Iranian Journal of Microbiology 2017. 9(1):1-10.

Eradication of methicillin resistant S. aureus biofilm by the combined use of fosfomycin and β-chloro-L-alanine
Elham Akbari-Ayezloy, Nima Hosseini-Jazani, Saber Yousefi, Nazanin Habibi


Background and Objectives: Biofilm formation is an important virulence factor for methicillin-resistant Staphylococcus aureus (MRSA). Fosfomycin is a borad-spectrum antibiotic with inhibitory effects on biofilm 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 biofilm production by MRSA isolates. Also,the clonal relatedness of the isolates was evaluated.

Materials and Methods: To determine the ability of biofilm production by 42 MRSA isolates, microtiter plate method was used. Antibacterial activities of fosfomycin and β-CLA were investigated by determining MICs and MBCs. Antibiofilm 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 specific primers.

Results: 21.4% of isolates were strong and 5% were moderate biofilm producers. The effect of fosfomycin plus β-CLA treatment on biofilm production was significantly 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 biofilm 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 biofilms in vitro.


MRSA, Fosfomycin, Phosphomycin, β-chloro-L-alanine, Biofilm, RAPD-PCR

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