Prevalence, Antibiotic Resistance, and Biofilm Formation of Proteus mirabilis in Dairy Products: Implications for Veterinary and Public Health.

Abstract

Dairy products are essential components of human and animal nutrition, providing vital nutrients such as proteins, vitamins and minerals. However, their susceptibility to microbial contamination, particularly by pathogens like Proteus mirabilis, poses significant risks to both animal and public health. This study investigated the prevalence, antibiotic resistance patterns and biofilm-forming ability of P. mirabilis in various dairy products, with a focus on raw milk, in Shahrekord, Iran. A total of 480 samples, including raw cow, goat and sheep milk, as well as cheese, yogurt, cream, curd and a traditional Iranian fermented yogurt-based beverage (doogh), were analysed under controlled laboratory conditions. The findings revealed a 12.29% prevalence rate of P. mirabilis, with raw cow's milk showing the highest contamination rate (21.66%). Among the isolates, 88.12% were capable of forming biofilms, and 71.15% exhibited strong biofilm production. Antibiotic susceptibility testing identified a high prevalence of multidrug-resistant strains, with the highest resistance rates observed for cotrimoxazole (59.32%) and gentamicin (50.84%). In addition, 25.42% of the isolates were identified as extended-spectrum beta-lactamase (ESBL) producers, with blaCTX-M being the most prevalent resistance gene. A significant correlation was found between biofilm-forming ability and the presence of antibiotic resistance genes, highlighting the dual challenges of microbial persistence and antimicrobial resistance. These findings emphasize the need for improved hygiene practices in dairy production, targeted biofilm-disrupting strategies and enhanced surveillance programs to mitigate risks to both animal and public health. This study provides critical insights for veterinary professionals and policymakers to develop effective interventions aimed at reducing contamination and combating antimicrobial resistance in dairy products.