MOLECULAR IDENTIFICATION AND ANTIMICROBIAL SENSITIVITY PROFILE OF BACTERIA FROM FOOD HANDLERS IN AKURE, NIGERIA

Abstract

This research work was aimed at isolating and identifying bacteria associated with food handlers in Akure metropolis using molecular and conventional methods, and also comparing the antibacterial efficacy of selected medicinal plants and conventional antibiotics against the bacterial isolates. Hand washing and hand swab samples culminating to a total of 477 samples were collected from different food vending locations in Akure. Bacteria were isolated and identified, after which the sensitivity patterns of the isolates to standard antibiotics and plant extracts were determined using disc diffusion agar and well diffusion methods, respectively. The bacterial isolates are Alcaligenes faecalis, Bacillus cereus, Bacillus subtilis, Citrobacter freundii, Enterobacter aerogenes, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Micrococcus luteus, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella enteritica, Salmonella typhi, Serratia marcescens, Shigella sonnei, Staphylococcus epidermidis, Staphylococcus aureus and, Streptococcus pyogenes. Staphylococcus aureus was observed to be the most prominent bacteria harboured by the food handlers.The isolated bacteria were subjected to 16s rRNA polymerase chain reaction, DNA gene extraction and sequence blasting using the amplified length of 1500 base pair. The sequence obtained was blasted in National Centre for Biotechnology Information (NCBI) database. Based on the 16s rRNA sequences, the following bacteria were confirmed; Escherichia coli str. K12 substr. DH10B, Klebsiella pneumoniae strain J1, Proteus mirabilis strain HI4320, Pseudomonas fluorescens SBW25, Salmonella enterica subsp.enterica serovar Typhi str. CT18, Salmonella enterica subsp. enterica serovar Infantis, Shigella flexneri 2a str. 2457T and Staphylococcus cohnii subsp. cohnii strain 532 Contig16. Phylogeny was employed in the phylogenetic tree construction due to its robustness, reliability and less-laboriousness. The result of the sequence was aligned and the phylogenetic tree constructed shows the evolutionary relationship between eight bacterial species. Two clusters were generated; Salmonella enterica subsp.enterica serovar Typhi, Salmoenella typhi LN854584.1 Staphylococcus cohnii, and Staphylococcus aureus are in cluster 1, Proteus mirabilis NC0100554.1, Bacillus thuringiensis KY652120.1 and Bacillus subtilis MG231261.1 are in cluster 2. However, bacteria in the same cluster were observed to have different phenotypic characteristics. The antibacterial efficacy of the selected medicinal plant extracts (Ocimum gratissimum and Annona muricata) were compared to that of standard antibiotics (Ciprofloxacin, Nitrofurantoin, Ampliclox, and Chloramphenicol) using three different solvents (methanol , water and petroleum ether) at 50 mg/ml, 100 mg/ml, 200mg/ml and 300mg/ml concentrations. Bioactive characterization of the selected plants revealed the presence of various active components such as Thymol, Eugenol, Caryophyllene, Gamma-terpinene, 8-methyl-4-vanillyl-7-nonenamide, N-4-Hydroxy-3-methoxybenyl 8methyldec 6 enamide, DL-6, 8-tio acidamide and N-4-Hydroxy-3-methoxyphenyl methyl nonanamide. Phytochemical analysis of the plants affirmed the presence of Tannins, Alkaloids, Flavonoids, Anthraquinone and Saponins in O. gratissimum and A. muricata. It can be deduced from this study that food handlers play a major role in the transfer of bacterial contaminants to the edible food. Also the metabolites present in O. gratissimum and A. muricata render these plants cost effective alternative source of therapy to food borne illnesses.