594. A Multi-Centered Study of the Clinical and Molecular Epidemiology of AmpC Cephalosporinase-Producing (AmpC) Enterobacteriaceae (Ent) Infections in Children

Abstract

BackgroundAmpC producing Ent are an important cause of multidrug-resistant (MDR) infections in pediatrics. Since most AmpC Ent studies have been conducted in adults, we characterized the molecular epidemiology of AmpC Ent strains with transmissible resistance and identified factors associated with AmpC Ent infections in children.MethodsA case–control study of children (0–18 years) at 4 Chicago hospitals during 2011–18 was performed. Cases were 44 children with infections due to Ent harboring an AmpC as detected by DNA microarray (Check-Points®). PCR, DNA sequencing, MLST, and phylogenetic analyses were performed. Controls (ctrls) were 132 children with expanded-spectrum cephalosporin-susceptible Ent infections matched by age and hospital. Demographics; residence; comorbidities; device, antibiotic, and healthcare exposures were evaluated. Predictors of AmpC Ent infection were assessed by logistic regression.ResultsThe median age of AmpC Ent patients was 3.0 years; 50% were male. Of blaAmpC genes, 68% were blaACT/MIR-type and 25% blaCMY-type. Predominant organisms were Enterobacter cloacae (59%) and Escherichia coli (32%); 27% of AmpC E. cloacae belonged to ST114 and 62% co-harbored a blaESBL gene, predominately blaSHV (94%). Most AmpC E. coli strains were unrelated; 71% carried blaCMY, 64% belonged to phylogroups B2/D, and 50% co-harbored blaCTX-M. On bivariate analysis vs. ctrls, AmpC Ent infections were more likely to be respiratory (39% vs. 18%, P < 0.01) and less likely to be urinary tract (41% vs. 67%, P < 0.01) or community-acquired (14% vs. 33%, P < 0.02). By multivariable analysis, children with AmpC Ent infections were more likely to be nonwhite, non-black, non-Hispanic (OR 4.7, CI 1.4–16.1) and have infections due to Enterobacter (OR 7.7, CI 3.5–17). Differences in gender, healthcare location, residential neighborhood, antibiotic exposures, comorbidities, devices or outcomes were not found.ConclusionAmpC Ent infections often had healthcare onset, were due to Enterobacter, and occurred in nonwhite, non-black, non-Hispanic children. AmpC Ent commonly co-harbored blaSHV and blaCTX-M ESBL genes which affects therapeutic options and suggests the need for contact precautions. Control of AmpC Ent infections in children will require validating sources and risk factors.Disclosures All authors: No reported disclosures.