The antibiotic resistance and molecular detection of extended spectrum β-lactamases TEM and SHV in multi drug resistance E.coli isolated from urine of hospitalized patients in Kerman, 2007-8

Escherichia coli is the most common cause of nosocomial infection including urinary tract infections (UTIS). Due to the presence of various resistance mechanisms against antibacterial agents specially extended spectrum β -lactamases (ESBLs), the treatment of infections caused by these bacteria is problematic. Since detection of bacterial resistance and SHV and TEM type ESBLs which are the common type of β - lactamases is required for a better management of infection caused by these bacteria, the aim of this study was to determine the antibacterial resistance pattern and the prevalence of bla SHV and blaTEM lactamases genes in clinical isolates of E.colifrom urine of hospitalized patient in Kerman. This study was performed on 115 E.coli strains isolated from urine specimens of hospitalized patients in 3 hospitals in Kerman. Agar dilution method was used for determination of minimum inhibitory concentration to selected antibacterial agents. ESBLs production was detected by combined disc method. TEM and SHV type β -lactamases were detected by PCR method using plasmid and chromosomal DNA. Of the total isolated bacteria, 86(74.7%) showed resistance to 3 antibacterial agents from different classes and were considered as multiple drug resistance (MDR). Totally, 76 (66%) of the isolates produced ESBLs. The PCR assay performed on the plasmid and chromosomal DNA, totally 48 (4107%) of the isolates showed TEM, 39 (33.9%) showed SHV, and 20 (17.3%) of the isolates had both TEM and SHV genes.
The lowest level of resistance, only in 7 of the isolates (14.7%), was seen towards ceftizoxim. The highest level of resistance was detected to amoxicillin and trimethoprim /sulfamethoxazole which was in the order of 108 (94%) and 110 (95%) isolates, respectively. MDR trait in urine isolates is common in this area. Due to high resistance to trimethoprim /sulfamethoxazole and amoxicillin, these antibacterial agents are not recommended for treatment of urinary tract infections. In general, the prevalence of TEM gene was found to be much higher than the SHV.