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Despite national guidelines that recommend shorter durations of antibiotic therapy for children with uncomplicated acute otitis media, 75% of a cohort of children from two large academic health centers received long-duration prescriptions.

Next-generation sequencing (NGS)-based assays are primarily available from reference laboratories for diagnostic use. These tests can provide helpful diagnostic data but also can be overused by ordering providers not fully understanding their limitations. At present, there are few best practice guidelines for use. NGS-based assays can carry a high cost to institutions and individual patients, requiring thoughtful use through application of diagnostic stewardship principles. This article provides an overview of diagnostic stewardship approaches as applied to these assays, focusing on principles of collaboration, differential diagnosis formation, and seeking the best patient, syndrome, sample, timing, and test for improved patient care.

It has been proposed that the use of the BioFire FilmArray Pneumonia Panel may improve appropriate antibiotic use for pneumonia. We evaluated real-world use of the test in children and found limited impact on antibiotic use.

AbstractObjective:To improve appropriate antibiotic prescribing for children in Tennessee.Design:We performed a before-and-after intervention study with 3 comparison periods: period 1 (P1, baseline) May 2018–September 2019; period 2 (P2, intervention before the COVID-19 pandemic) November 11, 2019–March 20, 2020; and period 3 (P3, intervention during the coronavirus disease 2019 [COVID-19] pandemic) March 21, 2020–November 10, 2020. We additionally surveyed participating providers to assess acceptance of the intervention.Setting:Community general pediatrics practices.Participants:In total, 81 general pediatricians, family medicine physicians, and nurse practitioners in 5 general pediatrics practices participated in this study.Interventions:Each practice identified a practice and operations champion for the project. Practices chose 2–4 implementation strategies previously shown to be effective at reducing outpatient antibiotic use to implement in their practice throughout the study intervention period. Study personnel also held quarterly meetings with all providers to review deidentified peer comparison feedback both across practices enrolled in the study and at the provider level within each practice.Results:We detected improvements in guideline-concordant antibiotic use in the pre-COVID-19 intervention period, and they were sustained in the study period during the pandemic (P3): otitis media (P1 72.14% vs P2 81.42% vs P3 86.11%), group A streptococcal pharyngitis (P1 66.13% vs P2 81.56% vs P3 80.44%), pneumonia (P1 70.6% vs P2 76.2% vs P3 100%), sinusitis (P1 76.2% vs P2 83.78% vs P3 82.86%), skin and soft-tissue infections (P1 97.18% vs P2 100% vs P3 100%).Conclusions:Bundled implementation strategies led to significant increases in guideline-concordant antibiotic prescribing for all diagnoses. Survey results demonstrate that the bundled implementation strategies were well-accepted by providers.

We conducted a national survey of pediatric infectious diseases (ID) clinicians on outpatient parenteral antibiotic therapy (OPAT) practices and post-discharge ID follow-up. Only 15% of sites required ID consultation for all OPAT. ID division resources for post-discharge care varied. Opportunities exist to increase ID involvement in post-discharge management of serious infections.A national survey of pediatric infectious diseases clinicians on outpatient parenteral antibiotic therapy practices found only 15% of sites required ID consultation for all OPAT. Resources for post-discharge care varied. Opportunities exist to increase ID involvement in post-discharge management of serious infections.

AbstractAntibiotics are widely used in neonatal intensive care units (NICUs). We conducted a cross-sectional analysis of antibiotic use across US NICUs to evaluate overall, broad-spectrum, and combination antibiotic use. Patterns of antibiotic use varied by medical versus surgical service line, hospital, and geographic location.

AbstractWe surveyed pediatric antimicrobial stewardship program (ASP) site leaders within the Sharing Antimicrobial Reports for Pediatric Stewardship collaborative regarding discharge stewardship practices. Among 67 sites, 13 (19%) reported ASP review of discharge antimicrobial prescriptions. These findings highlight discharge stewardship as a potential opportunity for improvement during the hospital-to-home transition.

