The Incidence of Extended-Spectrum Beta-Lactamase (ESBL)-Producing Bacteria in Salad Vegetables in Ondo City, Nigeria

Aim: This study was carried out to determine the occurrence of extended-spectrum beta-lactamase (ESBL) producing bacteria in salad vegetables in Ondo City, Nigeria.

Study Design: An experimental study design with randomized sampling.

Place and Duration of the Study: The research was carried out in the Department of Biological Sciences of Wesley University, Ondo State, Nigeria.

Methodology: Samples of cucumber, carrot, green pea, green beans, sweet corn and cabbage were analysed on appropriate agar medium. Pure isolates were identified by biochemical tests and confirmation was done by the use of API 20 E and API 20 NE in accordance with standard procedures. ESBLs screening was carried out using the double disk synergy test. Data were statistically analyzed using MedCalc statistical software (version 17.2).

Results: Total viable bacterial counts (TVBCs) ranged from 1.1 × 103 to 7.1 x 105 cfu/ml; total coliform counts (TCC) ranged from 1.2 x 102 to 3.9 x 103 cfu/ml while total faecal counts (TFC) ranged from 0 to 2.9 × 102 cfu/ml. There were statistical differences in mean TVBCs of the samples (P < 0.05). The mean TCCs of cabbage, carrot and cucumber showed no statistical significance; green beans, green pea and sweet corn also showed no statistical significance (P > 0.05). One hundred and sixty (166) isolates obtained from the samples were identified as Bacillus cereus, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Morganella morganii, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus, Serratia marcesens and Staphylococcus saprophyticus. At least one member of all bacterial species, except S. saprophyticus, produced ESBL.

Conclusion: This study revealed that salad vegetables could be a vehicle for the spread of extended-spectrum beta-lactamase-producing bacteria which translates to a threat to public health around the world as salads are loved and consumed by all categories of people globally.