Community Origins and Regional Differences Highlight Risk of Plasmid-mediated Fluoroquinolone Resistant Enterobacteriaceae Infections in Children

Background: Fluoroquinolones are uncommonly prescribed in children, yet pediatric multidrug resistant (MDR) enterobacteriaceae (Ent) infections often reveal fluoroquinolone resistance (FQR). We sought to define the molecular epidemiology of FQR and MDR-Ent in children. Methods: A case-control analysis of children with MDR-Ent infections at 3 Chicago hospitals was performed. Cases were children with third-generation cephalosporin-resistant and/or carbapenem-resistant Ent infections. Polymerase chain reaction and DNA analysis assessed bla and plasmid-mediated FQR (PMFQR) genes. Controls were children with third-generation cephalosporin, fluoroquinolone, and carbapenem-susceptible Ent infections matched by age, source and hospital. We assessed clinical-epidemiologic predictors of PMFQR Ent infection. Results: Of 169 third-generation cephalosporin-resistant and/or carbapenem- resistant Ent isolates from children (median age, 4.8 years), 85 were FQR; 56 (66%) contained PMFQR genes. The predominant organism was Escherichia coli, and most common bla gene bla CTX-M-1 group. In FQR isolates, PMFQR gene mutations included aac6' 1bcr, oqxA/B, qepA and qnrA/B/D/S in 83%, 15%, 13% and 11% of isolates, respectively. FQR E. coli was often associated with phylogroup B2, ST43/ST131. On multivariable analysis, PMFQR Ent infections occurred mostly in outpatients (odds ratio, 33.1) of non-black-white-Hispanic race (odds ratio, 6.5). Residents of Southwest Chicago were > 5 times more likely to have PMFQR Ent infections than those in the reference region, while residence in Central Chicago was associated with a 97% decreased risk. Other demographic, comorbidity, invasive-device, antibiotic use or healthcare differences were not found. Conclusions: The strong association of infection with MDR organisms showing FQR with patient residence rather than with traditional risk factors suggests that the community environment is a major contributor to spread of these pathogens in children.