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Cefepime-tazobactam (FEP-TAZ) consists of cefepime combined with tazobactam, a penicillanic acid-sulfone recognized as an established beta-lactamase inhibitor. This study aims to investigate the in-vitro effectiveness of FEP-TAZ against cefepime-resistant clinical isolates of Escherichia coli (E. coli). A total of 105 E. coli clinical isolates characterized by cefepime-resistant/susceptible dose-dependent and carbapenem-sensitive profiles were tested for susceptibility by broth microdilution (BMD) method against cefepime and FEP-TAZ (tazobactam at a fixed concentration of 4 mg/L). Minimum inhibitory concentration (MIC) values for cefepime were determined using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method (M100–2022). Simultaneously, we also performed Disk-diffusion (DD) to observe the concordance between BMD and DD. FEP-TAZ exhibited inhibitory efficacy against 83.8% of E. coli isolates, markedly reducing the geometric mean from 20.4 to 1.9. Comparative analysis with DD revealed concordance with MIC for all isolates except four isolates. FEP-TAZ demonstrated potent activity against E.coli. This may be used as a carbapenem-sparing agent for the treatment of serious infections caused by cefepime-resistant Gram-negative bacilli. Furthermore, in settings where BMD implementation poses challenges, the pragmatic application of DD proves to be a viable alternative. [ABSTRACT FROM AUTHOR]

Background: The emergence of antimicrobial resistance in Gram-negative bacteria (GNB) is a major global concern. Ceftazidime–avibactam (CAZ–AVI) has been identified as a potential treatment option for complicated infections. Objectives: This meta-analysis aimed to evaluate the global resistance proportions of GNB to CAZ–AVI comprehensively. Methods: Studies were searched in Scopus, PubMed, and EMBASE (until September 2024), and statistical analyses were conducted using STATA software (version 20.0). Results: CAZ–AVI resistance proportions were determined in 136 studies, with 25.8% (95% CI 22.2–29.7) for non-fermentative gram-negative bacilli and 6.1% (95% CI 4.9–7.4) for Enterobacterales. The CAZ–AVI resistance proportion significantly increased from 5.6% (95% CI 4.1–7.6) of 221,278 GNB isolates in 2015–2020 to 13.2% (95% CI 11.4–15.2) of 285,978 GNB isolates in 2021–2024. Regionally, CAZ–AVI resistance was highest in Asia 19.3% (95% CI 15.7–24.23.4), followed by Africa 13.6% (95% CI 5.6–29.2), Europe 11% (95% CI 7.8–15.2), South America 6.1% (95% CI 3.2–11.5) and North America 5.3% (95% CI 4.2–6.7). Among GNB resistance profiles, colistin-resistant isolates and XDR isolates exhibited the highest resistance proportions (37.1%, 95% CI 14–68 and 32.1%, 95% CI 18.5–49.6), respectively), followed by carbapenem-resistant isolates and MDR isolates [(25.8%, 95% CI 22.6–29.3) and (13%, 95% CI 9.6, 17.3)]. Conclusion: A high proportion of GNB isolates from urinary tract infections remained susceptible to CAZ–AVI, indicating its potential as a suitable treatment option. However, the increasing resistance trends among GNB are concerning and warrant continuous monitoring to maintain CAZ–AVI's effectiveness against GNB infections. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the genetic and clinical characteristics of carbapenem-resistant Enterobacterales (CRE) isolates carrying metallo-β-lactamases (MBLs) genes. Methods: A total of 146 non-duplicated isolates of CRE were collected in 2022. Their ceftazidime/avibactam (CZA) susceptibilities were determined using the E test. The phenotypic identification of carbapenemases was conducted using the modified carbapenem inactivation method, followed by sequencing of the five common carbapenemase genes (blaKPC, blaNDM, blaVIM, blaIMP, and blaOXA-48). Multilocus sequence typing of selected Klebsiella pneumoniae, Escherichia coli, and Enterobacter cloacae complex isolates were performed. Results: Among the 146 CRE isolates, 52 (35.6%) were resistant to CZA. MBL-encoding genes were detected in 46 (31.5%) of all tested CRE isolates, with 82.6% (n = 38) of them exhibiting resistance to CZA. Fourteen isolates were resistant to CZA without any detected MBL genes. The most commonly identified MBL genes were blaIMP (n = 20), followed by blaNDM (n = 19), and blaVIM (n = 5). In CZA-R, the most common definite antibiotic before the CZA E test was CZA (n = 18), followed by tigecycline (n = 13), and fluroquinolone (n = 10). The 14-day and 30-day mortality rates were 9.0% (n = 13) and 22.8% (n = 34), and were associated with intensive care unit admission at onset (P = 0.029 and P = 0.001, respectively). The sequence types of CRE isolates carrying MBLs were diverse without major clones. Conclusion: The continuous emergence of MBL gene-encoding CRE with multiple clones has led to reduced CZA susceptibilities and worse outcomes. [ABSTRACT FROM AUTHOR]

Antibiotic resistance poses a significant global threat, particularly in the context of bloodstream infections. Early antimicrobial susceptibility testing plays a crucial role in guiding clinicians to optimize treatment and enhance patient outcomes. Direct disk diffusion testing (dDDT), utilizing positive blood culture broth as an inoculum, provides results one day earlier than the standard method using bacterial colonies. This retrospective study evaluated the ability of dDDT to predict nonsusceptibility to commonly used antibiotics. From January 2021 to December 2023, a total of 1473 blood cultures positive for a single pathogen (Enterobacterales, Pseudomonas aeruginosa, Staphylococcus aureus, β-hemolytic streptococci, or Enterococcus spp.) were examined. The results of dDDT were compared against the standard disk diffusion method as the reference standard. A total of 9754 organism–antibiotic pairs were analyzed. The positive predictive values were more than 98% for clinically significant resistant phenotypes, including ceftriaxone, ceftazidime, cefepime, and meropenem nonsusceptibility in Enterobacterales, ceftazidime and meropenem nonsusceptibility in P. aeruginosa, and cefoxitin resistance in S. aureus. Overall, sensitivities exceeded 98% for the majority of organism–antibiotic pairs, with specificities ranging from 88.4% to 100%. Categorical agreement was high at 97.9%, ranging from 88.8% to 100% across organism groups. The overall rates of major error and very major error were very low, at 0.2% and 0.04%, respectively, and ranged from 0% to 1.5% and 0% to 0.04%, respectively, across organism groups. In conclusion, dDDT is a reliable and expedient method for detecting antibiotic nonsusceptibility, making it a valuable tool for the timely management of bloodstream infections caused by resistant organisms. [ABSTRACT FROM AUTHOR]