Antibiotic use is common in the neonatal intensive care unit. The density and heterogeneity of antibiotic prescribing suggests inappropriate and overuse of these agents. Potential antibiotic stewardship targets include sepsis, necrotizing enterocolitis, and perioperative prophylaxis. Diagnostic stewardship principles, including appropriately obtained cultures, may be leveraged to decrease unnecessary antibiotic prescribing. Strategies including guideline development, prospective audit and feedback, and formulary restriction have been successfully deployed in the neonatal intensive care unit to improve the quality of antibiotic prescribing. Implementation of antibiotic stewardship in the neonatal intensive care unit requires multidisciplinary collaboration between neonatologists, surgeons, infectious diseases specialists, pharmacists, and nurses.

Introduction: The kinetics of procalcitonin in pediatric patients with non-critical acute bacterial infections receiving appropriate antibiotic therapy are not well described. Methods: We performed a single-center, prospective observational pilot study of children admitted to a tertiary care children’s hospital who were receiving antibiotics for treatment of a non-critical acute bacterial infection, and we prospectively measured serial procalcitonin levels daily for 4 days during hospitalization. Results: Among the 46 children with baseline procalcitonin levels enrolled in the study, procalcitonin kinetics followed a half-life of approximately 24 h in most patients. Procalcitonin declined faster than C-reactive protein over the first 48 h of appropriate antibiotic treatment. There was variation in biomarker levels among participants with the same infection type, especially in participants with bacteremia, musculoskeletal infection and skin/soft tissue infection. Conclusion: Utility of procalcitonin as a biomarker to follow every 24–48 h in non-critically ill children receiving antibiotic therapy for bacterial infections as an objective measure of clinical improvement is promising.

AbstractObjective:To quantify the impact of clinical guidance and rapid respiratory and meningitis/encephalitis multiplex polymerase chain reaction (mPCR) testing on the management of infants.Design:Before-and-after intervention study.Setting:Tertiary-care children’s hospital.Patients:Infants ≤90 days old presenting with fever or hypothermia to the emergency department (ED).Methods:The study spanned 3 periods: period 1, January 1, 2011, through December 31, 2014; period 2, January 1, 2015, through April 30, 2018; and period 3, May 1, 2018, through June 15, 2019. During period 1, no standardized clinical guideline had been established and no rapid pathogen testing was available. During period 2, a clinical guideline was implemented, but no rapid testing was available. During period 3, a guideline was in effect, plus mPCR testing using the BioFire FilmArray respiratory panel 2 (RP 2) and the meningitis encephalitis panel (MEP). Outcomes included antimicrobial and ancillary test utilization, length of stay (LOS), admission rate, 30-day mortality. Outcomes were compared across periods using Kruskal-Wallis and Pearson tests and interrupted time series analysis.Results:Overall 5,317 patients were included: 2,514 in period 1, 2,082 in period 2, and 721 in period 3. Over the entire study period, we detected reductions in the use of chest radiographs, lumbar punctures, LOS, and median antibiotic duration. After adjusting for temporal trends, we observed that the introduction of the guideline was associated with reductions in ancillary tests and lumbar punctures. Use of mPCR testing with the febrile infant clinical guideline was associated with additional reductions in ancillary testing for all patients and a higher proportion of infants 29–60 days old being managed without antibiotics.Conclusions:Use of mPCR testing plus a guideline for young infant evaluation in the emergency department was associated with less antimicrobial and ancillary test utilization compared to the use of a guideline alone.

AbstractObjective:To characterize the prevalence of and seasonal and regional variation in inpatient antibiotic use among hospitalized US children in 2017–2018.Design:We conducted a cross-sectional examination of hospitalized children. The assessments were conducted on a single day in spring (May 3, 2017), summer (August 2, 2017), fall (October 25, 2017), and winter (January 31, 2018). The main outcome of interest was receipt of an antibiotic on the study day.Setting:The study included 51 freestanding US children’s hospitals that participate in the Pediatric Health Information System (PHIS).Patients:This study included all patients <18 years old who were admitted to a participating PHIS hospital, excluding patients who were admitted solely for research purposes.Results:Of 52,769 total hospitalized children, 19,174 (36.3%) received antibiotics on the study day and 6,575 of these (12.5%) received broad-spectrum antibiotics. The overall prevalence of antibiotic use varied across hospitals from 22.3% to 51.9%. Antibiotic use prevalence was 29.2% among medical patients and 47.7% among surgical patients. Although there was no significant seasonal variation in antibiotic use prevalence, regional prevalence varied, ranging from 32.7% in the Midwest to 40.2% in the West (P< .001). Among units, pediatric intensive care unit patients had the highest prevalence of both overall and broad-spectrum antibiotic use at 58.3% and 26.6%, respectively (P< .001).Conclusions:On any given day in a national network of children’s hospitals, more than one-third of hospitalized children received an antibiotic, and 1 in 8 received a broad-spectrum antibiotic. Variation across hospitals, setting and regions identifies potential opportunities for enhanced antibiotic stewardship activities.

