Occurrence and Characterisation of Coagulase-Negative Staphylococci from Nigerian Traditional Fermented Foods

Abstract

Coagulase-negative staphylococci (CoNS) were believed to be avirulent although recent studies have implicated them as causative agents of diseases. The lack of standardization and poor personal hygiene in the production of traditional fermented foods may introduce these organisms into food. This study was designed to investigate the occurrence of CoNS in Nigerian traditional fermented foods. In this study, the occurrence of CoNS in a total of 324 fermented food samples comprising of six traditional fermented food samples namely ogi, iru, nono, wara, kindirmo, kunu from North Central Nigeria was investigated. CoNS were isolated from the fermented food samples employing serial dilution technique and plating out on Mannitol salt agar (Oxoid, Germany). The identification of pure isolates was carried out using standard methods for phenotypic characterisation and genotypically characterised by PCR and 16S rRNA sequencing employing the primers; MSQ-F (5′- TGA AGA GTT TGA TCA TGG CTC AG-3′) and MSQ-R (5′-ACC GCG GCT GCT GGC AC-3′). A total of 255 (79.3%) CoNS were isolated and identified. The isolates were identified as S. epidermidis, S. xylosus, S. simulans, S. kloosii and S. caprae showing 90-95% homology with reference strains from NCBI database.  S. epidermidis (50%) was the highest occurring CoNS species in the food samples examined. S. epidermidis (30.5%) was predominant in iru, S. kloosii (28.6%), S. simulans (32%) and S. xylosus (33.3%) were the highest occurring CoNS species in kindirmo and S. caprae (38.5%) was predominant in nono samples. This study established the occurrence of CoNS in Nigerian traditional fermented foods. Personal hygiene especially by food handlers and producers should be encouraged. The education on food safety should be taught to local traditional food producers and legal actions taken against non-compliance to food safety standards. Milk produced locally should be pasteurized or heat treated before use in food production.

Keywords: 16S rRNA sequencing, Characterization, Nigerian fermented foods, Coagulase-negative   staphylococci, Occurrence, Food safety.