Purpose: Infective endocarditis caused by non-HACEK gram-negative bacilli (GNB-IE) is rare but associated with significant morbidity and case fatality. Evidence on optimal treatment and management is limited. We aimed to describe the characteristics and management of GNB-IE patients, investigating factors associated with disease acquisition and unfavorable outcomes. Methods: We conducted a retrospective descriptive single-center study (tertiary care and referral hospital) between 2015 and 2021, including adult patients with definite GNB-IE. We reviewed demographic, clinical and microbiological data, focusing on predisposing factors, clinical outcomes and 1-year mortality. Results: Of 1093 patients with probable or definite IE, 19 patients (median age 69 years) had definite GNB-IE, with an increasing incidence throughout the study period. Median age-adjusted Charlson Comorbidity Index score was 4 points. Prosthetic valve IE (PVIE) was present in 7/19 (37%) patients. Nosocomial acquisition occurred in 8/19 (42%) patients. Escherichia coli and Klebsiella pneumoniae were the most common pathogens. Beta-lactam (BL) based combination therapy was applied in 12/19 (63%) patients (58% BL + fluoroquinolone, 42% BL + aminoglycoside). Cardiac surgery was required in 8/19 (42%) patients (PVIE 71%, native valve IE 25%), primarily for embolism prevention and heart failure. Complications occurred in 14/19 (74%) patients. The in-hospital mortality rate was 21% (4/19); the one-year mortality rate was 44% (7/16). One-year mortality did not significantly differ between patients who underwent cardiac surgery and patients managed with anti-infective treatment alone (p = 0.633). Conclusions: GNB-IE affects elderly patients with high comorbidity levels and recent health-care exposure. GNB-IE was associated with high complication rates and high mortality. [ABSTRACT FROM AUTHOR]

Background: Initial antimicrobial therapy for pneumonia is frequently empirical and resistance to antimicrobial agents represents a great challenge to the treatment of patients hospitalized with pneumonia. We evaluated the frequency and antimicrobial susceptibility of Gram-negative bacteria causing pneumonia in US hospitals. Methods: Bacterial isolates were consecutively collected (1/patient) from patients hospitalized with pneumonia and the susceptibility of Gram-negative bacilli (3,911 Enterobacterales and 2,753 non-fermenters) was evaluated by broth microdilution in a monitoring laboratory. Isolates were collected in 69 medical centers in 2020–2022. Aztreonam-avibactam was tested with avibactam at fixed 4 mg/L and a pharmacokinetic/pharmacodynamic susceptible (S) breakpoint of ≤ 8 mg/L was applied for comparison. Carbapenem-resistant Enterobacterales (CRE; isolates with MIC values of > 2 mg/L for imipenem and/or meropenem) isolates were screened for carbapenemases by whole genome sequencing. Results: Gram-negative bacilli represented 71.1% of organisms. The most common Gram-negative species were Pseudomonas aeruginosa (22.4% of organisms), Klebsiella pneumoniae (8.8%), Escherichia coli (6.6%), Serratia marcescens (6.2%), Stenotrophomonas maltophilia (4.9%), and Enterobacter cloacae complex (4.8%). Aztreonam-avibactam inhibited 100.0% of Enterobacterales at ≤ 8 mg/L and 99.9% at ≤ 4 mg/L and showed potent activity against CRE (MIC50/90, 0.25/1 mg/L). Ceftazidime-avibactam and meropenem-vaborbactam were active against 89.4% and 88.5% of CREs, respectively. Aztreonam-avibactam retained activity against Enterobacterales non-susceptible to ceftazidime-avibactam and/or meropenem-vaborbactam (n = 19; MIC50/90, 0.25/4 mg/L). The most common carbapenemases were KPC (69.2% of CREs), NDM (9.6%), and SME (4.8%). A carbapenemase gene was not identified in 16.3% of CREs. Ceftazidime-avibactam and meropenem-vaborbactam were highly active against KPC and SME producers but showed limited activity against MBL producers. The most active comparators against CRE were tigecycline (95.2%S), amikacin (73.1%S), and gentamicin (60.6%S). Among Pseudomonas aeruginosa, 79.1% were inhibited at ≤ 8 mg/L of aztreonam-avibactam, 77.2% were meropenem susceptible, and 77.2% were piperacillin-tazobactam susceptible. Aztreonam-avibactam was highly active against S. maltophilia, inhibiting 99.5% of isolates at ≤ 8 mg/L. Conclusions: Aztreonam-avibactam displayed potent in vitro activity against a large collection of contemporary Gram-negative organisms isolated from patients hospitalized with pneumonia, including CRE isolates resistant to ceftazidime-avibactam and/or meropenem-vaborbactam. Results of surveillance programs are valuable for planning empiric antimicrobial therapy guidelines and infection control measures. [ABSTRACT FROM AUTHOR]

From a One Health perspective, dogs and cats have begun to be recognized as important reservoirs for clinically significant multidrug-resistant bacterial pathogens. In this study, we investigated the occurrence and genomic features of ESβL producing Enterobacterales isolated from dogs, in the province of Imbabura, Ecuador. We identified four isolates expressing ESβLs from healthy and diseased animals. In this regard, two Escherichia coli strains producing CTX-M-55-like or CTX-M-65 ESβLs belonged to the international ST10 and ST162, whereas two Klebsiella pneumoniae producing CTX-M-14 or CTX-M-27 belonged to ST35 and ST661. Phylogenomic analysis clustered (95-105 SNP differences) CTX-M-55/ST10 E. coli from companion animal with food and human E. coli strains of ST10 isolated in 2016, in Australia and Cambodia, respectively; whereas CTX-M-27-positive K. pneumoniae ST661 was clustered (201-216 SNP differences) with human strains identified in Italy, in 2013 and 2017, respectively. In summary, we report the presence and genomic data of global human-associated clones of CTX-M-producing E. coli and K. pneumoniae in dogs, in Ecuador. The implementation of a national epidemiological surveillance program is necessary to establish future strategies to control the dissemination of antibiotic-resistant priority pathogens using a One Health approach. [ABSTRACT FROM AUTHOR]

Introduction: The global rise of extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE) challenges resource-limited countries with insufficient laboratory infrastructure. This study investigates fecal carriage and risk factors for ESBL-PE and carbapenemase-producing organisms among patients with urinary tract infection (UTI) in rural Tanzania. Methods: This cross-sectional study was conducted at St. Francis Regional Referral Hospital, Ifakara, Tanzania, from October 2021 to August 2023, involving 326 UTI patients. Demographic data and resistance risk factors were collected via structured questionnaires. Stool samples collected pre-antibiotic treatment were screened for ESBL-PE and carbapenemase locally. Positive samples underwent further analysis in Switzerland using MALDI-ToF, Vitek MS, and whole-genome sequencing. Multivariable analysis assessed predictors associated with ESBL-PE carriage for risk factors with p < 0.05. Results: We enrolled 326 UTI patients (median age: 35.5 years, range: 25–52) and 189 (58.0%) were females. Fecal ESBL-PE colonization was detected in 70.9% of patients, predominantly E. coli (62.8%) and K. pneumoniae (33.0%). Whole-genome sequencing identified diverse phylogroups and sequence types, with CTX-M-15 being the most common ESBL gene. IncF plasmids were the primary carriers. Younger age (aOR: 0.98, 95% CI: 0.97–0.99; p = 0.0239) and inpatient status (aOR: 1.77, 95% CI: 1.08–2.91; p = 0.0036) were significant risk factors for ESBL-PE carriage. Conclusion: The high prevalence of ESBL-PE fecal carriage in rural Tanzania highlights the need for improved infection control and further research into community transmission dynamics. [ABSTRACT FROM AUTHOR]