AbstractObjective:To identify patient and provider characteristics associated with high-volume antibiotic prescribing for children in Tennessee, a state with high antibiotic utilization.Design:Cross-sectional, retrospective analysis of pediatric (aged <20 years) outpatient antibiotic prescriptions in Tennessee using the 2016 IQVIA Xponent (formerly QuintilesIMS) database.Methods:Patient and provider characteristics, including county of prescription fill, rural versus urban county classification, patient age group, provider type (nurse practitioner, physician assistant, physician, or dentist), physician specialty, and physician years of practice were analyzed.Results:Tennessee providers wrote 1,940,011 pediatric outpatient antibiotic prescriptions yielding an antibiotic prescribing rate of 1,165 per 1,000 population, 50% higher than the national pediatric antibiotic prescribing rate. Mean antibiotic prescribing rates varied greatly by county (range, 39–2,482 prescriptions per 1,000 population). Physicians wrote the greatest number of antibiotic prescriptions (1,043,030 prescriptions, 54%) of which 56% were written by general pediatricians. Pediatricians graduating from medical school prior to 2000 were significantly more likely than those graduating after 2000 to be high antibiotic prescribers. Overall, 360 providers (1.7% of the 21,798 total providers in this dataset) were responsible for nearly 25% of both overall and broad-spectrum antibiotic prescriptions; 20% of these providers practiced in a single county.Conclusions:Fewer than 2% of providers account for 25% of pediatric antibiotic prescriptions. High antibiotic prescribing for children in Tennessee is associated with specific patient and provider characteristics that can be used to design stewardship interventions targeted to the highest prescribing providers in specific counties and specialties.

Agreement between available procalcitonin (PCT) assays is unclear. We sought to compare concordance between Roche and bioMérieux PCT assays using pediatric samples. We evaluated 213 plasma samples from 208 children. We tested each sample on both the Roche and bioMérieux PCT platforms. At ranges < 2 μg/L, the Roche platform had a mean negative bias of 0.13 μg/L versus the bioMérieux platform. This bias resulted in PCT levels that crossed accepted cut points in 12.7% of patients. PCT levels measured on either platform are similar, especially at PCT ranges used for antibiotic decision-making algorithms. This work was supported by an investigator-initiated research agreement through bioMérieux and by the National Institute of Allergy and Infectious Diseases Childhood Infection Research Program (ChIRP), National Institute of Health and the National Center for Advancing Translational Sciences of the National Institute of Health.

Recent studies in adults have found an incidence of acute kidney injury (AKI) in patients treated with a combination of vancomycin and piperacillin-tazobactam (TZP) that is greater than that expected with either medication alone. The purpose of this study was to determine whether combination therapy with vancomycin and TZP is associated with an incidence of AKI in pediatric patients higher than that in those on combination therapy with vancomycin and cefepime.

AbstractWe observed pediatric S. aureushospitalizations decreased 36% from 26.3 to 16.8 infections per 1,000 admissions from 2009 to 2016, with methicillin-resistant S. aureus(MRSA) decreasing by 52% and methicillin-susceptible S. aureusdecreasing by 17%, among 39 pediatric hospitals. Similar decreases were observed for days of therapy of anti-MRSA antibiotics.

Prolonged antibiotic administration has been associated with peripheral cytopenias in up to 10-15% of patients. Of these, neutropenia is particularly notable because of the associated risk of severe bacterial infections. Yet, the mechanisms underlying antibiotic-associated neutropenia remain poorly understood. Recent studies in murine models demonstrate that antibiotics suppress hematopoiesis by depletion of the intestinal microbiota, with concomitant suppression of basal Type I interferon (IFN) and STAT1 signaling. Oral administration of the microbial metabolites that induce Type I IFN restores normal hematopoiesis in antibiotic-treated mice. These findings support a paradigm in which products of the intestinal microbiota enter the bloodstream and travel to the bone marrow where they promote production of growth cytokines that support normal hematopoiesis.

