Abstract. Few studies have examined the influence of individual-, household-, and community-scale risk factors on carriage of resistant commensal bacteria. We determined children's medical, agricultural, and environmental exposures by household, pharmacy, and health facility surveys and Escherichia coli cultures of children, mothers' hands, household animals, and market chickens in Peru. Among 522 children with a positive stool culture, by log-binomial regression, using "any antibiotic" and 1-14 (versus 0) sulfa doses in the past 3 months increased children's risk, respectively, for ampicillin-and sulfamethoxazole-resistant E. coli carriage ( P = 0.01-0.02). Each household member taking "any antibiotic" increased children's risk for sulfamethoxazole-and multidrug-resistant E. coli carriage ( P < 0.0001). Residence in a zone where a larger proportion of households served home-raised chicken (as contrasted with intensively antibiotic-raised market chicken) protected against carrying E. coli resistant to all drugs ( P = 0.0004-0.04). Environmental contamination with drug-resistant bacteria appeared to significantly contribute to children's carriage of antibiotic-resistant E. coli .

Streptococcus pneumoniae isolates were obtained from nasopharyngeal swabs taken from children living in a low socioeconomic area of Lima, Peru, to determine the rates of antimicrobial resistance and serotype distribution. A total of 146 nasopharyngeal isolates were collected from children from 3 to 38 months of age.