Abstracto

Detection of virulence factors, phylogroups, serogroups and biofilm formation among CTX-M-1 positive Escherichia coli isolated from patients with pyelonephritis

Seyyed Khalil Shokouhi Mostafavi, Shahin Najar-Peerayeh, Ashraf Mohabbati Mobarez, Mehdi Kardoust Parizi

Objectives: Urinary tract infections are among the most frequent infections caused by Escherichia coli isolates. The aims of this study were determination of antibiotic susceptibility and detection of virulence genes, phylogroups, serogroups and biofilm formation of E. coli isolates from patients with pyelonephritis.

Methods: A total of 20 E. coli isolates were isolated from pyelonephritis. The antimicrobial susceptibility test was performed for eleven antibiotic disks. The biofilm formation assay was performed with Microtitre Tissue Plate (MTP) assay. The CTX-M1 gene and virulence genes including fimH, fyuA, traT, iutA, papII, kpsMII, ompT, ibeA, sfa, iroN, iucD, afaC, papI and papIII and also phylogroups and serogroups were detected with specific primers.

Results: In the biofilm assay, one isolate produced strong biofilm. Among virulence encoding genes, 19 (95%) isolates amplified the all fimH, fyuA and traT genes, followed by iutA (90%, n=18), papII (75%, n=17), kpsMII (60%, n=12), ompT (55%, n=11), ibeA (30%, n=6), sfa (20%, n=5), and iroN=iucD=afaC=15%, (n=3), but none for papI and papIII. The majority (50%, n=10) of E. coli isolates from pyelonephritis belonged to the phylogroup B2, followed by phylogroups D and A (each equal to 20%, n=4) and B1 (10%, n=2). Seroproups included O25 (20%, n=4), O1 (15%, n=3), O4=O18=O75 (each equal to 10%, n=2), and O2=O12=O15=O16=1 (0.05%).

Conclusion: The adhesive virulence factors play a critical role in the pathogenesis of pyelonephritis as their prevalence was high. Continued and vigilant surveillance is necessary to monitor the dissemination of antimicrobial resistance in uropathogens.