1 January 2006 and 31 December 2016. Patients were included if they were treated with metronidazole or oral vancomycin and had no history of VRE in the previous year. Missing data were handled by multiple imputation of 50 datasets. Patients treated with oral vancomycin were compared to those treated with metronidazole after balancing on patient characteristics using propensity score matching in each imputed dataset. Patients were followed for VRE isolated from a clinical culture within 3 months. Results Patients treated with oral vancomycin were no more likely to develop VRE within 3 months than metronidazole-treated patients (adjusted relative risk, 0.96; 95% confidence interval [CI],.77 to 1.20), equating to an absolute risk difference of −0.11% (95% CI, −.68% to.47%). Similar results were observed at 6 months. Conclusions Our results suggest that oral vancomycin and metronidazole are equally likely to impact patients' risk of VRE. In the setting of stable CDI incidence, replacement of metronidazole with oral vancomycin is unlikely to be a significant driver of increased risk of VRE at the patient level. In this multicenter, retrospective cohort study of patients with Clostridioides difficile infection, the use of oral vancomycin did not increase the risk of vancomycin-resistant Enterococci infection at 3 or 6 months compared to metronidazole. [ABSTRACT FROM AUTHOR]

Filter feeding is a biotic process that brings waterborne bacteria in close contact with each other and may thus support the horizontal transfer of their antimicrobial resistance genes. This laboratory study investigated whether the freshwater sponge Ephydatia fluviatilis supported the transfer of vancomycin resistance between two Enterococcus faecalis strains that we previously demonstrated to exhibit pheromone responsive plasmid conjugation. Microcosm experiments exposed live and dead colonies of laboratory‐grown sponges to a vancomycin‐resistant donor strain and a rifampicin‐resistant recipient strain of Ent. faecalis. Enterococci with both resistance phenotypes were detected on double selection plates. In comparison to controls, abundance of these presumed transconjugants increased significantly in water from sponge microcosms. Homogenized suspensions of sponge cells also yielded presumed transconjugants; however, there was no significant difference between samples from live or dead sponges. Fluorescent in situ hybridization analysis of the sponge cell matrix using species‐specific probes revealed the presence of enterococci clusters with cells adjacent to each other. The results demonstrated that sponge colonies can support the horizontal transfer of antimicrobial resistance although the mechanism underlying this process, such as binding of the bacteria to the sponge collagen matrix, has yet to be fully elucidated. [ABSTRACT FROM AUTHOR]

Objectives: VRE are listed, by the WHO, among the leading resistant pathogens causing greatest public concern; hence the spread and transmission of VRE, especially in hospitalized patients, need to be monitored. Despite the advancements in typing methods since the implementation of WGS for outbreak investigations, data interpretation, especially for vancomycin-resistant Enterococcus faecium (VREfm) in an endemic setting, remains challenging. In this study we explored the potential added benefit of incorporating patient movement data and admission screening to accurately estimate the magnitude of an outbreak.Methods: We sequenced 73 VREfm isolates from patients with bacteraemia (n = 43) and rectal colonization (n = 30/32). Genetic relatedness was determined by SNP distance (≤10) between isolates. Patient movements were visualized in a movement network, along with contact intensity and rectal colonization status prior to infection onset.Results: ST117, ST80 and ST203 were the predominant STs in our study population. Forty-four percent (18/41) of VREfm bacteraemia cases were of endogenous origin. SNP analysis of infection and colonization isolates revealed nine clonal groups. Eighty-six percent (37/43) of the patients were visualized in a transmission network due to spatiotemporal overlap. Nineteen out of 43 (44%) belonged to five transmission clusters. Incorporation of prior colonization status revealed that transmission was very likely in only 63% (12/19) of patients in these transmission clusters.Discussion: Although interpretation of WGS data is challenging, incorporation of patient movement data and colonization status by admission screening of high-risk patients may provide additional resolution when interpreting the magnitude of an outbreak in an endemic setting. [ABSTRACT FROM AUTHOR]

