Fecal carriage rates of extended-spectrum β-lactamase-producing Escherichia coli among antibiotic naive healthy human volunteers.

INTRODUCTION: Higher prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli fecal carriage has been reported in the nosocomial setting than in the community. We tried to determine the fecal carriage of ESBL-producing E. coli among healthy volunteers in a relatively isolated community.
MATERIALS AND METHODS: This study was conducted on 115 healthy adult volunteers from whom one fecal sample was collected and was plated on selective media. Each morphotypes were identified, characterized, and ESBL phenotype was confirmed by double-disk potentiation method. Molecular characterization of ESBL gene was done using multiplex polymerase chain reaction and pulse-field gel electrophoresis (PFGE) was done to identify their clonal relation.
RESULTS: ESBL-producing E. coli had a prevalence of 19% (22/115) among the healthy volunteers in the community. CTX-M was the predominant type, showed a presence 95.5% (21/22), TEM 63%, SHV 9%, and both TEM and CTX-M were present in 63.6% (14/22), all three present in 4.5% (1/22). The lineage using PFGE showed a single clone in 17 isolates. Seven isolates were type A (all TEM & CTX-M), six were type A1 (all TEM & CTX-M except 2), four were type A2 (all CTX-M), and three belonged to types B, C, and D respectively
Conclusion: High prevalence rate of 19% in the community indicated by this study implies the possibility of sustained ESBL carriage even among isolated population, which could serve as a reservoir for enriching the ESBL pool in the hospital. Clonal relations also indicate a possible epidemiological source that needs to be evaluated.