A Simplified Scheme for Efficient Isolation and Identification of MRSA from Seafood and Aquatic Environment

Abstract

Methicillin resistant Staphylococcus aureus (MRSA) is a versatile pathogen causing numerous clinical illnesses and a potentially important organism of food borne disease outbreaks. This pathogen has increasingly been detected in several foods including the seafood. However, protocol for efficient isolation and identification in fisheries sector is not developed, which is an environment at elevated salt concentration. Therefore, experiments with 5 enrichment broths and four selective agar plates in different permutations and combinations were tested for improved recovery of MRSA from seafood of retail fish markets, fish landing centers and aquaculture farms. This isolation and identification scheme has been assessed for over 250 samples from the fisheries sector and the results suggested that this is the very simplified procedure for efficient isolation and identification of MRSA and can be accomplished in shortest period of time and as a routine laboratory protocol. This may be adopted in other food sectors after validation. The protocol describes that samples enriched in tryptic soy broth supplemented with 10% salt and 1% sodium pyruvate followed by selective plating in BD ChromAgar MRSA II showed improved isolation of MRSA compared to Oxacillin Resistance Screening Agar Base ORSAB, Baird Parker Agar (BPA) + OX.The protocol also describes the further simplified steps of phenotypic and molecular confirmation of MRSA in shortest period of time.