Background: Since 2012, the incidence of vancomycin-resistant Enterococcus faecium (VREfm) has increased dramatically in Copenhagen and vanA E. faecium has become endemic and polyclonal.Objectives: To examine whether a patient with a positive VRE clinical sample had the same VREfm in a preceding screening sample (within 60 days).Methods: We performed a 30 month retrospective study. From our laboratory information system (LIS), we identified all patients with an invasive VREfm isolate and a VREfm rectal screening isolate within 60 days before infection. VREfm pairs (screening isolate and invasive isolate) were whole-genome sequenced. All isolates were analysed using SeqSphere and core-genome MLST (cgMLST) types were determined. We examined all isolates for the presence of the three most dominant vanA plasmids in the Capital Region of Denmark. Two novel vanA plasmids were closed by Nanopore/Illumina sequencing.Results: We found a total of 19 VREfm pairs. Of these, 13 patients had pairs with matching cgMLST types and vanA plasmids and a median number of 6 days from identification of carriage to clinical infection. One patient had a pair with non-matching cgMLST types but matching vanA plasmids and 24 days between identification of carriage to clinical infection. Five patients had pairs with non-matching cgMLST types and non-matching vanA plasmids and a median number of 18 days from identification of carriage to clinical infection.Conclusions: Of our 19 pairs, 13 were a match regarding cgMLST types (68%) and 1 more (5%) had matching vanA plasmids. Infection was thus preceded by colonization with the same isolates in 13 out of 19 patients. The five mismatches (26%) could be explained by the longer interval between colonization and infection. [ABSTRACT FROM AUTHOR]

Background Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile infections declined across the UK National Health Service in the decade that followed implementation of an infection control campaign. The national impact on intensive care unit (ICU)-acquired infections has not been documented. Methods Data on MRSA, C. difficile , vancomycin-resistant Enterococcus (VRE), and ICU–acquired bloodstream infections (UABSIs) for 1 189 142 patients from 2007 to 2016 were analyzed. Initial coverage was 139 ICUs increasing to 276 ICUs, representing 100% of general adult UK ICUs. Results ICU MRSA and C. difficile acquisitions per 1000 patients decreased between 2007 and 2016 (MRSA acquisitions, 25.4 to 4.1; and C. difficile acquisitions, 11.1 to 3.5), whereas VRE acquisitions increased from 1.5 to 5.9. There were 13 114 UABSIs in 1.8% of patients who stayed longer than 48 hours on ICU. UABSIs fell from 7.3 (95% confidence interval [CI], 6.9–7.6) to 1.6 (95% CI, 1.5–1.7)/1000 bed days. Adjusting for patient factors, the incidence rate ratio was 0.21 (95% CI, 0.19–0.23, P <.001) from 2007 to 2016. The greatest reduction, comparing rates in 2007/08 and 2015/16, was for MRSA (97%), followed by P. aeruginosa (81%), S. aureus (79%) and Candida spp (72%), with lower reductions for the coliforms (E. coli 57% and Klebsiella 49%). Conclusions Large decreases in ICU-acquired infections occurred across the UK ICU network linked with the first few years of a national infection control campaign, but rates have since been static. Further reductions will likely require a new intervention framework. [ABSTRACT FROM AUTHOR]

Objectives: Infections caused by vancomycin-resistant Enterococcus faecium (VREfm) represent a major public health concern due to limited treatment options. Among invasive isolates of VREfm, ST117, ST80 and ST78 represent the most frequently detected STs by MLST in Germany. In this study, we investigated the genetic diversity of isolates of VREfm recovered from different nosocomial outbreaks in Bavaria, Germany, by WGS.Methods: Between January 2018 and April 2019, 99 non-replicate isolates of VREfm originating from nosocomial outbreaks at eight different hospitals in Bavaria were investigated for genetic diversity by WGS. In detail, complex types (CTs) were identified by core-genome MLST. Furthermore, an SNP analysis was performed for all VREfm strains.Results: Most of the isolates of this study (76%) belonged to three major clonal groups, which occurred in at least three hospitals: ST80/CT1065 vanB (n = 45; six hospitals), ST117/CT71 vanB (n = 11; four hospitals) and ST78/CT894like vanA (n = 19; three hospitals). Moreover, isolates of the predominant lineage ST80/CT1065 vanB showed a maximum difference of 36 SNPs as revealed by SNP analysis.Conclusions: Whole-genome analysis of VREfm causing nosocomial outbreaks suggests the occurrence of few endemic clonal lineages in Bavarian hospital settings, namely ST80/CT1065 vanB, ST117/CT71 vanB and ST78/CT894like vanA. Further studies are needed for a better understanding of the factors affecting the successful spread of the above-mentioned lineages. [ABSTRACT FROM AUTHOR]

