Abstract:
n this cross-sectional study conducted in Kibera informal settlements in the west
side on Nairobi, ready-to-eat food samples that consisted of kales, cabbage, Managu,
rice, ndengu, githeri, beans, meat, omena(a preparation of Rastrineobola argetea)
and ugali were analyzed to determine the diversity of Gram-negative bacteria and
contamination levels. Sewage, sludge and soil samples collected within a 10 meters
radius of the sampled food vending points were also collected and analyzed. Analysis
of contamination levels detected microbial contamination levels exceeding 104
CFU/mL in 106 (38%) of the 281 ready-to-eat foods analyzed. The burden of
contamination of these foods ranged from a mean of 4.0 × 104 to 2.3 × 106 CFU/mL,
which is above the recommended minimum threshold of 1.0 × 102 CFU/mL
considered fit for human consumption. Among these foods, vegetables, especially
kales, were the most contaminated foods with a mean of 2.3×106 CFU/mL, followed
by meats at 1.0×106 CFU/mL, while omena (a type of tiny fish) had a mean CFU/mL
of 4.0×104
. Statistical analysis revealed a significant difference in contamination
levels among foods sold near sewage, toilet, open space vending point layout, and
near dumping from those not close to these features (P 0.0001)). Sites that did not
have a clean water supply were found to have more contaminated foods exceeding
the recommended threshold for human consumption than those with a constant
supply of treated municipal water (P: 0.0001, C.I: 5.23 – 5.35, O.R: 5.28). The study
recovered seven types of non-fastidious bacteria species in these foods and these
included were; Klebsiella (29%), Escherichia coli (26%), Enterobacter agglomerans
(22%), Salmonella spp (7%), Proteus mirabilis (7%), Citrobacter freundii (7%) and
Serratia marcesence (3%). A total of 14 bacteria genera were also recovered from
sewage, sludge and soil samples; E. coli (21%), Klebsiella spp (20%), Enterobacter
spp (19%), Citrobacter spp (8%), P. aeruginosa (8%), Proteus spp (4%), Salmonella
(5%), Shigella (3%), M. morganii (3%), Edwardisella spp (2%), Hafnia spp (2%), S.
marcesence (1%), and A. baumannii (1%). On average, Ampicillin, trimethoprim and
sulfamethoxazole were the most resisted antimicrobial agents in both food and
environmental isolates, while Imipenem, cefepime, ciprofloxacin and ceftazidime
were the most effective. Class 1 integron (intI1) was more prevalent than intI2
among the screened isolates. This study's cluster analysis suggested possible
microbial contamination of ready-to-eat foods from Kibera's immediate vending
environment.
