Backcground: Escherichia coli (E. coli) is the most common cause of urinary tract infection (UTI). Virulence factors are mainly responsible for the severity of these emerging infections.
Aims: To analyze virulence factors and resistance phenotype to quinolones and fluoroquinolones in a collection of E. coli strains isolated from UTIs with previously known phylogenetic groups.
Place and Duration of Study: Department of Biology and Biotechnology, An-Najah N. University, Palestine, during May-December 2012.
Methodology: Fifty clinical E. coli isolates were previously recovered from urine specimens obtained from patients suffered from urinary tract infections at Thabet Hospital, Tulkarm-Palestine. Multiplex PCR technique was used to detect the presence of 18 virulence genes and ERIC-PCR was used to detect the heterogeneity of these strains. All E. coli isolates were examined for resistance to different antibiotics using disk diffusion method.
Results: It is found that the prevalence of virulence genes ranged from 0% for P-fimbria adhesion variant 1 (pap G I) allele and a- hemolysin (hly A) to 86% for Type1 fimbriae adhesion (fim H) and Serum resistance-associated gene (tra T) in strains tested. The results showed that the mean virulence score for group D was 8.2 and ranged from 2 to15, while for group A was 6.2 and ranged from 1 to14 (P=6.2 x 10-4). The mean virulence score for strains resistant to fluoroquinolones and /or quinolones was 7.3, while for strains sensitive to both fluoroquinolones and quinolones was 8.1. Quinolones and/or fluoquinolones sensitive strains related to group D showed an increased prevalence of catecholate siderophore receptor (iron) than resistant strains. It was also found that traT gene was the most common prevalence among strains resistant to nalidixic acid, fluoroquinolones and trimethoprim/sulphamethoxazole and it was 90.1% (30/33), 95.8 (23/24) and 90.6% (29/32), respectively. ERIC-PCR revealed that the 50 isolates were genetically diverse and comprised a heterogeneous population with at total 10 ERIC-PCR profiles at a 50% similarity level.
Conclusion: The molecular analysis of strains belonged to groups A and D, results showed that group D had higher mean virulence score than group A. It seems that there is no single virulence factor or virulence profile that is entirely specific to UTI in general.