Assessment of Bacterial and Fungal Pathogens Associated with Kola Nuts and their Public Health Significance

Kola nut (Cola nitida) is one of the economically and culturally important tree crops in Nigeria and is often traded in open-air markets where microbial contamination may be possible. In this study, the bacterial and fungal pathogens associated with apparently healthy and visibly deteriorated kola nuts purchased from six markets in Ibadan, Oyo State (Bodija, Oje, Oja Oba, Sango, Aleshinloye and Agbeni) were evaluated. A total of 150 samples (90 healthy and 60 deteriorated) were processed using standard culture, biochemical and molecular identification techniques. Antibiotic susceptibility testing and mycotoxin screening of isolates of public health concern were performed. Deteriorated nuts had a significantly greater bacterial and fungal load than healthy nuts in all markets, and there was more recovery of E. coli, Salmonella spp., S. aureus and toxigenic Aspergillus spp. from deteriorated nuts. A significant number of the Gram-negative isolates were resistant to frequently used antibiotics, and a percentage of both the Aspergillus and Fusarium positives exceeded regulatory limits for aflatoxin and fumonisin contamination. If these results are validated with real laboratory results, the results will help to conduct routine monitoring of the microbial and mycotoxin presence of kola nuts in Nigerian markets and provide recommendations for food safety measures for kola vendors and consumers.