Screening of Fruit and Vegetable Salads retailed in Ago-Iwoye, Ogun State for Extended- Spectrum Beta-Lactamase Producing Gram-Negative Bacteria

Abstract

Extended-Spectrum Beta-Lactamase (ESBL) producing bacteria are of great concern to healthcare because of their
resistance to β-lactam antibiotics. This study aims to screen Gram-negative bacteria recovered from fruit and
vegetable salads for ESBL production. The bacteria in thirty samples of fruit and vegetable salads purchased from
food vendors were isolated and identified with standard microbiological methods. The Gram-negative bacteria
recovered were screened for ESBL production by the double disk synergy test (DDST) and brilliance ESBL agar
(BEA). The total coliform counts in the fruit and vegetable salads were in the ranges 2.3 - 19.1 x 104 cfu/g and 2.8
- 19.4 x 104 cfu/g respectively. Ninety-eight (98) Gram-negative bacteria were recovered from the salad samples.
They were Escherichia coli (34.7%), Citrobacter freundii (21.4%), Enterobacter cloacae (10.2%), Enterobacter
aerogenes (9.2%), Pseudomonas aeruginosa (9.2%). Klebsiella oxytoca (8.2%), Klebsiella pneumoniae (4.1%) and
Proteus mirabilis (3.1%). For ESBL production using DDST, 43. 9% (43) of the isolates were positive for the test.
On the brilliance agar, 68.4% (67) showed the expected colour change as outlined by the manufacturer. However,
five strains of K. oxytoca showed blue growth while sixteen of C. freundii had brown growth. ESBL-producing E.
coli strains that were not detected with DDST grew on BEA. This finding showed that ESBL-producing bacteria
are present in fruit and vegetable salads retail in Ago-Iwoye, hence, there is need to take the necessary precautions
during the preparation and storage of these food products to prevent contamination by these pathogens and
subsequent production of ESBL.