Risk assessment for the occurrence of Escherichia coli 0157:H7 in indigenous fermented milk (Lee Naga a Agbora) produced in Uganda

Different types of indigenous fermented milks are widely consumed in pastoralist communities of Africa, including Uganda. Local processing of milk generally takes place under uncontrolled hygienic conditions. Lee naga a agbora, a locally fermented milk product in northern Uganda, was evaluated for microbial contamination. The changes in pH, Total Plate Counts (TPC), Total Coliforms (TC), yeasts and moulds, and Escherichia coli 0157:H7, particularly its survival during different stages of  fermentation were studied. The pH was found to decrease with fermentation time (6.54 to 4.54). E. coli was detected in most samples of Lee naga a agbora and its occurrence was observed throughout the fermentation period. The mean value of TPC (6.60± 0.10 log cfu ml-1) at the start of fermentation was significantly different (p0.05) between 48 and 72 hours. The rate of decrease in TC counts in the initial fermentation period (0 to 48 hours) was lower than the later stages of fermentation (48 to 144 hours). Yeast and mould counts increased with fermentation time (6.20 to 7.42 log cfu ml-1). On the whole, there is risk associated with consumption of Lee naga a agbora given the occurrence of E. Coli

AMERICAN JOURNAL OF FOOD AND NUTRITION Occurrence of Escherichia coli and Salmonella spp. in street-vended foods and general hygienic and trading practices in Nakawa Division, Uganda

ABSTRACT Food borne diseases such as Salmonellosis and entero-haemorrhagic Escherichia coli (EHEC) have been associated with consumption of street-vended foods in many African countries. Although health problems associated with consumption of street-vended foods do exist in Uganda, up to this day, there is limited scientific data on the microbiological quality and safety of street-vended foods in various regions of the country. The aim of this study was to establish the occurrence of common food-poisoning pathogens including E. coli and Salmonella spp. in selected street-vended foods sold in Nakawa and Naguru Parishes located in peri-urban Kampala city. Samples analyzed in the present study were based on four food categories which comprised of mainly high risk foods and those prone to adulteration by dubious street food vendors. In particular, food samples including fish stew, meat stew, fried eggs, salads, and unbottled drinking water were taken for microbial analysis from the study area. Standard microbiological methods were used for isolation, enumeration, and identification of bacteria. The SPSS software was used for the analyses and the significance level was set at p<0.05. Binary stepwise logistic regression analysis was used to investigate factors that may influence exposure of street-vended foods to pathogens. In the results, E. coli levels were found to be 100% and 60% in Nakawa and Naguru Parishes respectively. Microbial enumeration of Salmonella spp. was negative for all samples tested. Vendors who did not meet adequate personal hygiene standards, adjusted odds ratio, AdjOR: 0.96, CI: 0.85-0.99 and those who stored food at inappropriate temperatures, AdjOR: 0.88, CI: 0.47-0.97 were more likely to have their food exposed to pathogen spreading vectors. The presented results indicate that street foods vended in Nakawa and Naguru Parishes are a source of contamination as elucidated by presence of E. coli. Street food vending may be improved by supporting the identified at-risk groups

Occurrence Of Listeria Monocytogenes In Bulked Raw Milk And Traditionally Fermented Dairy Products In Uganda

Bulked raw milk, locally processed yoghurt (LPY) and Bongo, a traditionally fermented dairy product sold at most informal milk cooling points in Uganda, were assessed for occurrence of Listeria spp. and Listeria monocytogenes. Total plate counts (TPC), holding temperature, pH and titratable acidity were also determined in all the milk products at the point of collection using standard methods. A total of 40 samples of bulked raw milk and 30 for each of LPY and Bongo were examined. Listeria spp. was higher in bulked raw milk than in fermented milk. Listeria spp. were detected in 60% of bulked raw milk, 30% of LPY and 15% of Bongo samples. Bulked raw milk had significantly higher (p<0.05) mean Listeria counts (3.10±0.06 log10 cfu mL-1) than LPY and Bongo, 0.82±0.18 and 0.32±0.18 log10 cfu mL-1, respectively. L. monocytogenes was isolated from 13 % of bulked raw milk, 3.0% of LPY but was not detectable in Bongo. Total plate count was significantly different (p<0.05) among the different milk types studied. Bongo had higher TPC (9.00±0.13 log10 cfu mL-1) than bulked raw milk (8.40±0.11 log10 cfu mL-1) and LPY (7.40±0.13 log10 cfu mL-1). The mean total plate counts (4.90 to 9.00±0.13 log10 cfu mL-1) of the fermented dairy products were within the acceptable limits for human consumption. The TPC for bulked raw milk (8.40±0.11 log10 cfu mL-1) was higher than the recommended values of national and international standards. Temperature, pH and titratable acidity were significantly different (p<0.05) among the different milk types. Holding temperature ranged from 5.40 to 8.60oC, pH was 4.20±0.04 to 6.10±0.04 whereas titratable acidity ranged from 0.22±0.01 to 089±0.01%. Listeria counts were not statistically predictable (p>0.05) from variation in the combined effect of pH, percent titratable acidity and temperature. Results of this study demonstrate a high risk associated with consumption of bulked raw milk and fermented dairy products in due to occurrence of Listeria spp