Relative Frequency of Hemolysin and Cytotoxic Necrotizing Virulence Factors in Escherichia coli Isolated From Educational Hospitals of Qazvin, in 2012-2013

Background & aim: Urinary tract infections are the most common type of nosocomial infection. Escherichia coli (E. coli) is the most common cause of urinary tract infections (UTIs) in the community and in clinics. The treatment of these infections is often difficult due to several virulence factors and drug resistance. Adhesions, enzymes and toxins are important virulence factors which promote colonization and pathogenicity of this organism. In the present study, frequency of hemolysin and cytotoxic necrotizing factor-encoding genes and antimicrobial susceptibility were evaluated in E. coli isolates collected from urine samples in the educational hospitals of Qazvin, Iran. Methods: The present cross-sectional study was conducted during 2012-2013. Urine samples were collected from patients with urinary tract infection from different wards of Qazvin teaching hospitals. All of the isolates were identified using standard biochemical and microbiology tests. Antimicrobial susceptibility was further evaluated by Kirby-Baure method according to Clinical and Laboratory Standards Institute guideline. For the presence of genes HLY and CNF, specific primers was used and then using polymerase chain reaction the strains were analyzed and sequenced. Data were analyzed using statistical tests. Results: Altogether, 49 (38.9%) isolates showed the multidrug resistant pattern in which the highest susceptibility rate was shown to amikacin (91.3%) and imipenem (88.9%) and the resistance rate was reported against cefotaxime (83.3%) and ceftazidime (73%), respectively. PCR assay showed that 40 (31.7%) and 24 isolates (19%) were positive for the presence of hly and cnf genes, respectively. Hly and cnf-positive isolates were mostly obtained from patients admitted in internal medicine wards. Conclusion: The findings of this study indicated multidrug resistant isolates and a considerable rate of hemolysin and cytotoxic necrotizing virulence factors in E.coli collected from urine specimens in hospitalized patients in Qazvin, emphasizing the importance of these virulence factors in infection prevention and control strategies.