The prevalence of pediatric antimicrobial stewardship programs (ASPs) is increasing in acute care facilities across the United States. Over the past several years, the evidence base used to inform effective stewardship practices has expanded, and regulatory interest in stewardship programs has increased. Here, we review approaches for established, hospital-based pediatric ASPs to adapt and report standardized metrics, broaden their reach to specialized populations, expand to undertake novel stewardship initiatives, and implement rapid diagnostics to continue their evolution in improving antimicrobial use and patient outcomes.

The U.S. Centers for Disease Control and Prevention (CDC) funds five Regional Tuberculosis Training and Medical Consultation Centers (RTMCCs) that provide training and consultation for tuberculosis (TB) control and management. RTMCC utilization for assistance with diagnosis and management of TB in children has not been described. We analyzed pediatric TB consultations performed across all RTMCCs in terms of question type, provider type, and setting.

The recent increase in multidrug-resistant (MDR) Escherichia coliinfections is not well described in children. We determined the risk factors and outcomes of extraintestinal E. coliinfections in children in our region. We conducted a retrospective cohort study of children ≤18 years in Olmsted County, MN, USA, between January 1, 2012 and December 31, 2012. MDR isolates were defined as resistant to ≥3 antibiotic classes. A total of 368 children each contributed 1 isolate. Isolates were predominantly community-associated (82%) and from urine (90%), and outpatients (86%); 46 (13%) isolates were MDR. In multivariable analysis, genitourinary (GU) tract anomaly (OR 2.42, 95% CI 1.03–5.68), invasive devices (OR 3.48, 95% CI 1.37–8.83) and antibiotic use at presentation (OR 2.62, 95% CI 1.06–6.47) were associated with MDR E. coli. Children with MDR infections were more likely to have a complex infection (35% vs. 17%, P= 0.026), less likely to receive effective empiric antibiotics (47% vs. 74%, P< 0.001), had longer time to receipt of effective antibiotics (median 19.2 vs. 0.6 h, P< 0.001), and longer hospitalization (median 10 vs. 4 days, P= 0.029) than children with non-MDR infections. Pediatric MDR E. coliinfection was associated with GU tract anomaly, invasive devices, antibiotic use, delays in effective therapy and longer hospitalization.

ABSTRACTCarbapenem resistance among the Enterobacteriaceae has become a significant clinical and public health dilemma. Rapid administration of effective antimicrobials and implementation of supplemental infection control practices is required to both improve patient outcomes and limit the spread of these highly resistant organisms. However, carbapenem-resistant Enterobacteriaceae (CRE)-infected patients are predominantly identified by routine culture methods, which take days to perform. Rapid genomic and phenotypic methods are currently available to accelerate the identification of carbapenemase-producing CRE. Effective use of these technologies is reliant on close collaboration between clinical microbiology, infection prevention, antimicrobial stewardship and infectious diseases specialists. This review discusses the performance characteristics of these technologies to date, and describes strategies for their optimal implementation.

There are striking similarities between the dual pandemics of multidrug-resistant tuberculosis (MDR TB) and multidrug-resistant Gram negative bacilli (MDR GNB) despite fundamental differences in the pathogenesis and epidemiology of these pathogens. In this perspective, we highlight several strategies that have been used by the global TB community to address the MDR TB problem, including approaches to: encourage appropriate use of anti-TB medications, enhance appropriate utilization of molecular diagnostic testing, facilitate development of new antimicrobial agents, and strengthen surveillance systems and infection control practices. Understanding the successes and challenges of these strategies for MDR TB control will be instructive for efforts to curb emergence and spread of MDR GNB.

ABSTRACTWe describe a 16-year-old neutropenic patient from the Middle East with bloodstream infection caused by two carbapenemase-producing Escherichia coliisolates that we characterized by whole-genome sequencing. While one displayed meropenem resistance and was blaNDMpositive, the other demonstrated meropenem susceptibility yet harbored blaOXA181(which encodes a blaOXA48-like enzyme). This report highlights the challenge of laboratory detection of blaOXA48-like enzymes and the clinical implications of genotypic resistance detection in carbapenemase-producing Enterobacteriaceae.

