Low intestinal colonization of Escherichia coli clone ST131 producing CTX-M-15 in Jordanian infants.

Over a period of 3 years' study (2012-2014), a total of 518 faecal samples were collected and cultured to isolate Escherichia coli. Of these, 338 (65.3%) E. coli isolates were recovered from infants, and 142/338 (42%) were multidrug-resistant (MDR) to ≥ 3 drug classes using the antimicrobial susceptibility disc diffusion method. A total of 125/142 (88%) of E. coli isolates were extended-spectrum β-lactamase (ESBL) producers. blaCTX-M-15 types were observed in 80/125 (64%) of the isolates, and 60/80 (75%) were positive for blaCTX-M-15. Out of 338 E. coli isolates, 9 (2.6%) were positive for ST131/O25b clone and each isolate was associated with several plasmids of different sizes (1-21.2 kb). The identities of these nine isolates were confirmed by sequencing for presence of pabB (347 bp) and trpA (427 bp) genes. This study demonstrates low prevalence rate of the highly virulent E. coli ST131 clone producing blaCTX-M-15 in the intestines of Jordanian infants.