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AbstractObjective:To describe common pathogens and antimicrobial resistance patterns for healthcare-associated infections (HAIs) among pediatric patients that occurred in 2015–2017 and were reported to the Centers for Disease Control and Prevention’s National Healthcare Safety Network (NHSN).Methods:Antimicrobial resistance data were analyzed for pathogens implicated in central line-associated bloodstream infections (CLABSIs), catheter-associated urinary tract infections (CAUTIs), ventilator-associated pneumonias (VAPs), and surgical site infections (SSIs). This analysis was restricted to device-associated HAIs reported from pediatric patient care locations and SSIs among patients <18 years old. Percentages of pathogens with nonsusceptibility (%NS) to selected antimicrobials were calculated by HAI type, location type, and surgical category.Results:Overall, 2,545 facilities performed surveillance of pediatric HAIs in the NHSN during this period. Staphylococcus aureus(15%), Escherichia coli(12%), and coagulase-negative staphylococci (12%) were the 3 most commonly reported pathogens associated with pediatric HAIs. Pathogens and the %NS varied by HAI type, location type, and/or surgical category. Among CLABSIs, the %NS was generally lowest in neonatal intensive care units and highest in pediatric oncology units. Staphylococcusspp were particularly common among orthopedic, neurosurgical, and cardiac SSIs; however, E. coliwas more common in abdominal SSIs. Overall, antimicrobial nonsusceptibility was less prevalent in pediatric HAIs than in adult HAIs.Conclusion:This report provides an updated national summary of pathogen distributions and antimicrobial resistance patterns among pediatric HAIs. These data highlight the need for continued antimicrobial resistance tracking among pediatric patients and should encourage the pediatric healthcare community to use such data when establishing policies for infection prevention and antimicrobial stewardship.

AbstractObjective:Describe common pathogens and antimicrobial resistance patterns for healthcare-associated infections (HAIs) that occurred during 2015–2017 and were reported to the Centers for Disease Control and Prevention’s (CDC’s) National Healthcare Safety Network (NHSN).Methods:Data from central line-associated bloodstream infections (CLABSIs), catheter-associated urinary tract infections (CAUTIs), ventilator-associated events (VAEs), and surgical site infections (SSIs) were reported from acute-care hospitals, long-term acute-care hospitals, and inpatient rehabilitation facilities. This analysis included device-associated HAIs reported from adult location types, and SSIs among patients ≥18 years old. Percentages of pathogens with nonsusceptibility (%NS) to selected antimicrobials were calculated for each HAI type, location type, surgical category, and surgical wound closure technique.Results:Overall, 5,626 facilities performed adult HAI surveillance during this period, most of which were general acute-care hospitals with <200 beds. Escherichia coli(18%), Staphylococcus aureus(12%), and Klebsiellaspp (9%) were the 3 most frequently reported pathogens. Pathogens varied by HAI and location type, with oncology units having a distinct pathogen distribution compared to other settings. The %NS for most pathogens was significantly higher among device-associated HAIs than SSIs. In addition, pathogens from long-term acute-care hospitals had a significantly higher %NS than those from general hospital wards.Conclusions:This report provides an updated national summary of pathogen distributions and antimicrobial resistance among select HAIs and pathogens, stratified by several factors. These data underscore the importance of tracking antimicrobial resistance, particularly in vulnerable populations such as long-term acute-care hospitals and intensive care units.

