Mapping the Distribution Patterns of Multiple-Drug Resistances Gram-Negative Bacterial Strains Recoverable From Food and Environmental Samples in Kibera Informal Settlements

Abstract

In 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.