Genetic detection of extended-spectrum beta-lactamase-containing Escherichia coli isolates and vancomycin-resistant enterococci in fecal samples of healthy children.

One hundred twelve fecal samples of healthy children were recovered in Portugal during October 2007 and February 2008 and were tested for extended-spectrum beta-lactamases (ESBLs) containing Escherichia coli isolates and vancomycin-resistant enterococci (VRE). Three of the 112 fecal samples (2.7%) harbored ESBL-positive E. coli isolates and the bla(CTX-M-1), bla(TEM-52), and bla(SHV-12) genes were identified in these isolates. The bla(TEM-52)-containing isolate showed a phenotype of multiresistance that included fluoroquinolones, tetracycline, trimethoprim-sulfamethoxazole, and chloramphenicol; sul1, sul3, and cmlA genes were detected in this isolate, in addition to two amino acid changes in GyrA (Ser83Leu + Asp87Asn) and one in ParC protein (Ser80Ile). The ESBL isolates corresponded to phylogroup A (one isolate), B1 (one isolate), and D (one isolate). vanA-containing Escherichia faecium isolates were detected in 13 of the 112 fecal samples (11.6%), and vanC-1 isolates were found in 2 samples. A diversity of resistance genes [(tet(M), tet(L), erm(B), aph(3')-IIIa, ant(6)-Ia, catA, and vat(E)] were found in VRE isolates. These results show that the intestinal tract of healthy children constitutes a reservoir of ESBL-containing E. coli and VRE isolates.