Objectives To evaluate the in vitro susceptibility of recent Gram-negative pathogens collected from pediatric patients to imipenem/relebactam (IMI/REL) and comparator agents. Methods From 2018 to 2022 254 hospitals in 62 countries collected Enterobacterales or Pseudomonas aeruginosa isolates from patients <18 years old as part of the SMART global surveillance program. Minimum inhibitory concentrations (MIC)s were determined using CLSI broth microdilution and interpreted with 2024 CLSI breakpoints. Most isolates non-susceptible to IMI/REL were queried for their acquired β-lactamase content. Results Overall, 96.8% of all non- Morganellaceae Enterobacterales (NME) isolates from pediatric patients (n  = 12 060) were IMI/REL-susceptible. Most NME were also susceptible to imipenem alone (93.9%), meropenem (96.0%), and ertapenem (94.4%); isolates were less susceptible to piperacillin/tazobactam (82.8%), cefepime (76.3%), and ceftazidime (74.4%). Non- Morganellaceae Enterobacterales collected in Asia were the least susceptible to IMI/REL (91.6%), while those from Australia/New Zealand were the most (99.3%). Imipenem/relebactam was equally potent against NME isolates regardless of infection source, hospital ward, age, and length of hospitalization. In total, 90.8% of all Pseudomonas aeruginosa isolates (n  = 3046) were IMI/REL-susceptible; ceftolozane/tazobactam also inhibited >90% of the P. aeruginosa. Regionally, P. aeruginosa isolates from Eastern Europe were least susceptible to IMI/REL. Molecular characterization revealed that, globally, most resistance to IMI/REL among the NME could be attributed to the presence of NDM-type metallo-β-lactamases, while no acquired β-lactamases were detected in approximately half the IMI/REL non-susceptible P. aeruginosa examined. Conclusion Based on in vitro data, IMI/REL represents a good therapeutic option for most hospitalized pediatric patients infected with common Gram-negative pathogens. [ABSTRACT FROM AUTHOR]

ABSTRACT: Background: Multidrug resistant (MDR) Gram negative organisms are becoming increasingly common. Carbapenem resistant Enterobacterales (CRE) pose a major threat and necessitate the development of new antibiotics. MDR and carbapenem resistant infections, which are common in intensive care units and hospitals, lead to increased morbidity, mortality, prolonged hospital stays, and higher healthcare costs. New antimicrobials such as ceftazidime avibactam offer potential alternatives to conventional treatments such as tigecycline and colistin, which have significant side effects and limitations. Aim: This study focuses on the antibiotic susceptibility of ceftazidime/ avibactam to Gram negative bacilli found in a large number of clinical samples collected from a tertiary care facility in Netaji Subhas Medical University and Hospital, Bihta, India. Methodology: The study included 81 Gram negative bacteria isolated from patient samples. Based on the Clinical Laboratory Standards Institute guidelines mentioned in the Kirby Bauer disc diffusion method. Result and Conclusion: the results showed that ceftazidime avibactam inhibited 89.9% of the Enterobacteriaceae isolates, which was higher than the 80.3% of amikacin and the 85.1% of meropenem. Ceftazidime avibactam was effective against CRE isolates in 69.9% of cases and against MDR isolates in urine in 94% of cases, which was higher than the 40% of ceftriaxone and 94% of nitrofurantoin. The results show that ceftazidime avibactam can cure MDR and CRE infections, especially urinary tract infections, better than conventional antibiotics, which is a great help in the fight against increasing antibiotic resistance. [ABSTRACT FROM AUTHOR]

Background: Monomicrobial Enterobacterales necrotizing fasciitis is associated with exceedingly high mortality rates. Although effective antimicrobial therapy is an important part of treatment, the traditional microbiological diagnostic methods are not fast enough to meaningfully influence early therapeutic decisions. Methods: Here, we report the application of the BioMérieux Biofire Filmarray Joint Infection Panel (BFJIP) for the rapid detection of the causative agent and susceptibility prediction in such a case. Aside from the BFJIP-based rapid diagnostic approach and culturing, the whole genome sequencing (WGS) of the causative agent was performed using Illumina MiSeq and Oxford Nanopore MinION platforms. Results: The BFJIP indicated the presence of K. pneumoniae, without KPC, VIM, IMP, NDM, OXA-48 carbapenemase genes, and CTX-M-type extended-spectrum beta-lactamases. Based on the WGS data, the isolate belonged to the K1-capsule-type ST23, harboured a pNTUH-2044-like plasmid, and was positive for all the virulence factors associated with this lineage. The conventional susceptibility results were also in accordance with the BFJIP results; the isolate lacked any of these acquired resistance mechanisms. Conclusions: Despite this being the first case of the successful identification of pathogenic bacteria in necrotising fasciitis using this assay, the BFJIP may become a useful tool for rapid identification of pathogens in necrotising fasciitis cases and guiding antimicrobial therapy for better clinical outcomes. [ABSTRACT FROM AUTHOR]

An advanced biochemical assay named modified Carba PBP test was innovated to identify and differentiate distinct categories of clinically significant carbapenemases (Ambler classes A, B, and D) within the Enterobacterales. The mechanism of mCarba PBP hinges on two core attributes: (i) the hydrolysis of the meropenem substrate by various carbapenemases, (ii) the immobilized penicillin and free meropenem in their affinity to interact with a limited quantity of penicillin-binding protein (PBP). Specific inhibitors for class A (phenylboronic acid, PBA) and class B (ethylenediaminetetraacetic acid, EDTA) were employed to inhibit the hydrolysis activity of carbapenemase and facilitate the classification of carbapenemase classes within 25 min. A comprehensive evaluation was undertaken using 94 clinical Enterobacterales isolates, comprising 75 carbapenemase-producing strains and 19 non-carbapenemase-producing strains. Its overall specificity and sensitivity were 100% and 97.3%, respectively, including detection of all types of OXA-48-like carbapenemases. For precise carbapenemase type identification, the assay exhibited remarkable sensitivities for class A, class B, and class D detection at 94.7%, 100%, and 100%, respectively. This user-friendly test presents a promising tool for carbapenemase identification, refining the selection of β-lactam/β-endoenzyme inhibitor combinations for effectively treating infections due to carbapenemase-producing organisms. [ABSTRACT FROM AUTHOR]

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Abstract Background Initial antimicrobial therapy for pneumonia is frequently empirical and resistance to antimicrobial agents represents a great challenge to the treatment of patients hospitalized with pneumonia. We evaluated the frequency and antimicrobial susceptibility of Gram-negative bacteria causing pneumonia in US hospitals. Methods Bacterial isolates were consecutively collected (1/patient) from patients hospitalized with pneumonia and the susceptibility of Gram-negative bacilli (3,911 Enterobacterales and 2,753 non-fermenters) was evaluated by broth microdilution in a monitoring laboratory. Isolates were collected in 69 medical centers in 2020–2022. Aztreonam-avibactam was tested with avibactam at fixed 4 mg/L and a pharmacokinetic/pharmacodynamic susceptible (S) breakpoint of ≤ 8 mg/L was applied for comparison. Carbapenem-resistant Enterobacterales (CRE; isolates with MIC values of > 2 mg/L for imipenem and/or meropenem) isolates were screened for carbapenemases by whole genome sequencing. Results Gram-negative bacilli represented 71.1% of organisms. The most common Gram-negative species were Pseudomonas aeruginosa (22.4% of organisms), Klebsiella pneumoniae (8.8%), Escherichia coli (6.6%), Serratia marcescens (6.2%), Stenotrophomonas maltophilia (4.9%), and Enterobacter cloacae complex (4.8%). Aztreonam-avibactam inhibited 100.0% of Enterobacterales at ≤ 8 mg/L and 99.9% at ≤ 4 mg/L and showed potent activity against CRE (MIC50/90, 0.25/1 mg/L). Ceftazidime-avibactam and meropenem-vaborbactam were active against 89.4% and 88.5% of CREs, respectively. Aztreonam-avibactam retained activity against Enterobacterales non-susceptible to ceftazidime-avibactam and/or meropenem-vaborbactam (n = 19; MIC50/90, 0.25/4 mg/L). The most common carbapenemases were KPC (69.2% of CREs), NDM (9.6%), and SME (4.8%). A carbapenemase gene was not identified in 16.3% of CREs. Ceftazidime-avibactam and meropenem-vaborbactam were highly active against KPC and SME producers but showed limited activity against MBL producers. The most active comparators against CRE were tigecycline (95.2%S), amikacin (73.1%S), and gentamicin (60.6%S). Among Pseudomonas aeruginosa, 79.1% were inhibited at ≤ 8 mg/L of aztreonam-avibactam, 77.2% were meropenem susceptible, and 77.2% were piperacillin-tazobactam susceptible. Aztreonam-avibactam was highly active against S. maltophilia, inhibiting 99.5% of isolates at ≤ 8 mg/L. Conclusions Aztreonam-avibactam displayed potent in vitro activity against a large collection of contemporary Gram-negative organisms isolated from patients hospitalized with pneumonia, including CRE isolates resistant to ceftazidime-avibactam and/or meropenem-vaborbactam. Results of surveillance programs are valuable for planning empiric antimicrobial therapy guidelines and infection control measures.

