Biofilm Formation, Virulence-Associated Genes, and Antimicrobial Resistance in Proteus mirabilis Isolates from Urinary Tract Infections in Iran

Mehdi Choori; Fateh Rahimi; Ali Qasemi; Mohammad Katouli

doi:10.3390/microorganisms14061242

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Biofilm Formation, Virulence-Associated Genes, and Antimicrobial Resistance in Proteus mirabilis Isolates from Urinary Tract Infections in Iran

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Biofilm Formation, Virulence-Associated Genes, and Antimicrobial Resistance in Proteus mirabilis Isolates from Urinary Tract Infections in Iran

Mehdi Choori, Fateh Rahimi, Ali Qasemi and Mohammad Katouli

Microorganisms, Vol.14(6), pp.1-19

2026

DOI: https://doi.org/10.3390/microorganisms14061242

PMCID: PMC13304133

PMID: 42354866

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Abstract

Proteus mirabilis

urinary tract infection

biofilm formation

antimicrobial resistance

ERIC-PCR

virulence factors

Proteus mirabilis is a frequent cause of complicated urinary tract infections (UTIs), in which biofilm formation and antimicrobial resistance contribute to persistence and therapeutic failure. This study investigated the biofilm-forming capacity, antimicrobial resistance profiles, virulence-associated genes, and genetic diversity of P. mirabilis isolates recovered from UTI patients in Isfahan, Iran. A total of 104 non-duplicate clinical isolates were analyzed. Biofilm formation was quantified using a microtiter plate crystal violet assay, and antimicrobial susceptibility testing was performed according to CLSI guidelines. Extended-spectrum beta-lactamase (ESBL) production and extended-spectrum cephalosporin resistance (ESCR) were assessed phenotypically and by PCR. Selected virulence- and biofilm-associated genes were detected by PCR, and clonal relatedness was evaluated using ERIC-PCR. Most isolates were capable of biofilm formation, with 51% classified as strong and 45.2% as moderate producers. High carriage rates of virulence- and biofilm-associated genes, including zapA, zapD, ureC, ureR, luxS, rsbA, and acrA, were observed. ESBL production and ESCR phenotypes were detected in 6.7% and 12.5% of isolates, respectively, while multidrug resistance was observed in 30.4% of isolates. ERIC-PCR analysis identified predominant clonal clusters among isolates exhibiting strong biofilm production. These findings highlight the coexistence of biofilm formation, virulence determinants, antimicrobial resistance, and clonal diversity in uropathogenic P. mirabilis in this region.

Details

Title: Biofilm Formation, Virulence-Associated Genes, and Antimicrobial Resistance in Proteus mirabilis Isolates from Urinary Tract Infections in Iran
Authors: Mehdi Choori - University of Isfahan
Fateh Rahimi - University of Isfahan
Ali Qasemi - University of Sistan and Baluchestan
Mohammad Katouli (Corresponding Author) - University of the Sunshine Coast
Publication details: Microorganisms, Vol.14(6), pp.1-19
Publisher: MDPI AG
Date published: 2026
DOI: 10.3390/microorganisms14061242
ISSN: 2076-2607
PMID: 42354866; PMC13304133
Copyright note: © 2026 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.
Data Availability: The original contributions presented in this study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author.
Grant note: This work was supported by a grant from the Office of the Vice-Chancellor for Research and Technology, University of Isfahan, Isfahan, Iran.
Organisation Unit: School of Science, Technology and Engineering
Language: English
Record Identifier: 991246278702621
Output Type: Journal article

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