Growth Potential of Salmonella Typhi in Nigeria’s “Swallow” Solid Foods and Sources of their Contamination by Salmonella and Coliform Bacteria in Eateries

The growth potential of Salmonella serovar Typhi was investigated in four popular Nigeria's cassava (Manihot esculenta)- and yam (Dioscorea rotundata)-based solid foods (amala, akpu/fufu, eba and pounded yam) commonly referred to as “swallow”. Growth curves in the sterilised four “swallows” obtained from eateries tended to be identical while the growth rates marginally varied (0.25-0.37 log cfu/g/h), but was lower than in chicken meat (0.40 log cfu/g/h) used for comparison. Coliforms and Salmonella were isolated from contact surfaces of swallow food processing materials (mortars, pestles wooden spoon, electric pounder and nylon wrappers) using McConkey and Brilliant Green media with median counts lower in normal than makeshift eateries (coliform, 0.00-0.84 vs 1.50-1.70 log cfu/cm2; Salmonella, 0.00-0.30 vs 0.30-0.60 log cfu/cm2). Prevalence of eateries with coliform- and Salmonella-contaminated ready-to-eat swallow foods was 8.7-30.4% in normal eateries and 23.2-46.4% in makeshift eateries. Hygienic practices were generally low (<50% of maximum points) although the normal eateries were associated with good hygienic practice (OR, 1.64; 95% CL, 0.75-3.20; P<0.05). It can be concluded that S. typhi can grow in swallow foods, and that contact surfaces of processing materials are potential sources of bacterial contaminants during preparation of swallow foods especially in the commonly patronised makeshift eateries.