ABSTRACT Uncomplicated bacteremic urinary tract infections (bUTIs) are common, often caused by Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecalis, with most encounters treated empirically. As rates of antimicrobial resistance increase, available antibiotic treatment options are dwindling. Novel antibiotics approved for treating bUTIs are limited, leading to a resurgence of interest in older antibiotics, including fosfomycin. Here, clinical urine samples from patients including military personnel, retirees, and their dependents diagnosed with bUTIs from a military hospital located in Bethesda, Maryland, were tested for susceptibility to fosfomycin and comparator antibiotics (levofloxacin, nitrofurantoin, and trimethoprim-sulfamethoxazole [TMS]). A total of 1,353 nonduplicate bacterial isolates were tested, including 605 non-ESBL and 285 ESBL E. coli, and 84 non-ESBL and 52 ESBL K. pneumoniae. Fosfomycin susceptibility rates were similar for non-ESBL and ESBL E. coli (95.9% vs 96.1%) and K. pneumoniae (38.1% vs 36.5%). Fosfomycin demonstrated high activity against other Enterobacterales and gram-positive organisms including Enterobacter faecalis and Staphylococcus aureus. Interestingly, most fosfomycin non-susceptible isolates were susceptible to other first-line bUTI treatment options, and most isolates that were non-susceptible to other first-line bUTI treatment option were susceptible to fosfomycin. ESBL K. pneumoniae isolates were the least susceptible to current first-line treatment options. Fosfomycin Etest demonstrated high sensitivity compared to agar dilution, making it a viable AST testing method especially in resource-limited areas. Overall, we demonstrated fosfomycin has high activity against common etiologies that cause bUTIs. Further clinical efficacy studies investigating the use of fosfomycin in treating non-E. coli bUTI pathogens, as single or combination therapy, are warranted.IMPORTANCEUncomplicated bUTIs are often caused by Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecalis. Fosfomycin is one of the recommended firstline antibiotics for the treatment of symptomatic, uncomplicated bUTIs. Fosfomycin susceptibility testing is complicated by the fact that although both CLSI and EUCAST recognize agar dilution (AD) as the reference method albeit being labor-intensive, breakpoints are different, and Etest is only approved by EUCAST. We investigated the susceptibility of bUTI clinical isolates to fosfomycin using AD and compared performance in a subset of isolates to Etest. Fosfomycin susceptibility profiles of bacterial isolates were compared to other firstline antibiotics. We found isolates were susceptible to fosfomycin at similar or higher rates compared to other firstline antibiotics. Importantly, fosfomycin was effective against isolates producing extended-spectrum beta-lactamases and those that were resistant to other firstline treatments. Furthermore, our data showed Etest was a viable option for susceptibility testing with 94% agreement to the AD.

Summary: Background: Carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa (CRPA), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) are listed by World Health Organization (WHO) as priority antimicrobial-resistant bacteria. Data on WHO Priority Antimicrobial resistance Phenotype (WPAP) bacteria from low- and middle-income countries are scarce. In this study, we investigated the occurrence of WPAP in healthcare-associated bloodstream infections (BSI) in Brazil, an upper-middle-income country in South America. Methods: ASCENSION was a prospective, multicentre, observational study conducted in 14 hospitals from four of five Brazilian regions. Enterobacterales, A. baumannii, P. aeruginosa, S. aureus and E. faecium BSIs in hospitalised patients were analysed. The primary outcome was the frequency of WPAP among all bacteria of interest. Secondary outcomes were incidence-density of bacteria isolates in hospitalised patients, WPAP proportions within bacterial species, and 28-day mortality. PCR for carbapenemase genes was performed in carbapenem-resistant Gram-negative bacteria. Findings: Between August 15, 2022, and August 14, 2023, 1350 isolates (1220 BSI episodes) were included. WPAP accounted for 38.8% (n = 524; 95% Confidence Interval 32.0–46.1) of all isolates, with CRE (19.3%) as the most frequent, followed by CRAB (9.6%), MRSA (4.9%), VRE (2.7%), and CRPA (2.4%). Incidence-density of all and WPAP isolates were 1.91 and 0.77/1000 patients-day, respectively. Carbapenem-resistant Klebsiella pneumoniae (CRKP) was the most common CRE, corresponding to 14.2% of all BSIs. A. baumannii isolates presented the highest proportion of WPAP (87.8%). Mortality rates were higher in patients with BSIs by WPAP than non-WPAP isolates. KPC (64.4%) was the predominant carbapenemase in CRE, followed by NDM (28.4%) and KPC + NDM co-production (7.1%). OXA-23 was the most frequent in CRAB. Interpretation: A high frequency of WPAP bacteria, particularly CRKP and CRAB, were found in healthcare-associated BSIs in Brazil, posing them as a major public health problem in this country. Funding: National Council for Scientific and Technological Development, Brazil.