Background:Carbapenem-resistant Acinetobacter baumannii(CRAB) are an urgent public health threat because they cause healthcare-associated infections that are difficult to treat and can spread in healthcare environments. Acinetobacterspp may develop resistance to carbapenems through various mechanisms, including decreased permeability, overexpression of efflux pumps, and production of carbapenemases. Carbapenemases found in CRAB commonly belong to the group of carbapenem-hydrolyzing class D β-lactamases, which can be either intrinsic or acquired. The most clinically relevant class D enzymes are the OXA-23-like, OXA-24/40–like, and OXA-58–like because they are commonly plasmid mediated and thereby have the potential for rapid dissemination. We describe the molecular epidemiology of CRAB in the United States using a convenience sample of isolates collected from reference submissions, an isolate-based surveillance system, and the Antibiotic Resistance Laboratory Network (ARLN). Methods:Beginning in August 2017, 7 public health laboratories in the ARLN began testing CRAB isolates submitted by participating sentinel clinical laboratories across their region. Carbapenem-resistant isolates were identified by resistance to imipenem, meropenem, or doripenem. Testing included molecular detection of 4 targeted carbapenemase genes: blaKPC, blaNDM, blaVIM, and blaIMP. Participating labs reported testing results to CDC at least monthly. A separate collection of isolates from CDC reference and surveillance activities between 2013 and 2015 underwent whole-genome sequencing (WGS) to evaluate the presence of acquired carbapenemase genes, including class D OXA-variants. Results:From August 2017 through July 2019, the ARLN tested 2,368 CRAB isolates across 44 states. Only 12 (0.5%) of these harbored a bla-gene: blaKPC (n = 5), blaNDM (n = 5), blaIMP (n = 1), and blaVIM (n = 1). Of 95 reference and surveillance isolates sequenced, none harbored these targeted carbapenemases. However, 69 (73%) harbored at least 1 acquired class D OXA gene; OXA-23 was the most commonly acquired OXA variant (n = 46, 48.4%). Conclusions:Using a multipronged approach, our studies indicate that the presence of class D β-lactamases of the OXA type are common in CRAB among surveillance and reference samples that underwent WGS analysis. Other acquired carbapenemases appear to be rare. To prevent the spread of highly resistant CRAB, particularly those carrying the targeted, emerging carbapenemase genes, continued testing, and rapid infection control are necessary to improve patient safety and maintain situational awareness.Funding:NoneDisclosures:None

Background:Carbapenem-resistant Pseudomonas aeruginosa(CRPA) is a frequent cause of healthcare-associated infections (HAIs). The CDC Emerging Infections Program (EIP) conducted population and laboratory-based surveillance of CRPA in selected areas in 8 states from August 1, 2016, through July 31, 2018. We aimed to describe the molecular epidemiology and mechanisms of resistance of CRPA isolates collected through this surveillance. Methods:We defined a case as the first isolate of P. aeruginosaresistant to imipenem, meropenem, or doripenem from the lower respiratory tract, urine, wounds, or normally sterile sites identified from a resident of the EIP catchment area in a 30-day period; EIP sites submitted a systematic random sample of isolates to CDC for further characterization. Of 1,021 CRPA clinical isolates submitted, 707 have been sequenced to date using an Illumina MiSeq. Sequenced genomes were classified using the 7-gene multilocus sequence typing (MLST) scheme, and a core genome MLST (cgMLST) scheme was used to determine phylogeny. Antimicrobial resistance genes were identified using publicly available databases, and chromosomal mechanisms of carbapenem resistance were determined using previously validated genetic markers. Results:There were 189 sequence types (STs) among the 707 sequenced genomes (Fig. 1). The most frequently occurring were high-risk clones ST235 (8.5%) and ST298 (4.7%), which were found across all EIP sites. Carbapenemase genes were identified in 5 (<1%) isolates. Overall, 95.6% of the isolates had chromosomal mutations associated with carbapenem resistance: 93.2% had porinD-associated mutations that decrease membrane permeability to the drugs; 24.8% had mutations associated with overexpression of the multidrug efflux pump MexAB-OprM; and 22.9% had mutations associated with overexpression of the endogenous β-lactamase ampC. More than 1 such chromosomal resistance mutation type was present in 37.8% of the isolates. Conclusions:The diversity of the sequence types demonstrates that HAIs caused by CRPA can arise from a variety of strains and that high-risk clones are broadly disseminated across the EIP sites but are a minority of CRPA strains overall. Carbapenem resistance in P. aeruginosawas predominantly driven by chromosomal mutations rather than acquired mechanisms (ie, carbapenemases). The diversity of the CRPA isolates and the lack of carbapenemase genes suggest that this ubiquitous pathogen can readily evolve chromosomal resistance mechanisms, but unlike carbapenemases, these cannot be easily spread through horizontal transfer.Funding:NoneDisclosures:None