Background Vancomycin-resistant enterococci (VRE) are a major cause of hospital-acquired infections. The risk of infection from interventional radiology (IR) procedures is not well documented. Whole-genome sequencing (WGS) surveillance of clinical bacterial isolates among hospitalized patients can identify previously unrecognized outbreaks. Methods We analyzed WGS surveillance data from November 2016 to November 2017 for evidence of VRE transmission. A previously unrecognized cluster of 10 genetically related VRE (Enterococcus faecium) infections was discovered. Electronic health record review identified IR procedures as a potential source. An outbreak investigation was conducted. Results Of the 10 outbreak patients, 9 had undergone an IR procedure with intravenous (IV) contrast ≤22 days before infection. In a matched case-control study, preceding IR procedure and IR procedure with contrast were associated with VRE infection (matched odds ratio [MOR], 16.72; 95% confidence interval [CI], 2.01 to 138.73; P =.009 and MOR, 39.35; 95% CI, 7.85 to infinity; P <.001, respectively). Investigation of IR practices and review of the manufacturer's training video revealed sterility breaches in contrast preparation. Our investigation also supported possible transmission from an IR technician. Infection prevention interventions were implemented, and no further IR-associated VRE transmissions have been observed. Conclusions A prolonged outbreak of VRE infections related to IR procedures with IV contrast resulted from nonsterile preparation of injectable contrast. The fact that our VRE outbreak was discovered through WGS surveillance and the manufacturer's training video that demonstrated nonsterile technique raise the possibility that infections following invasive IR procedures may be more common than previously recognized. [ABSTRACT FROM AUTHOR]

Enterococcus gallinarum and casseliflavus have inherent vancomycin resistance and, though known as pathogens, have not been well characterized in pediatric patients. We identified a significant prevalence of these enterococcal species among immunocompromised patients at a large pediatric institution and describe the impact on patient care, antibiotic stewardship, and infection control. [ABSTRACT FROM AUTHOR]

Objectives: To describe, for the first time (to the best of our knowledge), the genetic mechanisms of vancomycin resistance in clinical isolates of Clostridioides difficile ribotype 027.Methods: Clinical isolates and laboratory mutants were analysed: genomically to identify resistance mutations; by transcriptional analysis of vanGCd, the vancomycin resistance operon encoding lipid II d-alanine-d-serine that is less bound by vancomycin than native lipid II d-alanine-d-alanine; by imaging of vancomycin binding to cell walls; and for changes in vancomycin bactericidal activity and autolysis.Results: Vancomycin-resistant laboratory mutants and clinical isolates acquired mutations to the vanSR two-component system that regulates vanGCd. The substitutions impaired VanSR's function, resulting in constitutive transcription of vanGCd. Resistance was reversed by silencing vanG, encoding d-alanine-d-serine ligase in the vanGCd operon. In resistant cells, vancomycin was less bound to the cell wall septum, the site where vancomycin interacts with lipid II. Vancomycin's bactericidal activity was reduced against clinical isolates and laboratory mutants (64 and ≥1024 mg/L, respectively) compared with WT strains (4 mg/L). Truncation of the potassium transporter TrkA occurred in laboratory mutants, which were refractory to autolysis, accounting for their survival in high drug concentrations.Conclusions: Ribotype 027 evolved first-step resistance to vancomycin by constitutively expressing vanGCd, which is otherwise silent. Experimental evolutions and bactericidal assays show that ribotype 027 can acquire mutations to drastically enhance its tolerance to vancomycin. Thus, further epidemiological studies are warranted to examine the extent to which vancomycin resistance impacts clinical outcomes and the potential for these strains to evolve higher-level resistance, which would be devastating. [ABSTRACT FROM AUTHOR]