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

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 community and clinic. 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 this study, frequency of hemolysin and cytotoxic necrotizing factor-encoding genes and antimicrobial susceptibility were evaluated in E. coli isolates collected from urine samples in educational hospital of Qazvin.
In this cross-sectional descriptive study between 2012 and 2013, 126 E. coli isolates were collected from urine samples in educational hospital of Qazvin. All isolates were identified using standard microbiological and biochemical techniques. Antimicrobial susceptibility was further evaluated by Kirby-Baure method according to Clinical and Laboratory Standards Institute guideline. Frequency of hly and cnf genes was determined using specific primers by PCR and sequencing methods. Statistical analysis was performed for descriptive statistics including frequencies and cross tabulation of microbiological, clinical, and demographic characteristics using the computer software program SPSS version 18.
In total, 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.
The findings of this study show 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.