Mountain Top University Library

ABSTRACT
Fresh produce constitutes a necessary part of the human diet, it provides essential vitamins,
minerals, and fiber. However, the rising consumption of fresh produce has added to an elevated
number of illness outbreaks around the world. Fresh produces are often consumed uncooked,
therefore; there is increased risk if contaminated with pathogenic microorganisms like E. coli
O157:H7 causing foodborne illness and in extreme cases death especially in children. In
developing countries like Nigeria, fresh produce is purchased both in closed stores and road
side open kiosk and on most occasions are not processed hygienically. This study evaluated
the prevalence of Shiga toxin producing E. coli in varieties of fresh produce (Lettuce, Water
Melon, Pineapple, Cucumber, Cabbage, Carrot and Pawpaw) from various roadside fruit
vendors at different locations around the South-west region of Nigeria precisely Lagos and
Ogun state. A total of 64 samples were tested for presence of E. coli using Sorbitol MacConkey
Agar and MacConkey Agar plates. All samples had presumptive STEC, molecular
identification of selected isolates (n = 21) for STEC virulence genes (stx1 stx2 and eae) using
multiplex PCR was done. The total viable count (TVC) for presumptive STEC in the samples
was in the range of 4.5 to 7.8 log10cfu/g. Lettuce from Ibafo had the highest total viable count.
Using Multiplex PCR, stx1 gene was detected in some of the isolates which confirmed the
presence of STEC in the fresh produce. The prevalence of STEC among the isolates (n = 21)
was 4.8%. The presence of STEC and a very high microbial count of presumptive STEC poses
a threat to public health which could lead to foodborne illnesses including hemorrhagic colitis
(HC) or hemolytic uremic syndrome (HUS).
Key words: STEC, fresh produce, food borne disease, virulence gene, HUS.