In Vitro Activity of Fosfomycin on Biofilm in Community-Acquired Staphylococcus Aureus Isolates

Abstract

Objective: Staphylococcus aureus is a significant pathogen microorganism that can lead to serious infections. In this study, we researched the activity of biofilm formation and fosfomycin on biofilm in community-acquired S. aureus isolates that were drawn from human noses. Methods: Microtitration plate method was used to determine biofilm formation. The effect of fosfomycin on sessile cells was studied on biofilm matrix composed around plastic beads. The icaA, icaD, icaB, icaC, bap, eno, fnbA, fnbB, clfA, clfB, fib, ebpS, cna and mecA genes were screened by Polymerase Chain Reactions (PCR). Results: S. aureus was isolated from 87 samples (13.2%) out of a total 658 nasal samples. We found that 10 of these isolates (11.4%) were methicillin-resistant S. aureus (MRSA). A total of 86 isolates had the ability to form biofilm. The biofilm inhibitor concentration (BIC) and minimum biofilm eradication concentration (MBEC) of fosfomycin were determined as 8 µg/ml and 32 µg/ml, respectively. In the molecular detection results of biofilm-related genes of these isolates, ica-dependent genes were determined to be quite high. However, no bap gene was observed to be positive in any of the isolates. Among the other genes, the most frequent genes to be declared positive were eno (97.6%) and fnbA (94.1%). Conclusion: This study indicates that prevalence of biofilm genes in S. aureus isolates in nasal flora is high and fosfomycin is an effective anti-biofilm agent alone. However, to increase fosfomycin’s efficiency, there is a need for more combination studies to make it more effective.