Introducción El surgimiento de microorganismos multidrogoresistentes [MDR] se ha convertido en un problema sanitario a nivel mundial. En este grupo se encuentran los Enterobacterales productores de Betalactamasas de Espectro Extendido [EBLEE] los cuales son agentes etiológicos de procesos infecciosos tanto comunitarios como intrahospitalarios graves. Estas bacterias pertenecientes al microbiota intestinal han ido generando resistencia debido al uso indiscriminado de antibióticos, causando así infecciones graves como bacteriemias, neumonías, infecciones urinarias, infecciones intra-abdominales, entre otras. El objetivo de nuestro estudio fue identificar fenotípicamente EBLEE aisladas de pacientes del Hospital General Isidro Ayora, de la ciudad de Loja. Materiales y métodos En el presente estudio se analizó 862 muestras biológicas de heces fecales e hisopados rectales procedentes de pacientes de las áreas de Consulta Externa, Hospitalización y la Unidad de Cuidados Intensivos [UCI] del Hospital General Isidro Ayora, de la ciudad de Loja. El periodo de muestreo fue de noviembre 2022 hasta agosto 2023. Siembra de muestras Las muestras fueron sembradas en medios de cultivo diferenciales: CHROMagar™ ESBL, específico para EBLEE. Identificación de BLEE Se realizaron dos pruebas de identificación: prueba de sinergia de doble disco y prueba de discos combinados con inhibidor en Agar Müller-Hinton. Para la primera prueba se empleó los antibióticos: Amoxicilina + Ácido clavulánico [AMC] (30 µg), Cefotaxima [CTX] (30 µg) o Ceftriaxona [CRO] (30 µg), Cefepime [FEP] (30 µg), Ceftazidima [CAZ] (30 µg), Aztreonam [ATM] (30 µg). Para la segunda prueba se empleó: Ceftriaxona [CRO] (30 µg), Cefotaxima [CTX] (30 µg) Cefotaxima + Ácido clavulánico (CTX+CLA) (30 µg). Las pruebas se incubaron a 37 ± 2 °C durante 18 a 24 horas. Las pruebas de identificación se basaron en los protocolos establecidos por el CLSI 2022. Identificación bacteriana Para este proceso se empleó el Kit Enterosystem 18R, cuyo protocolo de identificación fue de acuerdo con las especificaciones comerciales del proveedor. Resultados Se aislaron un total de 200 cepas EBLEE. Las especies bacterianas con mayor incidencia en la población evaluada fueron Escherichia coli 83% (166/200); Klebsiella pneumoniae 6,5% (13/200); Serratia liquefaciens 2,5% (5/200) y otras enterobacterias con un 8%(16/200). Conclusiones Es uno de los primeros estudios realizados en la ciudad de Loja que contribuirá al conocimiento local respecto a resistencia bacteriana, además de que apunta a futuras investigaciones moleculares que podrían ofrecer nuevas perspectivas respecto al impacto y manejo de estas bacterias resistentes que se han convertido en un problema sanitario de interés.

ABSTRACT Carbapenem-resistant Enterobacterales (CRE) are divided into two distinct groups: carbapenemase-producing (CPE) and non-carbapenemase-producing (non-CPE). The population of non-CPE growing on CPE selective plates during routine screening is usually not reported and is not well defined. This study aimed to characterize non-CPE isolates growing on those plates. Isolates were collected from two medical institutions in Israel between May and November 2022. Species identification and antibiotic susceptibility testing were performed using VITEK systems. Further analyses focused on Klebsiella pneumoniae and Escherichia coli which were the most common isolates. Meropenem MIC was determined by E-test. Fourier-transform infrared spectroscopy (FTIR) was used to analyze phenotypic similarity, and whole genome sequencing was conducted on a subset of non-CPE isolates. Of 260 isolates growing on selective CPE screening plates, 60.4% were non-CPE. The most common non-CP isolates were K. pneumoniae (65.6%) followed by E. coli (20.4%). Of the non-CP K. pneumoniae and E. coli isolates, 78.2% were susceptible to meropenem. All non-CP K. pneumoniae and E. coli isolates were multidrug-resistant (MDR) and belonged to multiple FTIR clusters. The 21 sequenced non-CPE isolates carried multiple mechanisms of resistance. Isolates had multiple beta-lactamases and all had penicillin-binding protein modifications and porin mutations; in meropenem-resistant K. pneumoniae isolates, both Ompk35 and Ompk36 were mutated. The majority of isolates growing on selective CPE screening plates are non-CPE but are MDR. Laboratory reporting of these MDR bacteria might be useful for guiding treatment and prophylaxis when indicated, as well as for infection control.IMPORTANCESelective screening plates for carbapenemase-producing Enterobacterales (CPE) are used to detect CPE carriers for infection control purposes. We characterized non-CPE isolates that grew on selective CPE screening plates, which are intended to filter them out. We found that 60% of isolates that grew on these plates were not CPE. They included both meropenem-susceptible and meropenem-resistant isolates and were multidrug-resistant with multiple resistance mechanisms. These test results, which are usually not reported by laboratories, may be clinically valuable.

ABSTRACT Pantoea eucrina, a member of the Erwiniaceae family, is a rarely reported human pathogen primarily associated with plants. This study presents a documented case of catheter‐related bloodstream infection caused by P. eucrina in a 60‐year‐old female receiving home parenteral nutrition. Despite presenting with only minor clinical symptoms, blood cultures from both central and peripheral sites confirmed the presence of P. eucrina, identified by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) and whole‐genome sequencing. The infection was successfully cleared following a 13‐day course of gentamicin lock therapy and intravenous piperacillin–tazobactam, after which the catheter was removed.

Background: The global spread of carbapenemase-producing Enterobacterales (CPE) and the increasing emergence of clinical Enterobacterales harboring multiple carbapenemases of different molecular classes have prioritized the use of rapid molecular detection methods in routine microbiology laboratories. The aim of this study was to evaluate the applicability of the immunochromatographic O. K.N.V.I. RESIST-5 and the KPC&MBL&0XA-48 disc tests in a clinical microbiology laboratory. Material and methods: The tests were performed with 50 CPE belonging to 8 species and producing 7 molecularly characterized carbapenemases. Six of these isolates carried two different carbapenemases. To assess the specificity of the assays, 18 non-carbapenemase-producing but carbapenem-resistant Enterobacterales (non-CP CRE) were also included. Both tests were performed from a common overnight culture on Mueller-Hinton agar with inoculum harvested around an ertapenem disk. Results: The O.K.N.V.I. RESIST-5 correctly detected all 56 carbapenemases, including KPC-2 in Klebsiella pneumoniae; OX-48 in Serratia marcescens, Citrobacter freundii, Enterobacter hormaechei and K. pneumoniae; NDM-1 in Escherichia coli, Morganella morganii, E. hormaechei, C. freundii, S. marcescens and K. pneumoniae; VIM-1 in Proteus mirabilis; VIM-4 in C. freundii and S. marcescens; VIM-86 with and without NDM-1 in Providencia stuartii, and NDM-5 with and without OXA-232 in K. pneumoniae. The KPC&MBL&0XA-48 disc tests correctly confirmed KPC, OX-48-like and most MBL except VIM in P. mirabilis. Furthermore, the combination disc tests failed to detect OXA-48-like in pairs with MBL in K. pneumoniae. Conclusions:The O.K.N.V.I. RESIST-5 multiplex lateral assay is an excellent test for rapid diagnostic of CPE in routine microbiology laboratories. It is easy to handle and provides results with 100% sensitivity and specificity when an inoculum around ertapenem disc from routine antibiogram was used.

IntroductionThe global rise of extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE) challenges resource-limited countries with insufficient laboratory infrastructure. This study investigates fecal carriage and risk factors for ESBL-PE and carbapenemase-producing organisms among patients with urinary tract infection (UTI) in rural Tanzania.MethodsThis cross-sectional study was conducted at St. Francis Regional Referral Hospital, Ifakara, Tanzania, from October 2021 to August 2023, involving 326 UTI patients. Demographic data and resistance risk factors were collected via structured questionnaires. Stool samples collected pre-antibiotic treatment were screened for ESBL-PE and carbapenemase locally. Positive samples underwent further analysis in Switzerland using MALDI-ToF, Vitek MS, and whole-genome sequencing. Multivariable analysis assessed predictors associated with ESBL-PE carriage for risk factors with p

From a One Health perspective, dogs and cats have begun to be recognized as important reservoirs for clinically significant multidrug-resistant bacterial pathogens. In this study, we investigated the occurrence and genomic features of ESβL producing Enterobacterales isolated from dogs, in the province of Imbabura, Ecuador. We identified four isolates expressing ESβLs from healthy and diseased animals. In this regard, two Escherichia coli strains producing CTX-M-55-like or CTX-M-65 ESβLs belonged to the international ST10 and ST162, whereas two Klebsiella pneumoniae producing CTX-M-14 or CTX-M-27 belonged to ST35 and ST661. Phylogenomic analysis clustered (95-105 SNP differences) CTX-M-55/ST10 E. coli from companion animal with food and human E. coli strains of ST10 isolated in 2016, in Australia and Cambodia, respectively; whereas CTX-M-27-positive K. pneumoniae ST661 was clustered (201-216 SNP differences) with human strains identified in Italy, in 2013 and 2017, respectively. In summary, we report the presence and genomic data of global human-associated clones of CTX-M-producing E. coli and K. pneumoniae in dogs, in Ecuador. The implementation of a national epidemiological surveillance program is necessary to establish future strategies to control the dissemination of antibiotic-resistant priority pathogens using a One Health approach.

