Background Proteus mirabilis (P. mirabilis) is a leading cause of urinary tract infections (UTIs) in both community and healthcare settings, especially in catheterized patients. Proteus species express various types of fimbriae that can serve as colonization-related virulence factors. The severity of infection escalates when these virulent strains acquire antibiotic resistance. The aim of this study was to investigate the prevalence, antimicrobial susceptibility, and genetic determinants of fluoroquinolone resistance in P. mirabilis isolates. Further, to screen for the presence of virulence genes encoding fimbriae and integrons. Methods A total of 103 P. mirabilis isolates were recovered from urine samples collected from catheterized and non-catheterized UTI patients at Minia University Hospitals, Egypt. Antimicrobial susceptibility of fluoroquinolone-resistant (FQR) isolates was evaluated using the disc diffusion method. Phenotypic detection of extended-spectrum β-lactamase (ESBL) production was then performed, followed by molecular analysis for ESBL and plasmid-mediated quinolone resistance (PMQR) genes within the FQR isolates. All P. mirabilis isolates were screened by PCR for four virulence genes encoding fimbriae. Additionally, class 1, 2, and 3 integrons were investigated. Results Among the 103 P. mirabilis isolates, 47 (45.6%) were non-susceptible to ciprofloxacin, of which 22 exhibited intermediate non-susceptibility and 25 were resistant. Multidrug resistance (MDR) was found in 70.2% (33/47) of FQR isolates, with significantly higher resistance to amoxicillin-clavulanic acid, sulfamethoxazole-trimethoprim, gentamicin, and amikacin compared to fluoroquinolone susceptible isolates. The virulence genes pmfA and mrpA were detected in 86.4% (89/103) and 78.6% (81/103) of isolates, respectively, while both atfA and ucaA were present in 70.9%. Isolates from catheterized patients showed significantly higher prevalence of virulence genes compared to those from non-catheterized individuals. PMQR genes were detected in 91.5% (43/47) of FQR isolates. The most prevalent were qnrS (74.5%), aac(6′)-Ib-cr and qnrA (66% each), followed by qnrC (42.6%), qnrB (31.9%), and qepA (8.5%). Co-carriage of multiple PMQR genes was significantly more frequent in isolates with ciprofloxacin resistance than in those with intermediate non-susceptible (p = 0.0001). ESBL genes were detected in 36.8% of ESBL-producing FQR isolates, with blaTEM being the most prevalent (26.3%), followed by blaCTX−M−9 (21.1%), while blaSHV was not detected. Among the 103 P. mirabilis isolates, 99 (96.1%) carried class 1 and/or class 2 integrons, while none harbored class 3 integrons. Conclusion Our findings reveal a significantly high prevalence of fimbriae-associated virulence genes in P. mirabilis isolates from catheterized UTI inpatients, alongside notable dissemination of PMQR genes and class 1 integrons. The coexistence of these virulence and resistance determinants, particularly in hospital-derived strains, is concerning, as it may enhance horizontal gene transfer. This combination contributes significantly to MDR strain persistence and dissemination in the clinical settings.

Assessment of genetic determinants of virulence and fluoroquinolone resistance in Proteus mirabilis isolates from urinary tract infections in Egypt

期刊论文
出版模式：

开放获取
发表日期：

2026年7月7日

查看全文

Dalia N. Kotb,
Shaimaa Zaki,
Soha S. Abdelrahim

摘要

Background

Proteus mirabilis (P. mirabilis) is a leading cause of urinary tract infections (UTIs) in both community and healthcare settings, especially in catheterized patients. Proteus species express various types of fimbriae that can serve as colonization-related virulence factors. The severity of infection escalates when these virulent strains acquire antibiotic resistance. The aim of this study was to investigate the prevalence, antimicrobial susceptibility, and genetic determinants of fluoroquinolone resistance in P. mirabilis isolates. Further, to screen for the presence of virulence genes encoding fimbriae and integrons.

Methods

A total of 103 P. mirabilis isolates were recovered from urine samples collected from catheterized and non-catheterized UTI patients at Minia University Hospitals, Egypt. Antimicrobial susceptibility of fluoroquinolone-resistant (FQR) isolates was evaluated using the disc diffusion method. Phenotypic detection of extended-spectrum β-lactamase (ESBL) production was then performed, followed by molecular analysis for ESBL and plasmid-mediated quinolone resistance (PMQR) genes within the FQR isolates. All P. mirabilis isolates were screened by PCR for four virulence genes encoding fimbriae. Additionally, class 1, 2, and 3 integrons were investigated.

Results

Among the 103 P. mirabilis isolates, 47 (45.6%) were non-susceptible to ciprofloxacin, of which 22 exhibited intermediate non-susceptibility and 25 were resistant. Multidrug resistance (MDR) was found in 70.2% (33/47) of FQR isolates, with significantly higher resistance to amoxicillin-clavulanic acid, sulfamethoxazole-trimethoprim, gentamicin, and amikacin compared to fluoroquinolone susceptible isolates. The virulence genes pmfA and mrpA were detected in 86.4% (89/103) and 78.6% (81/103) of isolates, respectively, while both atfA and ucaA were present in 70.9%. Isolates from catheterized patients showed significantly higher prevalence of virulence genes compared to those from non-catheterized individuals. PMQR genes were detected in 91.5% (43/47) of FQR isolates. The most prevalent were qnrS (74.5%), aac(6′)-Ib-cr and qnrA (66% each), followed by qnrC (42.6%), qnrB (31.9%), and qepA (8.5%). Co-carriage of multiple PMQR genes was significantly more frequent in isolates with ciprofloxacin resistance than in those with intermediate non-susceptible (p = 0.0001). ESBL genes were detected in 36.8% of ESBL-producing FQR isolates, with bla_TEM being the most prevalent (26.3%), followed by bla_CTX−M−9 (21.1%), while bla_SHV was not detected. Among the 103 P. mirabilis isolates, 99 (96.1%) carried class 1 and/or class 2 integrons, while none harbored class 3 integrons.

Conclusion

Our findings reveal a significantly high prevalence of fimbriae-associated virulence genes in P. mirabilis isolates from catheterized UTI inpatients, alongside notable dissemination of PMQR genes and class 1 integrons. The coexistence of these virulence and resistance determinants, particularly in hospital-derived strains, is concerning, as it may enhance horizontal gene transfer. This combination contributes significantly to MDR strain persistence and dissemination in the clinical settings.