To investigate the epidemiology of fecal carriage of CTX-M type extended-spectrum beta-lactamases (ESBL)-producing organisms among children and their household contacts.

Fecal carriage with CTX-M-producing organisms was studied in 53 children and 172 household members. Molecular methods were used to characterize the isolates.

The children were mostly healthy and hospitalized for relatively mild febrile illnesses. Overall, the prevalence of fecal carriage of CTX-M-producing bacteria was 43.5% (admission children, 37.7%; household children, 20.7% and household adults, 50.3%). Household colonization index (defined by number of household carriers/total number of members) was significantly higher among families with at least one individual having a history of prolonged (>3 months) out-of-town residence in the previous year (mean±standard deviation; yes group, 0.67±0.36 vs. no group, 0.39±0.28, P=0.009) and was inversely correlated with the living space per person (R-square=0.139, P=0.006). Among 29 households with at least two carriers of CTX-M-producing enterobacteria, six clusters of clonally related strains were shared by 15 individuals from seven households; with both intra- and inter-household transmission.

CTX-M beta-lactamases may spread extensively amongst family members in the home.