ABSTRACT Carbapenemase-producing Enterobacterales (CPE) is a diverse group of often multidrug-resistant organisms. Surveillance and control of infections are complicated due to the inter-species spread of carbapenemase-encoding genes (CEGs) on mobile genetic elements (MGEs), including plasmids and transposons. Due to wastewater discharges, urban water ecosystems represent a known reservoir of CPE. However, the dynamics of carbapenemase-bearing MGE dissemination between Enterobacterales in humans and environmental waters are poorly understood. We carried out whole-genome sequencing, combining short- and long-sequencing reads to enable complete characterization of CPE isolated from patients, wastewaters, and natural waters between 2018 and 2020 in Galway, Ireland. Isolates were selected based on their carriage of Class A blaKPC-2 (n = 6), Class B blaNDM-5 (n = 12), and Class D blaOXA-48 (n = 21) CEGs. CEGs were plasmid-borne in all but two isolates. OXA-48 dissemination was associated with a 64 kb IncL plasmid (62%), in a broad range of Enterobacterales isolates from both niches. Conversely, blaKPC-2 and blaNDM-5 genes were usually carried on larger and more variable multireplicon IncF plasmids in Klebsiella pneumoniae and Escherichia coli, respectively. In every isolate, each CEG was surrounded by a gene-specific common genetic environment which constituted part, or all, of a transposable element that was present in both plasmids and the bacterial chromosome. Transposons Tn1999 and Tn4401 were associated with blaOXA-48 and blaKPC-2, respectively, while blaNDM-5 was associated with variable IS26 bound composite transposons, usually containing a class 1 integron.IMPORTANCESince 2018, the Irish National Carbapenemase-Producing Enterobacterales (CPE) Reference Laboratory Service at University Hospital Galway has performed whole-genome sequencing on suspected and confirmed CPE from clinical specimens as well as patient and environmental screening isolates. Understanding the dynamics of CPE and carbapenemase-encoding gene encoding mobile genetic element (MGE) flux between human and environmental reservoirs is important for One Health surveillance of these priority organisms. We employed hybrid assembly approaches for improved resolution of CPE genomic surveillance, typing, and plasmid characterization. We analyzed a diverse collection of human (n = 17) and environmental isolates (n = 22) and found common MGE across multiple species and in different ecological niches. The conjugation ability and frequency of a subset of these plasmids were demonstrated to be affected by the presence or absence of necessary conjugation genes and by plasmid size. We characterize several MGE at play in the local dissemination of carbapenemase genes. This may facilitate their future detection in the clinical laboratory.

Antibiotic resistance poses a significant global threat, particularly in the context of bloodstream infections. Early antimicrobial susceptibility testing plays a crucial role in guiding clinicians to optimize treatment and enhance patient outcomes. Direct disk diffusion testing (dDDT), utilizing positive blood culture broth as an inoculum, provides results one day earlier than the standard method using bacterial colonies. This retrospective study evaluated the ability of dDDT to predict nonsusceptibility to commonly used antibiotics. From January 2021 to December 2023, a total of 1473 blood cultures positive for a single pathogen (Enterobacterales, Pseudomonas aeruginosa, Staphylococcus aureus, β-hemolytic streptococci, or Enterococcus spp.) were examined. The results of dDDT were compared against the standard disk diffusion method as the reference standard. A total of 9754 organism–antibiotic pairs were analyzed. The positive predictive values were more than 98% for clinically significant resistant phenotypes, including ceftriaxone, ceftazidime, cefepime, and meropenem nonsusceptibility in Enterobacterales, ceftazidime and meropenem nonsusceptibility in P. aeruginosa, and cefoxitin resistance in S. aureus. Overall, sensitivities exceeded 98% for the majority of organism–antibiotic pairs, with specificities ranging from 88.4% to 100%. Categorical agreement was high at 97.9%, ranging from 88.8% to 100% across organism groups. The overall rates of major error and very major error were very low, at 0.2% and 0.04%, respectively, and ranged from 0% to 1.5% and 0% to 0.04%, respectively, across organism groups. In conclusion, dDDT is a reliable and expedient method for detecting antibiotic nonsusceptibility, making it a valuable tool for the timely management of bloodstream infections caused by resistant organisms.

Globalization in the 21st century has posed several challenges. In particular, the spread of multidrug-resistant bacterial strains, especially Gram-negative bacteria, which are prevalent in certain regions of the world, is one of the most critical issues. This raises concerns about the risks associated with the booming tourism industry and migratory flows. In fact, even transient colonization with multidrug-resistant strains can present significant challenges to individual, family, and public health. Understanding the epidemiology and mechanisms of resistance, associated risk factors and prevention policies is therefore essential to ensure that strategies are in place to limit the global spread of high-risk bacterial clones and thereby protect public health.

Multiple displacement amplification (MDA) outperforms conventional PCR in long fragment and whole-genome amplification, making it attractive to couple MDA with long-read sequencing of samples with limited quantities of DNA to obtain improved genome assemblies. Here, we explore the efficacy and limits of MDA for efficient low-cost genome sequence assembly using Oxford Nanopore Technologies (ONTs) rapid library preparations and minION sequencing. We successfully generated almost complete genome sequences for all organisms examined, including Gram-positive (Staphylococcus aureus, Enterococcus faecium) and Gram-negative (Escherichia coli) prokaryotes and one challenging eukaryotic pathogen (Cryptosporidium spp) representing a broad spectrum of critical infectious disease pathogens. High-quality data from those samples were generated starting with only 0.025 ng of total DNA. Controlled sheared DNA samples exhibited a distinct pattern of size increase after MDA, which may be associated with the amplification of long, low-abundance fragments present in the assay, as well as generating concatemeric sequences during amplification. To address concatemers, we developed a computational pipeline (CADECT: Concatemer Detection Tool) to identify and remove putative concatemeric sequences. This study highlights the efficacy of MDA in generating high-quality genome assemblies from limited amounts of input DNA. Also, the CADECT pipeline effectively mitigated the impact of concatemeric sequences, enabling the assembly of contiguous sequences even in cases where the input genomic DNA was degraded. These results have significant implications for the study of organisms that are challenging to culture in vitro, such as Cryptosporidium, and for expediting critical results in clinical settings with limited quantities of available genomic DNA., (© 2025 The Author(s). Molecular Ecology Resources published by John Wiley & Sons Ltd.)

