Virulence Factors and Phylogenetic Grouping in Uropathogenic Isolates of Escherichia coli Recovered from Thabet Hospital-Tulkarm, Palestine

Escherichia coli (E. coli) is one of the most common bacteria that cause urinary tract infection (UTI). This pathogen is reported in 50-90% of all uncomplicated urinary tract infections. This study aimed to analyze phylogenetic groups, virulence factors and antibiotic resistance phenotype in a collection of fifty E. coli strains, isolated from urine specimens obtained from suspected cases of UTIs, of inpatients and outpatients at Thabet Hospital during May-December 2012. Phylogenetic analysis was detected by multiplex polymerase chain reaction (PCR). Results showed that the majority of the studied isolates, namely 36 (72%) strains, belonged to group D. Thirteen (26%) strains were assigned to group A, while 1 (2%) strain was belonged to group B1. There was a significant difference between the prevalence of these groups at P < 0.001. The rate of resistance of these isolates to different antibiotics was detected by disk diffusion method, and has ranged from 24% for Gentamicin to 100% for Cefazoline and Erythromycin. These results showed that the mean antibiotic resistance scores were 8.4 and 6.5 for strains belonged to group D and group A, respectively, and statically significant difference at P = 6.2 x 10. The prevalence of antibiotic resistance tested in each strain ranged from 14.3% to 100%. It was found that 61.5% (8/13) of strains belonged to group A were resistant to 5 or less antibiotics, while 66.7% (24/36) of strains belonged to group D were resistant to 6 or more antibiotics. Results showed association of Trimethoprim/Sulphamethoxazole resistance with the D group and was statistically significant difference at P < 0.05. Among fluoroquinolones and/or quinolones-resistant strains, in fact, the frequencies of groups D and A, were, respectively, 75.0% (27/36) and 61.5% (8/13). Virulence genes were detected by PCR. Results showed that the prevalence of virulence genes ranged from 0% P-fimbria adhesion variant 1 (papG I) allele, and α- hemolysin (hlyA)) to 86% Type1 fimbria adhesion (fimH) and Serum resistance-associated outer membrane protein (traT) in strains tested. Virulence genes aerobactin receptor (iutA), Iron regulated A homologue adhesion (iha), Group 2 capsule synthesis gene (kpsMTII), Uropathogenic specific protein (usp), and Yersiniabactin receptor (fyuA) have the following prevalence 74%, 64%, 64%, 58% and 52%, respectively. Distribution of fimH gene was 86.1% and 84.6% in group D and A, respectively. The prevalence of genes tested in each strain was ranged from 5.6% to 83.3%. The results showed that the mean virulence scores for group D was 8.2 and ranged from 2 to15, while for group A was 6.2 and ranged from 1 to14. The mean virulence scores between the 2 groups was statically significant difference at P = 6.2 x 10-4. Also it was found that 69.2% (9/13) of strains belonged to group A carried 6 or less virulence factors, while 66.7% (24/36) of strains belonged to group D carried 7 or more virulence factors. The quinolones and/or fluoquinolones sensitive strains related to group D showed an increase in prevalence of Catecholate siderophore receptor (iron) virulence gene than resistant. In group A, average of prevalence of P-fimbria adhesion variant 2 (papGII) was increased and fimH decreased in quinolones and fluoquinolones sensitive strains. Comparison between resistant and sensitive strains to quinolones and fluoquinolones regardless to phylogenetic groups, sensitive strains showed increase in Outer membrane protease T (ompT) virulence genes. It seems that there is no single virulence factor nor virulence profile that is entirely specific to UTI. It also was 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. In conclusion, the molecular analysis of 50 E. coli urine isolates exhibited a greater prevalence of phylogenetic group D, high virulence scores and high resistance scores than group A. Urinary tract infections caused by such strains represent a clinical problem because of limited therapeutic options. Even though additional, in vivo studies by using mutant strains or the product of these genes should be performed to confirm the significance of the detected VFs. Further analysis of VF profiles with regard to specific clinical symptoms and defined severity is recommended.