Proteus mirabilis: Insights into biofilm formation, virulence mechanisms, and novel therapeutic strategies

Proteus mirabilis , a gram-negative bacterium, is a significant cause of catheter-associated urinary tract infections, bacteremia, and other serious health complications. Its pathogenicity is driven by several virulence factors, including swarming motility, urease production, fimbriae, hemolysins, and the ability to form biofilms. These features enable the bacterium to colonize host tissues, evade immune responses, and resist antimicrobial treatments. For instance, urease increases urine alkalinity, promoting the formation of crystalline biofilms and struvite stones, which further complicates infections. Biofilm formation provides a shield against antibiotics, rendering infections persistent and difficult to treat. The increasing resistance of P. mirabilis to antibiotics highlights an urgent need for innovative therapeutic approaches. Ciprofloxacin, a commonly used antibiotic, significantly reduces 33–55 % of the biofilm’s biomass. Complementary strategies, including the use of phytochemicals and nanoparticles (NPs), have emerged as promising alternatives. Phytochemicals, such as allicin and curcumin, target specific virulence factors, whereas nanoparticles reduce biomass up to 53.4 %. Lactobacilli spp., such as L. gasseri produce lactic acid, which inhibits growth and prevents the formation of urinary stones caused by P. mirabilis . Additionally, phage therapy offers targeted solutions that combine phage vB PmiS-TH with ampicillin, causing removal of the biofilm after 24 h and preventing urinary tract infections. Targeted therapies addressing virulence factors, combined with traditional and novel antimicrobial strategies, have the potential to improve patient outcomes, particularly those vulnerable to severe complications, such as the elderly and immunocompromised individuals.