Antibacterial resistance patterns of extended spectrum β-lactamase -producing enteropathogenic Escherichia coli strains isolated from children.

BACKGROUND AND STUDY AIM: This study aimed to determine the antibacterial resistance patterns of extended spectrum β-lactamase (ESBL)-producing enteropathogenic Escherichia coli (EPEC) isolated from Iranian children and to investigate its genetic patterns.

PATIENTS AND

METHODS

192 non-repeats EPEC isolates were collected from stool samples of the children with and without diarrhoea. The EPEC strains were isolated from 1355 stool specimens obtained from 247 children with diarrhoea (0-10 years old; mean age, 5.5 years) and 1108 children without any gastrointestinal symptoms (0-10 years old; mean age, 6.8 years) during the summer months in three Iranian provinces, Tehran, Ilam and Mazandaran. Strains biochemically identified as E. coli were selected and were identified by the presence of eaeA and bfpA as EPEC virulence genes. Antimicrobial susceptibilities were determined by disc diffusion method. The isolates were confirmed to be ESBL producers by the double disk synergy test (DDST). The β-lactamase genes (blaTEM, blaSHV, blaCTX-M, blaOXA) and insertion sequence ISEcp1 were detected by PCR method.

RESULTS

The highest antibiotic susceptibility was detected to imipenem (100%), followed by gentamicin (82.3%) and ciprofloxacin (79.2%). The highest resistance was detected to cefpodoxime (97.9%), trimethoprim (60.7%), and tetracycline (58.4%), respectively. Totally, 153 EPEC strains (79.7%) were ESBL-producing by DDST test. The PCR showed that 84 (43.8%) EPEC isolates were positive for ESBLs encoding genes. Among 153 ESBLs-producing EPEC, TEM was present in 9.2% of isolates. Also, CTX-M and SHV genes were detected in 7.2% and 7.8%, respectively. The SHV positive strains were associated with the highest resistance rate to tetracycline (56.5%), although the TEM and OXA were associated with the highest resistance rate to gentamicin (23.1%) and ciprofloxacin (21.4%).

CONCLUSIONS

The study revealed that 79.7% of EPEC isolates from Iranian children were ESBL-producing and were comparable with the non ESBL-producing isolates regarding susceptibility to the antibiotics.