Virulence and Antimicrobial Resistance in spp. from a Peruvian Pediatric Cohort.

The presence of virulence factors (VFs) and mechanisms of quinolones and macrolide resistance was analyzed in spp. from a pediatric cohort study in Lima. In 149 isolates (39 and 24 from diarrheic cases; 57 and 29 from controls), the presence of the and genes and marker was established. Nalidixic acid, ciprofloxacin, erythromycin, and azithromycin susceptibilities were established in 115 isolates and tetracycline-susceptibility was established in 100 isolates. The presence of mutations in the , and genes was determined. The gene and all genes from the operon were significantly more frequent among ( < 0.0001); the marker was more frequent in ( < 0.0001). No differences were observed in VFs between cases and controls. Almost all isolates were tetracycline-resistant; nalidixic acid and ciprofloxacin resistance reached levels of 90.4% and 88.7%, respectively. Resistance to macrolides was 13% ( 4.3%; 26.1%). Resistance to ciprofloxacin was related to GyrA Thr86 substitutions, while 13 of 15 macrolide-resistant isolates possessed a mutation (A2075G). Differences in the presence of VFs and alarming levels of resistance to tested antimicrobial agents were observed among and .