Effect of Post Treatment with Brine and Steam on Phenotypic Resistant <i>Salmonella</i> Isolates from <i>Pentaclethra macrophylla</i>

Abstract

Food contaminated with antibiotic resistant bacteria pathogens is a major threat to public health. Apart from infecting man they serve as reservoirs of genes for antimicrobial resistance and they easily transfer the resistant genes to both related and unrelated bacterial species; hence the aim of the present study. The prevalence, antibiotic sensitivity pattern and plasmid profile of Salmonella spp isolates from ready-to-eat ugba (Pentaclethra macrophylla) samples vended in various markets in Enugu State, Nigeria was investigated. The samples were further examined to determine the effect of post treatment with brine and steam respectively. A total of 40ugba (P. macrophylla) samples were obtained from different food vendors in the selected markets in Enugu metropolis, Enugu state, Nigeria. Cultures were done on Salmonella-shigella agar and characterized by standard microbiological methods. Post treatment with brine involved rinsing 5g of P. macrophyla samples in three changes of brine solution while post treatment using steam was done by boiling5g of P. macrophyla samples for 10 mins to an internal temperature of 30°C, 60°C, 75°C and 90°C and subsequently cultured on Salmonella-Shigella agar by pour plate method. Antibiogram of the isolates were determined by using disc diffusion method and plasmid DNA was extracted using plasmid alkaline lysis method and separated by agarose gel electrophoresis. Salmonella spp. was recorded at high prevalence of 95%. The isolates showed varied resistance to different antibiotics; amoxicillin (50%), augmentin (100%), streptomycin (61%), septin (95%), gentamycin (45%) and chloramphenicol (68%). Multiple antibiotic resistant was observed in 26% of the isolates. Agarose gel electrophoresis showed that all the ten selected isolates had single plasmid bands of 20kb size. The results revealed relative similarities between the Salmonella isolates but possibility of five clones among the Salmonella isolates. At p<0.05 steam reduced the microbial load of isolates in P. macrophyla than in brine. The results from this study show that Salmonella spp. contamination of P. macrophyla was high in the study area and isolates were multidrug resistant; therefore food handlers should be properly educated and monitored to ensure compliance to proper food hygiene guidelines and P. macrophyla should be steamed prior to consumption to reduce the rate of infection.