LAUSR

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 blaCTX-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.