الفهرس 
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Abstract
Proteus mirabilis is not only highly widespread in environment, but also is responsible for most Proteus infections, especially in human urinary tracts. P. mirabilis can cause several infections mainly urinary tract infections and wound infections. P. mirabilis pathogenicity is mediated by various virulence factors including adhesins which contribute to biofilms, flagellae that control motility and swarming, toxins for invasion and quorum-sensing that play a major role in biofilm formation. It also produces several enzymes such as urease that breaks down the urea into ammonia and carbon dioxide which increases the pH of urine causing stone formation and they also produce IgA-degrading metalloprotease.
The aim of the study was to detect different virulence factors in P. mirabilis isolates from different clinical specimens using phenotypic and genotypic methods. This study was carried out during a period of 18 months. During this period a total of 100 isolates of P. mirabilis were collected from microbiology lab of Medical Research Institute, Alexandria university.
Identification of P. mirabilis was done by conventional methods, including morphology, culture characteristics and traditional biochemical tests. Susceptibility of P. mirabilis isolates to different antibiotics was determined by Kirby-Bauer disk diffusion method according to CLSI recommendations 2021.
The majority of P. mirabilis isolates were isolated from urinary tract infections (69%) ;(including mid-stream urine (55%) and catheterized urine (14%),followed by wound infection (31%). The results of drug susceptibility tests revealed that approximately (34%) of the isolates were MDR and (5%) of them were XDR. Virulence factors such as motility, swarming activity, urease, protease, hemolysin and biofilm formation were phenotypically detected among the 100 P. mirabilis isolates. All isolates (100%) were positive to motility, swarming, urease and protease production. Whereas 90% of them were positive for hemolysis production and 73% of them were biofilm producers.
There was statistically significant difference (p=0.034) regarding biofilm among different types of clinical samples since all catheterized urine samples formed biofilm (100%),followed by wound isolates (74.2%)then mid-stream urine samples(65.5%).Number of biofilm producers (64.3%-100%) were higher than non-biofilm producers (0%-35.7%) among antibiotic resistant isolates.
Virulence genes such as flaA, ureC, zapA, hpmA, luxS, uca, mrpA and atf genes were detected among the 100 P. mirabilis isolates. All isolates (100%) possessed ureC gene and zapA gene and all of them produce Urease and protease enzymes. Among all isolates that were positive to motility and swarming, flaA gene was positive in 98% of them. The hpmA gene was detected in 90% of isolates that also showed positive hemolysis test.Biofilm related genes such as luxS, uca, mrpA and atf showed appearance rate of 99%,96%,89% and 84%, respectively.
Among biofilm producers, luxS gene was detected in all biofilm producers followed by uca gene (98.6%) then mrpA gene (91.8%), but atf gene (86.3%) was the least one of them.