ctx-m-15 type β-lactamases from clinical isolates of escherichia coli by polymerase chain reaction and dna sequencing

Background: e. coli is a common cause of urinary tract infection and bacteremia in humans. that is frequently resistant to β-lactam antibiotics. objectives: the aim of this study was to determine the antibiotic resistance and ctx-m extended-spectrum β-lactamases (esbl) carrying e. coli isolated in hospitals from two different areas in iran. methods: in this descriptive cross-sectional study, 93 clinical isolates of e. coli were collected from urine culture of inpatients in mashhad and qom hospitals from august 2013 to february 2014. bacteria were re-confirmed by microgen kit. antimicrobial and esbl tests were performed using by standard disc diffusion method. polymerase chain reaction (pcr) was used for detection of plasmid mediated ctx-m-1 and ctx-m-2 esbls. four of the blactx -m genes were sequenced. statistical analysis carried out using spss (version 16) software and chi-square test. results: high prevalent isolates were resistant to ampicillin, cephalothin, nalidixic acid and cotrimoxazole, but sensitive to imipenem, nitrofurantoin and amikacin. the esbl phenotype was detected in 48 (51.6%) isolates, 42 of which were carrying blactx -m gene. there was no significant difference between the β-lactamase-producing bacteria from the two studied cities. 81% and 85% of blactx -m carriers from hospitals in qom and mashhad were respectively found to have ctx-m-1 esbl, whereas none of them showed ctx-m-2 esbl cluster. blactx-m-15 was found in four selected bacteria by sequencing. conclusions: this study showed a high rate of ctx-m-1 cluster and also presence of ctx-m-15 esbl in two different areas of iran, which emphasize the need for employing an excellent management program in antibiotic therapy.