Sequencing DNA directly from patient samples enables faster pathogen characterization compared to traditional culture-based approaches, but often yields insufficient sequence data for effective downstream analysis. CRISPR-Cas9 enrichment is designed to improve the yield of low abundance sequences but has not been thoroughly explored with Oxford Nanopore Technologies (ONT) for use in clinical bacterial epidemiology. We designed CRISPR-Cas9 guide RNAs to enrich the human pathogen Klebsiella pneumoniae , by targeting multi-locus sequence type (MLST) and transfer RNA (tRNA) genes, as well as common antimicrobial resistance (AMR) genes and the resistance-associated integron gene intI1 . We validated enrichment performance in 20 K . pneumoniae isolates, finding that guides generated successful enrichment across all conserved sites except for one AMR gene in two isolates. Enrichment of MLST genes led to a correct allele call in all seven loci for 8 out of 10 isolates that had depth of 30× or more in these regions. We then compared enriched and unenriched sequencing of three human fecal samples spiked with K. pneumoniae at varying abundance. Enriched sequencing generated 56× and 11.3× the number of AMR and MLST reads, respectively, compared to unenriched sequencing, and required approximately one-third of the computational storage space. Targeting the intI1 gene often led to detection of 10-20 proximal resistance genes due to the long reads produced by ONT sequencing. We demonstrated that CRISPR-Cas9 enrichment combined with ONT sequencing enabled improved genomic characterization outcomes over unenriched sequencing of patient samples. This method could be used to inform infection control strategies by identifying patients colonized with high-risk strains., Importance: Understanding bacteria in complex samples can be challenging due to their low abundance, which often results in insufficient data for analysis. To improve the detection of harmful bacteria, we implemented a technique aimed at increasing the amount of data from target pathogens when combined with modern DNA sequencing technologies. Our technique uses CRISPR-Cas9 to target specific gene sequences in the bacterial pathogen Klebsiella pneumoniae and improve recovery from human stool samples. We found our enrichment method to significantly outperform traditional methods, generating far more data originating from our target genes. Additionally, we developed new computational techniques to further enhance the analysis, providing a thorough method for characterizing pathogens from complex biological samples., Competing Interests: The authors declare no conflict of interest.

Carbapenemase OXA-48 and its variants pose a serious threat to the development of effective treatments for bacterial infections. OXA-48-producing Enterobacterales are the most prevalent carbapenemase-producing bacteria in large parts of the world. Although these bacteria exhibit low-level carbapenem resistance in vitro , the infections they cause are challenging to treat with conventional therapies, owing to their spread and complex detection in clinical settings. However, numerous β-lactamase inhibitors (BLIs) are currently in the pipeline or late clinical stages. To assess the potential of these compounds, this study compared the efficacy against OXA-48 of novel β-lactamase inhibitors, specifically the 1,6-diazabicyclo[3,2,1]octanes (DBOs) avibactam, relebactam, zidebactam, nacubactam, and durlobactam, along with the cyclic and bicyclic boronates vaborbactam, taniborbactam, and xeruborbactam. The extensive kinetics assays identified xeruborbactam, taniborbactam, and durlobactam, together with the already established avibactam, as BLIs with superior biochemical performance. Susceptibility testing further validated these findings but also demonstrated significantly improved bacterial killing by the DBOs zidebactam, nacubactam, and durlobactam. On the other hand, binding studies demonstrated the superior inhibitory capacity of the BLIs durlobactam and xeruborbactam. Combinations, such as cefepime/zidebactam, meropenem/nacubactam, and sulbactam/durlobactam, show promising activity against OXA-48-producing Enterobacterales, while ceftazidime/avibactam, cefepime/taniborbactam, and meropenem/xeruborbactam combinations also appear highly active, largely due to the excellent kinetics of these new inhibitors. Overall, this comprehensive analysis provides important insights into the effectiveness of new BLIs against OXA-48-producing Enterobacterales, highlighting xeruborbactam, durlobactam, and avibactam as leading candidates. Additionally, BLIs like zidebactam, nacubactam, and taniborbactam also showed potential in addressing the clinical challenges posed by OXA-48-mediated antimicrobial resistance., Competing Interests: The authors declare no conflict of interest.

Objectives: To evaluate the in vitro susceptibility of ESBL-producing Enterobacterales isolates to ceftolozane/tazobactam (C/T), a combination of tazobactam (a ß-lactamase inhibitor) and a new antipseudomonal cephalosporin., Methods: From 2016 to 2019, susceptibilities of 10,545 Enterobacterales isolated from intra-abdominal, urinary tract, respiratory tract and bloodstream infections to C/T and 11 other antimicrobial agents were analyzed. Non-ESBL-producing isolates were included for comparative analysis to provide a comprehensive susceptibility profile., Results: Among 10,545 isolated Enterobacterales, 54.6% were ESBL producers. The ESBL-positive rates for E. coli (984/10,545, 47.3%) and K. pneumoniae (3,606/10,545, 34.2%) were 59.8% and 51.1%, respectively. The susceptibility rate to C/T for all Enterobacterales was 79.5%. For E. coli and K. pneumoniae, the C/T susceptibilities were 89.3% and 68.0%, respectively. For non-ESBL-producing Enterobacterales, susceptibility to C/T was 99.5%. The susceptibility of non-carbapenem-resistant (CR) ESBL-producing Enterobacterales to C/T was 81.0%. The isolation rates of ESBL-positive and carbapenem-resistant Enterobacterales (CRE), CR-E. coli, and CR-K. pneumoniae were 14.3%, 5.6% and 26.8%, respectively. The susceptibility of ESBL-positive CREs to C/T was < 20% for most antimicrobials except amikacin (50.4%). The susceptibility of ESBL-positive CR-E. coli to C/T was 28.2. For ESBL-producing CR-K. pneumoniae, susceptibility to most antimicrobials was < 10%, except for amikacin (37.4%)., Conclusions: The present research underscores the viability of C/T as an alternative to carbapenems for the treatment of ESBL-producing, carbapenem susceptible Enterobacterales. However, the susceptibilities of ESBL-positive CRE to C/T and other studied antimicrobials were consistently below 20%, emphasizing for new innovative treatment strategies., Competing Interests: Declaration of competing interest Yue Kang is an employee of MSD China. All other authors declare no competing interests., (Copyright © 2025. Published by Elsevier Ltd.)

Introduction. Carbapenems are usually employed as first-line antimicrobials against bacteria harbouring extended-spectrum beta-lactamases (ESBLs). These enzymes confer resistance often to multiple classes of antimicrobials. Hypothesis/Gap Statement. This indiscriminate use of carbapenems and the inevitable development of carbapenem resistance have prompted the need for carbapenem-sparing strategies. Methodology. The non-carbapenem antimicrobial susceptibility patterns of 60 ESBL-producing Enterobacterales (ESBL-PE) isolates responsible for bloodstream infections, in 2022-2023 inclusive, processed at our institution were reviewed. Results. The non-carbapenem antimicrobial susceptibility patterns of 60 ESBL-PE isolates from bloodstream infections during the study period were determined. Escherichia coli was the most common species isolated (87%, n =52), with the majority of cases (73.3%, n =44) originating from a presumed urinary source. Temocillin (TMC), mecillinam (MEC), cefiderocol (FDC), amikacin and fosfomycin (FOS) displayed excellent activity against all ESBL-PE isolates tested, with susceptibility rates of≥85%. Ciprofloxacin and amoxicillin-clavulanic acid were the least efficacious agents, with susceptibility rates≤20%. Conclusions. TMC, MEC, FDC and FOS offer promising alternatives to carbapenems, demonstrating efficacy against ESBL-PE. The use of these agents not only broadens the therapeutic arsenal against ESBL-PE but also mitigates the potential for escalating carbapenem resistance, especially in regions where the incidence of carbapenem resistance is increasing.

Carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) represent a significant global threat. The emergence of dual CP-CRE is particularly alarming, as they can potentially compromise the efficacy of newer antibiotics, further decreasing therapeutic alternatives. Herein, we report the emergence of multiple species of CP-CRE recovered from invasive infections in Chile that simultaneously harbor bla KPC and provide an in-depth genomic characterization of these worrisome pathogens. We collected carbapenem-resistant Enterobacterales (CRE) isolates from invasive infections over a 4-year period, across 11 healthcare centers in Chile. Bacterial species and the presence of carbapenemase genes were confirmed using MALDI-TOF and PCR assays, respectively. Antimicrobial susceptibility testing was conducted through disk diffusion and broth microdilution methods. Dual CP-CRE isolates were subjected to short- and long-read whole genome sequencing to perform a detailed genomic characterization of the isolates and of the mobile genetic elements harboring the enzymes. From a total of 1,335 CRE isolates, we observed an increase in the prevalence of CP-CRE, from 11% in 2019 to 38% in 2022. A total of 11 dual CP-CRE isolates were recovered, all of them harboring bla NDM and provide an in-depth genomic characterization of these worrisome pathogens. We collected carbapenem-resistant Enterobacterales (CRE) isolates from invasive infections over a 4-year period, across 11 healthcare centers in Chile. Bacterial species and the presence of carbapenemase genes were confirmed using MALDI-TOF and PCR assays, respectively. Antimicrobial susceptibility testing was conducted through disk diffusion and broth microdilution methods. Dual CP-CRE isolates were subjected to short- and long-read whole genome sequencing to perform a detailed genomic characterization of the isolates and of the mobile genetic elements harboring the enzymes. From a total of 1,335 CRE isolates, we observed an increase in the prevalence of CP-CRE, from 11% in 2019 to 38% in 2022. A total of 11 dual CP-CRE isolates were recovered, all of them harboring bla KPC and bla NDM . Species corresponded to Escherichia coli ( n = 6), Klebsiella pneumoniae ( n = 2), Klebsiella oxytoca ( n = 2), and Citrobacter freundii ( n = 1). Dual CP-CRE isolates exhibited resistance to all tested β-lactams except for cefiderocol. The bla KPC and bla NDM encoding genes were located on independent plasmids. Platforms harboring bla KPC were diverse and included IncN, IncF, and IncFIB plasmids. In contrast, bla NDM-7 was only found on fairly conserved IncX3 plasmids. We report that a rapid increase of CP-CRE in Chile, alongside with the emergence of multiple bacterial species of CP-CRE co-harboring bla KPC-2/3 and bla NDM-7 , underscores a critical public health challenge. Our data suggest that the dissemination of bla NDM-7 was predominantly facilitated by IncX3 plasmids, whereas the spread of bla KPC involved multiple plasmid backbones. Active surveillance and genomic monitoring are critical to inform public policy and curtail the spread of these highly resistant pathogens., Competing Interests: The authors declare no conflict of interest.

The increasing prevalence of infections due to metallo-β-lactamase (MBL)-producing Enterobacterales poses a serious concern given the limited treatment options available. This systematic literature review (SLR) describes the molecular epidemiology, geographical distribution, and clinical outcomes of such infections. Systematic searches of literature published between January 2013 and May 2023 were performed, and 39 studies with an MBL sample size of ≥25 isolates and ≥2 well-defined outcomes were eligible. Most of the studies were from Asia (21/39) followed by Europe (11/39) and evaluated more than two species (24/39). Overall, the percentage of MBL-producing isolates ranged from 6.8%-100.0%. Among 6620 MBL-producers, the majority were from Europe (3837/6620; 58.0%), followed by Asia (2079/6620; 31.4%). New Delhi MBL (NDM)-producers (5668/6620; 85.6%) were the most frequent across all regions, with NDM-1 as the common variant. The majority of IMP-producing isolates (586/592; 99.0%) came from Asia, while the majority of VIM-producing isolates were found in Europe (322/371; 86.8%). Studies focused on MBL-specific outcomes (n = 28) reported reduced susceptibility (<80.0%) to most antimicrobials except for colistin and tigecycline. Six studies reported significantly longer hospital and/or ICU stay due to MBL-Enterobacterales compared to other infection groups. Common mortality measures reported were overall mortality (18.8%-57.0%; 9 studies), in-hospital mortality (11.1%-55.3%; 6 studies), and 30-day mortality (0%-36.4%; 7 studies). Previous antibiotic use (9 studies) and hospital and/or ICU stay (8 studies) were common risk factors for colonization/infection and mortality. Reporting of MBL prevalence across regions will provide a better understanding of the infection burden and prevent further spread., (Copyright © 2025 Pfizer Inc., USA. Published by Elsevier Ltd.. All rights reserved.)

Introduction. Genes encoding OXA-48-like carbapenem-hydrolyzing enzymes are often located on plasmids and are abundant among carbapenemase-producing Enterobacterales (CPE) worldwide. After a large bla OXA-48 plasmid-mediated outbreak in 2011, routine screening of patients at risk of CPE carriage on admission and every 7 days during hospitalization was implemented in a large hospital in the Netherlands. The objective of this study was to investigate the dynamics of the hospitals' 2011 outbreak-associated bla OXA-48 plasmid among CPE collected from 2011 to 2021. Methods. A selection of 86 bla OXA-48 -carrying CPE isolates was made from 374 isolates collected over an 11-year study period. Species included Escherichia coli (Eco), Klebsiella pneumoniae (Kpn), Enterobacter cloacae complex (Ecl), Citrobacter freundii (Cfr), Citrobacter koseri (Cko) and Morganella morgani (Mmo). Short-read sequencing was combined with long-read sequencing for all isolates to reconstruct bla OXA-48 -like plasmids and chromosomes of CPE. MASH, MOBsuite, ResFinder, PlasmidFinder and SNP analyses were performed to study diversity. pOXA-48 plasmids were compared to plasmid sequences that were sequenced for the Dutch CPE surveillance in the same time period. Results. In total for the 86 CPE, 2 failed genomic assemblies and 78 bla OXA-48 -encoding plasmids were reconstructed, and six bla OXA-48 genes were located chromosomally. The 2011 outbreak-associated bla OXA-48 plasmid of 63.6 kb with IncL replicon was found in Cfr, Ecl, Eco, Kpn and Mmo and primarily between 2011 and 2014 and indicated as LR025105 as MASH nearest neighbour. From 2014 onwards, 11 other types of bla OXA-48 -carrying plasmids with different antibiotic-resistant genes and replicons were discovered, representing the earlier defined distinct pOXA-48 plasmid groups found in the Netherlands. Furthermore, on a national level, the LR025105 plasmid was found after 2015 in many different bacterial backgrounds, highlighting the promiscuous nature of this pOXA-48 plasmid. Conclusion. After a large bla OXA-48 outbreak in a large hospital in the Netherlands, the composition of the bla OXA-48 plasmid population in this hospital diversified over time and is in line with national surveillance data. Plasmid sequencing provided valuable insight into the transmission dynamics of bla OXA-48 -encoding plasmids and showed no indication of the persistence of the 2011 bla OXA-48 plasmid in the hospital environment.