Prevalence of Fecal Carriage of CTX-M-15 Beta-Lactamase-Producing Escherichia coli in Healthy Children from a Rural Andean Village in Venezuela

Abstract

Objectives: Antimicrobial resistant extended-spectrum-β-lactamase-producing Enterobacteriaceae (ESBL-PE) have been shown to be present in healthy communities. This study examined healthy children from the rural Andean village of Llano del Hato, Mérida, Venezuela, who have had little or no antibiotic exposure to determine the prevalence of fecal carriage of ESBL-producing Escherichia coli (ESBL-EC).

Methods: A total of 78 fecal samples were collected in healthy children aged from 1 to 5 years. ESBL-EC were selected in MacConkey agar plates with cefotaxime and further confirmed by the VITEK 2 system. ESBL were phenotypically detected and presence of bla genes and their variants were confirmed by molecular assays. Determination of phylogenetic groups was performed by PCR amplification. Risk factors associated with fecal carriage of ESBL-EC-positive isolates were analyzed using standard statistical methods.

Results: Of the 78 children studied, 27 (34.6%) carried ESBL-EC. All strains harbored the bla_CTX-M-15 allele. Of these, 8 were co-producers of bla_TEM-1, bla_TEM-5, bla_SHV-5 or bla_SHV-12. Co-resistance to aminoglycosides and/or fluoroquinolones was observed in 9 strains. 51.9% of ESBL-EC isolates were classified within phylogroup A. A significant, positive correlation was found between age (≥2.5 - ≤5 years), food consumption patterns and ESBL-EC fecal carriage.

Conclusion: This is the first study describing the high prevalence of fecal carriage of ESBL-EC expressing CTX-M-15- among very young, healthy children from a rural Andean village in Venezuela with scarce antibiotic exposure, underlining the importance of this population as a reservoir.

Keywords: CTX-M-15; Enterobacteriaceae; Extended-spectrum-β-lactamases; Venezuela; fecal carriage; healthy children.

Figure 1

Forest plot showing the association of the fecal carriage of ESBL-EC with epidemiological variables. The values of Cramer’s V confirmed a relatively strong effect size (0.447) of the variable ≥ 2.5 years – ≤5 years, and a moderate effect (0.367) of the variable “food ingestion of animal origin.”

Figure 2

Hierarchical clustering dendogram demonstrating phylogenetic and resistance profiling of ESBL-EC. Analysis based on clinical, epidemiological and molecular characteristics identified 2 distinct clusters of child fecal carriage of ESBL-EC. Note the presence of 2 subgroups (major cluster) with similar relationships of 100%. Children with a lower degree of similarity (≤65%) were observed in the minor cluster. AMK: amikacin; CIP: ciprofloxacin; GEM: gentamicin; N°: children (ESBL-EC positive); NAL: nalidixic acid; PG: phylogenetic group; Rest. Profile: resistance profile.