Study of drug resistance and resistance index of E. coli isolates collected from clinical specimens and determination of blaCTX-M1 gene by PCR in Tabriz.

Background: Overuse of beta lactam antibiotics have led to emergence of Extended spectrum beta lactamases (ESBLS). Production of these enzymes can cause resistance against third generation cephalosporins and hydrolysis of monobactams. Treatments of infectious diseases are difficult and in spite of antimicrobial chemotherapy, there are still some difficulties. This study was conducted to investigate antibiotic susceptibility of and search for presence of blaCTX-M-1 gene in clinical E. coli isolates collected from central laboratory of Tabriz.

Methods: One hundred E. coli isolates were collected from central laboratory of Tabriz. Antibiotic susceptibility tests were carried out according to Kirby- Bauer method using amoxicillin, ceftazidime, ciprofloxacin, cefotaxime, imipenem, gentamicin and nitrofurantoin antibiotics. Confirmatory tests were also performed using combined disk test. Finally PCR was used for detecting blaCTX-M-1gene.

Results: Seventeen out of 100 E. coli isolates contained blaCTX-M-1 gene. All of the isolates were sensitive to nitrofurantoin, while 79% of our isolates were resistant to amoxicillin and 82% were recorded an ESBL producers.

Conclusion: Seventeen percent of E. coli isolates contained blaCTX-M-1gene as a group of ESBL gene indicating presence of other groups of ESBL producing genes which require further studies.