Prevalence of Listeria monocytogenes in ‘Khebab’, a Street-Vended Spicy Grilled Meat

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JUNE, 2018
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Meat and poultry products are reported to be the most frequently implicated vehicles of transmission of Listeria monocytogenes, a Gram-positive bacterium. Listeria monocytogenes is a foodborne pathogen causing diseases from severe blood and/or central nervous system infections to mild gastroenteritis. This study investigated the prevalence of Listeria monocytogenes in ‘Khebab’, a Street-Vended Spicy Grilled Meat in the Accra Metropolis. A survey was carried out using a structured questionnaire that had both observational and responsive questions for both the processor and the consumer. Microbiological laboratory analysis was employed using pour plate method, streak method and biochemical tests to isolate and identify contaminants in the ‘khebab’ samples. A total of 120 samples comprising of 60 skewed raw meats and 60 grilled skewed meats were analyzed. Results showed that, out of the 400 respondents who were Consumers, 196 (49%) were females while 204 (51%) were males. About half (49.75%) of the Respondents were in the age group ranging from 20-39 years. Those that were less than 20 years were 21.5% while only 12.5% were in the age range of fifty years and above ((≥50. About 361 (90.25%) of the respondents indicated that they consume ‘Khebabs” while only 39 (9.75%) indicated that they do not consume “khebabs”. A total of 20 processors who were all males and between the ages of 30-49 were recruited for this study. Out of the total number (20) 70% were in the age range of 30-39 while 30% were between 40 and 49 years. Six (6) had had Senior High School (SHS) education, seven (7) with Junior High School education (JSS), three (3) with primary school education while four (4) were illiterates. Majority (55%) of the processors bought their raw meat from the open market while 45% bought their raw meat from slaughter houses. The calculated Cohen’s Kappa co-efficient (k) was 0.02 implying a fair agreement in terms of Listeria monocytogenes contamination. Out of a total of 120 samples of meat consisting of 60 raw meats and 60 grilled meats (‘khebabs’) tested, 92 samples (76.67%) were positive for Listeria monocytogenes with 45 samples (48.91%) being raw meat and 47 samples (51.09%) being grilled meat. James Town vending area recorded the highest count of 5.046 ± 0.977 log10cfu/g whilst the least count of 2.239 ± 0.337log10 cfu/g was recorded in the Labone vending area for the raw meat. After the meat had been grilled, Banana Inn vending area recorded microbial count of 5.929 ± 1.064 log10cfu/g whilst the least count of 2.739 ± 0.370 log10cfu/g was recorded in the Tabora vending area. Madina had the highest load of TVC (7.267 log10 cfu/g) whilst Sowutuom vending area had the least TVC of 4.732 log10 cfu/g. Total coliform count (TCC) was the highest in the Banana Inn vending area (6.394 log10 cfu/g) whilst the lowest count of 0.00 log10 cfu/g was in the Dome, Legon, North Kaneshie, and Tabora vending areas. For the E. coli (EC) contamination, the highest level of 7.009 log10cfu/g was found in the Dansoman vending area whilst the lowest level of 0.00 log10 cfu/g was found in the Dome, Sowutuom, and Tabora vending areas. Thus, there should be education on food safety issues in order to protect the immuno-compromised individuals such as diabetics, AIDS patients, those with renal failure, organ transplant patients, cancer patients and pregnant women who are prone to Listeria monocytogenes and other pathogens. Listeria monocytogenes limit for all ready-to-eat food should be less than 100 colony-forming units per 25g or 25ml portion of the food according to WHO microbiological guidelines for ready-to-eat food. The microbial loads are therefore not below the WHO threshold value.  
A thesis submitted to the Department of Food Science and Technology, College of Science, in partial fulfilment of the requirements for the degree of Master of Science in Food Quality Management,