ObjectiveTo identify current outpatient parenteral antibiotic therapy practice patterns and complications.MethodsWe administered an 11-question survey to adult infectious disease physicians participating in the Emerging Infections Network (EIN), a Centers for Disease Control and Prevention–sponsored sentinel event surveillance network in North America. The survey was distributed electronically or via facsimile in November and December 2012. Respondent demographic characteristics were obtained from EIN enrollment data.ResultsOverall, 555 (44.6%) of EIN members responded to the survey, with 450 (81%) indicating that they treated 1 or more patients with outpatient parenteral antimicrobial therapy (OPAT) during an average month. Infectious diseases consultation was reported to be required for a patient to be discharged with OPAT by 99 respondents (22%). Inpatient (282 [63%] of 449) and outpatient (232 [52%] of 449) infectious diseases physicians were frequently identified as being responsible for monitoring laboratory results. Only 26% (118 of 448) had dedicated OPAT teams at their clinical site. Few infectious diseases physicians have systems to track errors, adverse events, or “near misses” associated with OPAT (97 [22%] of 449). OPAT-associated complications were perceived to be rare. Among respondents, 80% reported line occlusion or clotting as the most common complication (occurring in 6% of patients or more), followed by nephrotoxicity and rash (each reported by 61%). Weekly laboratory monitoring of patients who received vancomycin was reported by 77% of respondents (343 of 445), whereas 19% of respondents (84 of 445) reported twice weekly laboratory monitoring for these patients.ConclusionsAlthough use of OPAT is common, there is significant variation in practice patterns. More uniform OPAT practices may enhance patient safety.

ABSTRACTEscherichia colisequence type 131 (ST131) is an extensively antimicrobial-resistant E. coliclonal group that has spread explosively throughout the world. Recent molecular epidemiologic and whole-genome phylogenetic studies have elucidated the fine clonal structure of ST131, which comprises multiple ST131 subclones with distinctive resistance profiles, including the (nested) H30, H30-R, and H30-Rx subclones. The most prevalent ST131 subclone, H30, arose from a single common fluoroquinolone (FQ)-susceptible ancestor containing allele 30 of fimH(type 1 fimbrial adhesin gene). An early H30 subclone member acquired FQ resistance and launched the rapid expansion of the resulting FQ-resistant subclone, H30-R. Subsequently, a member of H30-R acquired the CTX-M-15 extended-spectrum beta-lactamase and launched the rapid expansion of the CTX-M-15-containing subclone within H30-R, H30-Rx. Clonal expansion clearly is now the dominant mechanism for the rising prevalence of both FQ resistance and CTX-M-15 production in ST131 and in E. coligenerally. Reasons for the successful dissemination and expansion of the key ST131 subclones remain undefined but may include increased transmissibility, greater ability to colonize and/or persist in the intestine or urinary tract, enhanced virulence, and more-extensive antimicrobial resistance compared to other E. coli. Here we discuss the epidemiology and molecular phylogeny of ST131 and its key subclones, possible mechanisms for their ecological success, implications of their widespread dissemination, and future research needs.

Rectal colonization with multidrug-resistant Enterobacteriaceae was found in 23 of 94 consecutively enrolled international patients hospitalized at Mayo Clinic, Rochester, Minnesota. No carbapenemase producers were detected. Twenty-one isolates were extended-spectrum β-lactamase-producing Escherichia coli.Colonization was associated with gastrointestinal disease and central venous catheter placement within the antecedent year.

ABSTRACTWe assessed Escherichia coliST131 and its H30 and H30-Rx subclones for virulence genes, antimicrobial resistance, and extended-spectrum beta-lactamase (ESBL) type. Although both subclones were associated with ESBL production, H30-Rx isolates had higher resistance scores and were associated specifically with CTX-M-15. Three virulence genes (iha, sat, and iutA) were more prevalent among H30 than non-H30 ST131 isolates. Thus, the H30 and H30-Rx subclones are more antimicrobial resistant and have virulence profiles that are distinct from those of non-H30 ST131 isolates.

