Impact of Public Health and Occurrence of Multidrug-resistant Bacteria Isolated from Lettuce (Lactuca sativa) Sold in Kpirikpiri Market, Ebonyi State, Nigeria

Abstract

Vegetables, including lettuce (Lactuca sativa), can be exposed to pathogenic microorganisms during production, transportation, handling, processing, and selling through handling by vendors and consumers. Microbial contamination of vegetables could result from the use of animal waste containing antibiotic-resistant bacteria as fertiliser to enhance plant growth. The study aimed to assess the impact on public health and the occurrence of multidrug-resistant bacteria isolated from lettuce (Lactuca sativa) sold in Kpirikpiri Market, Ebonyi State, Nigeria. Twenty (20) lettuce samples collected from Kpirikpiri Market in Ebonyi Local Government Area were analysed bacteriologically using standard microbiological procedures. The bacterial isolates were subjected to antibiotic susceptibility testing using the Kirby–Bauer method. The bacterial counts showed a total aerobic count within the range of 9.4x 10-4–1.1 x 10-4cfu/g, with a mean value of 2.96 x 10-4cfu/g. Morphological and biochemical characterisation of the isolates identified six bacterial groups (Escherichia coli, Pseudomonas species, Salmonella species, Shigella species, Staphylococcus aureus and Proteus species) were identified from the samples. The percentage occurrence of isolates showed that Staphylococcus aureus and Escherichia coli each accounted for 3 (18.75%); Proteus species accounted for 4 (25%), while Salmonella species, Shigella species, Pseudomonas species each accounted for 2 (12.5%). Antibiotic susceptibility testing showed that Pseudomonas species were 100% resistant, Proteus species and Shigella species were 90% resistant, Escherichia coli and Salmonella species were 80% resistant, while Staphylococcus aureus showed 70% resistance to the tested antibiotics. The six bacterial isolates had an average MARI value of 0.57, indicating resistance to five different classes of antibiotics. The findings suggest that lettuce may harbour potentially pathogenic bacteria with resistance to several tested antibiotics. Concerted efforts are therefore warranted to monitor the use of animal dung as fertiliser in vegetable cultivation. Furthermore, appropriate processing and improved market sanitation may help to reduce such contamination.