Isolation of Staphylococcus epidermidis from milk of mastiticcows and determination of biofilm formation ability

Objective: The aim of this study is to determine the biofilm-forming ability of Staphylococcus epidermidis strains isolated from mastitic milk samples using phenotypic and genotypic methods. The results are intended to be evaluated in terms of mastitis management and the prevention of treatment-resistant infections in dairy cattle farms. Materials and Methods: The research was conducted in October 2024 with milk samples collected from 150 lactating cows in various farms in Aydın province and surrounding areas. Blood Agar was used for isolation, and Congo Red Agar (CRA) was used for biofilm detection. Preliminary identification was carried out by Gram staining, catalase and coagulase tests, and species confirmation was performed using the VITEK 2 automated system. Biofilm production was evaluated phenotypically based on colony morphology on CRA, and genotypically through PCR detection of icaA and icaD genes. Results: Staphylococcal bacteria were isolated from the milk samples, and their catalase and coagulase positivity was confirmed. Phenotypic biofilm tests on CRA revealed positive biofilm formation in some strains. Genotypic analyses showed that icaA and icaD genes were present in some biofilm-positive and biofilm-negative isolates, indicating partial concordance between phenotypic and genotypic findings. Conclusion: This study demonstrates that S. epidermidis strains isolated from mastitic milk possess biofilm-forming potential. Combined evaluation of phenotypic and genotypic tests provides a more reliable detection of biofilm presence. The findings are significant for improving control and treatment strategies against mastitis pathogens.