Scientific African (Sep 2020)
Bacteriological assessment of tropical retail fresh-cut, ready-to-eat fruits in south-western Nigeria
Abstract
Globally, more than 20 kinds of fruits are vended as minimally processed or fresh-cut fruits (FCFs). In Nigeria, pineapple (Ananas comosus) and watermelon (Citrullus lanatus) are among the commonest FCFs retailed and consumed regularly. However, the consumption of FCFs vended in open markets may constitute health risks owing to microbial contamination. This study assessed the bacteriological safety of FCFs in urban markets across six south-western Nigerian states. One hundred and twenty pineapple and watermelon products, samples of fruit wash water and vendors’ hand swabs were randomly sampled in markets and analysed for bacterial contamination by standard bacterial culturing methods, followed by analyses of partial 16S ribosomal RNA (rRNA) gene sequences. Bacterial isolates were further screened for haemolysin and amylase production, as well as subjected to antibiotic sensitivity testing against eight commonly administered antibiotics. Citrobacter, Enterobacter, Escherichia, Klebsiella, Pantoea and Shigella were the enteric bacterial genera identified in the fruits. Within these genera, 11 species were detected including two potential pathogens, Enterobacter hormaechei and Enterobacter sichuanensis, that are reported for the first time in vended FCFs in Nigeria. Klebsiella pneumoniae was detected across all sampling points and sample types, suggesting its prevalence in the FCFs process chain. About 10% of 102 isolates obtained had haemolytic potentials against erythrocytes, while 9.8% produced amylase. About 76% of the isolates were multidrug-resistant strains. Co-resistance to ampicillin and gentamicin was the most prevalent resistance pattern observed. About 7% of all isolates including those of Escherichia coli, E. hormaechei, E. sichuanensis and Shigella flexneri were resistant to all the tested antibiotics. Hand swabs from fruit vendors and fruit wash water revealed phylotypes similar to those in the FCFs, suggesting their involvement as potential sources of contamination of the fruits. Appropriate food safety measures for handlers and consumers of FCFs are thus recommended.
