Prevalence of virulence genes in biofilm producing uropathogenic Proteus mirabilis strains isolated from patients with urinary tract infection in Isfahan during 2022

Proteus mirabilis is the main pathogen causing complicated urinary tract infections (UTIs), especially catheter-associated UTIs (CAUTIs), which efficiently forms crystalline biofilm on different surfaces such as urethral indwelling catheters. The pathogenesis of P. mirabilis is related to its ability to produce a variety of virulence factors, such as biofilms, adhesion molecules, urease, hemolysin, swarming activity, proteases and siderophores. The aim of this study was to characterize the frequency of different virulence genes among biofilm producing uropathogenic P. mirabilis strains isolated from patients with UTI in a referral hospital in Isfahan during April-December 2022.

In this study a total of 50 P. mirabilis isolates were collected from urine samples of 50 patients with UTI in a referral hospital in Isfahan and confirmed using polymerase chain reaction (PCR) by specific primers for ureC and ureR genes. All strains were tested for their ability to form biofilm using quantitative microtiter plate (MTP) assay, and the frequency of different virulence associated genes (zapA, zapD, pta, hpmA, mrpA and hlyA) among biofilm producing strains was determined by specific primers.

All collected isolates were positive for ureC and ureR genes and confirmed as P. mirabilis. Also, all strains were able to form biofilm, in which 52, 44 and 4% of strains produced strong, moderate and weak biofilm, respectively. Moreover, zapA and zapD genes were detected in 100% of biofilm positive strains and the frequency of hpmA, pta and mrpA genes was limited to 96, 94 and 90% of strains. On the other hand, the hlyA gene was not detected in any studied P. mirabilis strains.

The high prevalence of biofilm producing P. mirabilis with a broad spectrum of virulence factors among patients with UTI in the studied hospital in Isfahan, indicating the clonal dissemination of biofilm producing pathogenic strains in Isfahan also the importance of P. mirabilis strains as a potential threat to patients’ health.