Investigation of biofilm formation in methicillin resistant Staphylococcus aureus isolates by genotypic and phenotypic methods and effect of vancomycin and teicoplanin on biofilm inhibition

The pathogenicity factors of Staphylococcus aureus include biofilm production. In this study, the biofilm production abilities of methicillin-resistant S. aureus (MRSA) strains were investigated using genotypic and phenotypic methods. Additionally, the effect of glycopeptides on biofilm was examined. This study included 130 MRSA isolates. Biofilm was detected by the microtiter plate method. The minimum inhibitory concentration (MIC) of glycopeptides was evaluated through the broth microdilution method. The biofilm inhibitor concentration (BIC) values were investigated in isolates with strong biofilm production. The mecA (methicillin resistance gene), icaA, and icaD (biofilm-associated genes) were amplified by polymerase chain reaction techniques. Eighty-one isolates (62.31%) formed biofilms, while thirty isolates (23.08%) exhibited strong biofilm formation. Thirty isolates had higher BIC90 values than MIC₉₀ values. The mecA gene was confirmed in 125 (96.15%) isolates, the icaA gene in 96 (73.85%) isolates, and the icaD gene in 100 (76.92%) isolates. There was statistical significance between ica genes and the biofilm produced (p<0.05). In conclusion, increased biofilm formation due to the effect of ica genes increases the concentration values at which antibiotics act.