Enterotoxigenic Escherichia Coli O169:hut from a Diarrheal Patient: Phylogenetic Group and Antimicrobial Susceptibility.

Enterotoxigenic Escherichia coli (ETEC) is one of the most common pathogenic E. coli pathotypes causing diarrhea in children worldwide. Its enterotoxins, LT and ST, including colonization factors mainly are responsible for human pathogenesis. From 239 rectal swabs of diarrheal patients at Hat Yai and Pattani Hospitals during August 2013 and May 2014, five isolates from only a single E. coli sample demonstrated the possession of estA1, encoding porcine heat-stable enterotoxin (STp). These isolates all belonged to serotype 0169:H Untypeable (HUT) and carried astA, encoding enteroaggregative heat-stable enterotoxin 1. A PCR-based phylogenetic group investigation classified them as members of the virulent E. coli phylogenetic group D. The isolates were resistant to cephalothin, penicillin G, streptomycin, tetracycline and vancomycin. Confirmation of their clonality was conducted by enterobacterial repetitive intergenic consensus sequence PCR typing, which revealed that these ETEC were derived from the same clone. This is the first report of ETEC O169:HUT in southern Thailand.