Eradication of methicillin resistant S. aureus bioflm by the combined use of fosfomycin and β-chloro-L-alanine

Bioflm formation is an important virulence factor for Methicillin-resistant Staphylococcus
aureus (MRSA). Fosfomycin is a borad-spectrum antibiotic with inhibitory effects on bioflm production and β-Chloro-L-alanine (β-CLA) is an amino acid analog. The aim of this study was to determine effect of the combination of fosfomycin and
β-CLA on bioflm production by MRSA isolates. Also,the clonal relatedness of the isolates was evaluated.
Materials and Methods: To determine the ability of bioflm production by 42 MRSA isolates, microtiter plate method was
used. Antibacterial activities of fosfomycin and β-CLA were investigated by determining MICs and MBCs. Antibioflm
activities were measured in the presence of sub-MIC concentrations of fosfomycin, β-CLA or a combination of both. RAPDPCR was used for investigating the clonal relationship between isolates by the two specifc primers.
Results: 21.4% of isolates were strong and 5% were moderate bioflm producers. The effect of fosfomycin plus β-CLA
treatment on bioflm production was signifcantly different from non-treated, fosfomycin and β-CLA groups (p=0.00, 0.004
and 0.000 respectively). RAPD-PCR analysis revealed that the RAPD1 primer had more discriminatory power. The Sizes of
RAPD-PCR bands ranged from 150 bp to 1500 bp and the number of bands varied from 1 to 13.
Conclusion: Clonal relatedness of isolates showed that the majority of bioflm producing isolates had identical pattern and
only three isolates showed more than 80% similarity. The combination of fosfomycin and β-CLA could be introduced as an
excellent mixture for eradication of MRSA bioflms in vitro.