ABSTRACTThe clonal distribution of Escherichia coliacross an unselected population in the current era of widespread antimicrobial resistance is incompletely defined. In this study, we used a newly described clonal typing strategy based on sequencing of fumCand fimH(i.e., CH typing) to infer multilocus sequence types (STs) for 299 consecutive, nonduplicate extraintestinal E. coliisolates from all cultures submitted to Olmsted County, MN, laboratories in February and March 2011 and then compared STs with epidemiological data. Forty-seven different STs were identified, most commonly ST131 (27%), ST95 (11%), ST73 (8%), ST127 (6%), and ST69 (5%). Isolates from these five STs comprised two-thirds of health care-associated (HA) isolates but only half of community-associated (CA) isolates. ST131 was represented overwhelmingly (88%) by a single recently expanded H30 subclone, which was the most extensively antimicrobial-resistant subclone overall and was especially predominant in HA infections and among adults >50 years old. In contrast, among patients 11 to 50 years old, ST69, -95, and -73 were more common. Because of the preponderance of the H30 subclone of ST131, ST diversity was lower among HA than CA isolates, and among antimicrobial-resistant than antimicrobial-susceptible isolates, which otherwise had similar ST distributions. In conclusion, in this U.S. Midwest region, the distribution and diversity of STs among extraintestinal E. coliclinical isolates vary by patient age, type of infection, and resistance phenotype. ST131 predominates among young children and the elderly, HA infections, and antimicrobial-resistant isolates, whereas other well-known pathogenic lineages are more common among adolescents and young adults, CA infections, and antimicrobial-susceptible isolates.

Objective.To identify predictors of community-onset extended-spectrum ß-lactamase (ESBL)-producing Escherichia coliinfection.Design.Prospective case-control study.Setting.Acute care hospitals and ambulatory clinics in the Chicago, Illinois, region.Patients.Adults with E. coliclinical isolates cultured in ambulatory settings or within 48 hours of hospital admission.Methods.Cases were patients with ESBL-producing E. coliclinical isolates cultured in ambulatory settings or within 48 hours of admission, and controls were patients with non-ESBL-producing E. coliisolates, matched to cases by specimen, location, and date. Clinical variables were ascertained through interviews and medical record review. Molecular methods were used to identify ESBL types, sequence type ST131, and aac(6')-Ib-cr.Results.We enrolled 94 cases and 158 controls. Multivariate risk factors for ESBL-producing E. coliinfection included travel to India in the past year (odds ratio [OR], 14.40 [95% confidence interval (CI), 2.92-70.95]), ciprofloxacin use (OR, 3.92 [95% CI, 1.90-8.1]), and age (OR, 1.04 [95% CI, 1.02-1.06]). Case isolates exhibited high prevalence of CTX-M-15 (78%), ST131 (50%), and aac(6')-Ib-cr(66% of isolates with CTX-M-15).Conclusions.Providers should be aware of the increased risk of ESBL-producing E. coliinfection among returned travelers, especially those from India.

Use of outpatient parenteral antimicrobial therapy (OPAT) in pediatrics is widespread and may be increasing. Recent data quantifying use and characteristics of pediatric OPAT are lacking.

Objective.To determine prevalence, predictors, and outcomes of infection due to Escherichia colisequence type ST131.Design.Retrospective cohort.Setting.All healthcare settings in Olmsted County, Minnesota (eg, community hospital, tertiary care center, long-term care facilities, and ambulatory clinics).Patients.Ambulatory and hospitalized children and adults with extraintestinal E. coliisolates.Methods.We analyzed 299 consecutive, nonduplicate extraintestinal E. coliisolates submitted to Olmsted County laboratories in February and March 2011. ST131 was identified using single-nucleotide polymorphism polymerase chain reaction and further evaluated through pulsed-field gel electrophoresis. Associated clinical data were abstracted through medical record review.Results.Most isolates were from urine specimens (90%), outpatients (68%), and community-associated infections (61%). ST131 accounted for 27% of isolates overall and for a larger proportion of those isolates resistant to fluoroquinolones (81%), trimethoprim-sulfamethoxazole (42%), gentamicin (79%), and ceftriaxone (50%). The prevalence of ST131 increased with age (accounting for 5% of isolates from those 11–20 years of age, 26% of isolates from those 51–60 years of age, and 50% of isolates from those 91–100 years of age). ST131 accounted for a greater proportion of healthcare-associated isolates (49%) than community-associated isolates (15%) and for fully 76% of E. coliisolates from long-term care facility (LTCF) residents. Multivariable predictors of ST131 carriage included older age, LTCF residence, previous urinary tract infection, high-complexity infection, and previous use of fluoroquinolones, macrolides, and extended-spectrum cephalosporins. With multivariable adjustment, ST131-associated infection outcomes included receipt of more than 1 antibiotic (odds ratio [OR], 2.54 [95% confidence interval (CI), 1.25–5.17]) and persistent or recurrent symptoms (OR, 2.53 [95% CI, 1.08–5.96]). Two globally predominant ST131 pulsotypes accounted for 45% of STB 1 isolates.Conclusions.ST131isa dominant, antimicrobial-resistant clonal group associated with healthcare settings, elderly hosts, and persistent or recurrent symptoms.

