Prevalence of blaCTX-M, blaSHV, and blaTEM Genes in Escherichia coli Strains Isolated From Urinary Tract Infection Samples of Patients in the Intensive Care Unit in Qom, Iran

Escherichia coli is considered as one of the causes of opportunistic infections. Nowadays, due to the increase in drug resistance, the treatment of these infections has become very difficult and they are recognized as the main causes of death in hospitalized patients.

The aim of this study was to determine the prevalence of blaTEM, blaSHV, and blaCTX-M genes in E. coli strains isolated from the urinary tract infection in patients in Intensive Care Units of three different hospitals in Qom, Iran.

This study was conducted in three months from October to December 2014. A total of 200 E. coli samples were taken from the patients with urinary tract infections in Intensive Care units of Qom hospital. The disc diffusion method was used to determine the susceptibility pattern of antibiotic and phenotypic confirmatory tests for screening of the expanded spectrum beta-lactamase (ESBL) isolates. The presence of blaTEM, blaSHV, and blaCTX-M genes was evaluated by the polymerase chain reaction (PCR) assay.

Of 200 samples, ampicillin (96%) and nitrofurantoin (19.5%) showed the highest and lowest drug resistance, respectively. A total of 156 isolates (78%) were identified as ESBLs using the phenotypic method. Moreover, 76 (38%), 90 (45%), and 123 (61.5%) isolates consisted of blaCTX-M, blaSHV, and blaTEM, respectively.

Overall, the findings of this study showed that blaTEM was the most common gene with a frequency of 61.5% in ESBL E. coli.