Molecular characterization of ESBL-producing Escherichia coli isolates from ICU patients in Tabriz - Iran

BACKGROUND AND ABJECTIVEE. coli is a gram-negative, rod-shaped bacterium and a member of the Enterobacteriaceae bacterial family that is considered an opportunistic bacterial pathogen with high pathogenic features. Also, antibiotic resistance and relative issues, such as Extended-spectrum β-lactamase (ESBL) production, have risen in E. coli in recent decades. The molecular screening of antibiotic resistance can give physicians an excellent perspective to choose the right therapeutic agent and help scientists design alternative therapeutic approaches. Therefore, this study was conducted to determine the prevalence of ESBL production-related genes, such as blaOXA-۲۳, blaOXA-۴۸, blaSHV, and blaNDM-۱.MATERIALS AND METHODS۵۰ E. coli isolates were examined in this study. Isolates identification is performed by biochemical (IMViC tests) and molecular (amplifying ۱۶s rRNA gene) methods. Antibiotic resistance pattern evaluated by disk diffusion method via ۱۰ different antibiotic disks including ceftazidime (۳۰ μg), imipenem (۱۰ μg), gentamicin (۱۰ μg), trimethoprim-sulfamethoxazole (۱.۲۵/۲۳.۷۵ μg), ceftriaxone (۳۰ μg), tetracycline (۳۰ μg), aztreonam (۳۰ μg), ampicillin (۱۰ μg), amikacin (۳۰ μg), and ciprofloxacin (۵ μg) according to CLSI guidelines. Double disk synergy test (DDST) was performed for morphological determination of ESBL-producing isolates. In addition, the frequency of ۴ ESBL-related resistance genes, including blaOXA-۲۳, blaOXA-۴۸, blaSHV, and blaNDM-۱, was determined by PCR in ESBL-producing isolates.RESULTS AND DISCUSSIONOf the ۵۰ isolates examined in this study, ۴۸% were isolated from men and ۵۲% from women. According to previous studies conducted in Iran, this bacterium seems problematic in Iranian women. Since this bacterium causes disorders such as preterm birth (PTB) and asymptomatic bacteriuria (ABU) during the pregnancy period. These disorders can result in abortion, early delivery of the fetus, and also financial loss. It seems Screening and diagnostic tests for this bacterium in pregnant women seem necessary. In this study, all isolates were resistant to at least one of the antibiotic groups. Also, ampicillin has the highest resistance rate among other antibiotics. The prevalence importance of ampicillin-resistant E. coli strains in patients has been highly investigated in previous studies. This resistance occurred due to indiscriminate administration and the availability of ampicillin in the market. Consequently, many E. coli strains have developed β-lactamases encoded by SHV and TEM genes in order to inactivate ampicillin. Thus, the prescription and use of ampicillin to treat this bacterium should be limited. ۲۴% of E. coli strains were determined as ESBL producers. Furthermore, in the current study, ESBL-related genes, including OXA-۴۸, OXA-۲۳, NDM-۱, and SHV frequency, were ۸.۳۳%, ۵۸.۳۳%, ۳۳.۳۳%, and ۵۰% respectively. Comparing the results of this study with a meta-analysis that was conducted recently indicated that the SHV gene is increased in the past few years among Iranian patients. Also, the frequency of the NDM-۱ gene in this study is higher than in similar studies conducted in Pakistan and Taiwan. Therefore, it seems the presence of NDM-۱ in E. coli strains in Iran can be problematic.CONCLUSIONIn summary, E. coli isolates with high antibiotic resistance patterns harboring ESBL-producing relative genes were identified in this study. However, the lack of molecular pathotyping of E. coli isolates can be a major limitation of the present study. Like what was done in the present study, routine screening of ESBLs, to prevent the spreading of ESBL-producing isolates in hospital environments was suggested.

کلیدواژه ها:

Antimicrobial resistance ، E. coli ، ESBLs