Identification and determination of tetracycline resistance genes in uropathogenic Escherichia coli isolates in Sistan

Certain strains of extraintestinal pathogenic E. coli can cause urinary tract infection (UTI) in humans. Today, unnecessary consumption of antibiotics has led to resistance in bacterial populations. The aim of this study was to determine the tetracycline resistance genes and to evaluate the prevalence of antibiotic resistance among E. coli isolates collected from patients with UTI.In this descriptive cross-sectional study, 350 urine samples were collected from patients with UTI who were referred to the teaching hospital in Zabol during 6 months. E. coli was identified by conventional bacteriological test methods. Antibiotic susceptibility test was performed as recommended by the Clinical Laboratory Standards Institute (CLSI) using disk diffusion method. All tetracycline-resistant isolates were then examined for presence of the tetA, tetB and tetC genes.Of the 100 isolates of E. coli, the most antibiotic resistance was related to tetracycline (57%) and the least antibiotic resistance was related to ceftazidim (34%). Resistance to other antibiotics ceftriaxone, aztreonam and cefotaxime were 44%, 44% and 40%; respectively. Among tetracycline resistant isolates, 32 isolates (56.14%), had tetA gene and tetB and tetC genes were found in 28 (49.12%) and 6 (10.52%) isolates respectively. 16 (28.07%) and 3 (5.26%) isolates were positive for both genes (tetA and tetB) and three genes, and 14 (24.56%) isolates were negative for them.Resistance to tetracycline and other antibiotics, and the presence of tetA and tetB genes in UPEC strains are alarming signs in Sistan. The current study strongly recommends restricted consumption of antibiotics including tetracycline. Further studies are needed in other parts of the country to take more appropriate measures than common therapies.