Comparison of Escherichia coli Virulence in Nosocomial UTIs Patients from Different Units of Shahid Faghihi Hospital, Shiraz, Iran

Background and Objectives: Urinary tract infections (UTIs) are the most frequent nosocomial infections, predominantly associated with catheterization of patients. The major causative agent of these infections is uropathogenic Escherichia coli (UPEC). UPECs present several virulence factors that allow them to protect themselves from the hosts’ immune systems, colonize the urinary tract and injure the hosts. The aim of this study was to compare the frequencies of several virulence factors in UPEC isolates from hospitalized UTIs patients in different units of the Shahid Faghihi hospital, Shiraz, Iran. Materials and Methods: During eight months, 49 E. coli strains were isolated from midstream urine samples of inpatients with UTIs, hospitalized in different units of the Shahid Faghihi hospital. DNA extracts of these isolates were evaluated by PCR technique to find the prevalence of virulence genes encoding the conjugal transfer surface exclusion protein TraT (traT gene), the outer membrane protease T (ompT gene), the haemolysin (hlyD gene), and the cytotoxic necrotizing factor type 1 (cnf1 gene). The results were then analyzed statistically by SPSS software. Results: Overall, the toxin encoding genes including cnf1 and hlyD had the lower prevalence in the UPEC isolates than the virulence gene that contributes to the protection of UPECs against host’s immune system (ompT) and the gene that mediates the UPECs’ resistance to serum (traT). Separately, frequencies of the tested virulence genes in the UPEC isolates of UTIs inpatients from different units of the hospital including Internal, Surgery, Intensive care, Neurology, Women’s, and Skin units were as follows, respectively: 8.7%, 0.0%, 25.0%, 12.5%, 50.0%, and 0.0% for cnf1 gene. 13.0%, 16.7%, 12.5%, 0.0%, 100%, and 50.0% for hlyD gene. 56.5%, 66.7%, 50.0%, 25.0%, 50.0%, and 50.0% for ompT gene. 69.6%, 50.0%, 75.0%, 50.0%, 50.0%, and 100% for traT gene. Results showed no significant difference (p > 0.05) in the frequencies of the tested virulence genes in the isolates from hospitalized patients in different units of the hospital with the exception of the hlyD gene which was significantly (p = 0.03) more prevalent in the UPECs from hospitalized patients in the Women s unit in comparison to that in the other units of the hospital. Conclusion: Relatively high prevalence of the virulence factors in the UPECs revealed that these isolates were virulent and could overcome the hosts’ immune system and cause UTIs. As the nosocomial UPECs usually are more resistant to the antibiotic therapy, there is a need to find better medical approaches on the basis of anti-virulence factors interventions for the prevention and treatment of UTIs. Also, applying the sterile equipment and aseptic techniques for catheterization of hospitalized patients are mandatory.