A rapid increase in multidrug-resistant Gram-negative infections has led to a reemergence of colistin use globally. Although it is well described among adults, colistin use and its associated toxicities in children are poorly understood. We report findings from the largest case series of pediatric colistin use to date.

To better understand the epidemiology of drug-resistant Escherichia coliacross health care and community settings.

To better characterize Streptococcus pneumoniae-associated hemolytic-uremic syndrome (SP-HUS), we report the largest series of SP-HUS among children in North America.

Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to β-lactam antibiotics because it expresses penicillin-binding protein 2a (PBP2a), a low-affinity penicillin-binding protein. An investigational broad-spectrum cephalosporin, ceftobiprole (BPR), binds PBP2a with high affinity and is active against MRSA. We hypothesized that BPR resistance could be mediated by mutations in mecA, the gene encoding PBP2a. We selected BPR-resistant mutants by passage in high-volume broth cultures containing subinhibitory concentrations of BPR. We used strain COLnex (which lacks chromosomal mecA) transformed with pAW8 (a plasmid vector only), pYK20 (a plasmid carrying wild-type mecA), or pYK21 (a plasmid carrying a mutant mecA gene corresponding to five PBP2a mutations). All strains became resistant to BPR by day 9 of passaging, but MICs continued to increase until day 21. MICs increased 256-fold (from 1 to 256 µg/ml) for pAW8, 32-fold (from 4 to 128 µg/ml) for pYK20, and 8-fold (from 16 to 128 µg/ml) for pYK21. Strains carrying wild-type or mutant mecA developed six (pYK20 transformants) or four (pYK21 transformants) new mutations in mecA. The transformation of COLnex with a mecA mutant plasmid conferred BPR resistance, and the loss of mecA converted resistant strains into susceptible ones. Modeling studies predicted that several of the mecA mutations altered BPR binding; other mutations may have mediated resistance by influencing interactions with other proteins. Multiple mecA mutations were associated with BPR resistance in MRSA. BPR resistance also developed in the strain lacking mecA, suggesting a role for chromosomal genes.

Plasmepsin II, an aspartic protease from the human intraerythrocytic parasite Plasmodium falciparum, is involved in degradation of the host cell hemoglobin within the acidic food vacuole of the parasite. Previous characterization of enzymatic activities from Plasmodiumsoluble extracts, responsible for in vitrohydrolysis of erythrocyte spectrin, had shown that the hydrolysis process occurred at pH 5.0 and involved aspartic protease(s) cleaving mainly within the SH3 motif of the spectrin α-subunit. Therefore, we used a recombinant construct of the erythroid SH3 motif as substrate to investigate the involvement of plasmepsins in spectrin hydrolysis. Using specific anti-plasmepsin II antibodies in Western blotting experiments, plasmepsin II was detected in chromatographic fractions enriched in the parasite SH3 hydrolase activity. Involvement of plasmepsin II in hydrolysis was demonstrated by mass spectrometry identification of cleavage sites in the SH3 motif, upon hydrolysis by Plasmodiumextract enzymatic activity, and by recombinant plasmepsin II. Furthermore, recombinant plasmepsin II digested native spectrin at pH 6.8, either purified or situated in erythrocyte ghosts. Additional degradation of actin and protein 4.1 from ghosts was observed. Specific antibodies were used in confocal imaging of schizont-infected erythrocytes to localize plasmepsin II in mature stages of the parasite development cycle; antibodies clearly labeled the periphery of the parasites. Taken together, these results strongly suggest that, in addition to hemoglobin degradation, plasmepsin II might be involved in cytoskeleton cleavage of infected erythrocytes.