الفهرس 
.INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 118 |  |  |
| | | from | 118 | | |
Abstract
Kariesh Cheese, can be considered a good medium for bacterial growth due to their nutrient content and long storage duration. Several steps in their production can cause bacteriological hazards.Though pasteurization of milk can destroy most of the pathogens posing risk to public health, yet, the potential bacteriological hazards can still be found in the final products after pasteurization through the addition of contaminated ingredients or improper handling. The results indicate the unhygienic conditions prevailing during distribution or sale particularly where products are sold in open containers.
The main objective of the present study was to assess the quantitative risk of L. monocytogenes from consumption of farmer-made Kariesh cheese sold in Alexandria street markets.
To fulfill this objective a total of 113 kariesh cheese samples were taken during the study as follows:
• A total of 96 kariesh cheese samples were collected from 25 open street markets sold by female villagers in Alexandria.
• A total of 13 kariesh cheese samples were collected from grocery stores in the most popular markets in Alexandria.
• A total of 4 pasteurized kariesh cheese samples were collected from 3 main hypermarkets and 1 supermarket in Alexandria.
In the meantime, a total of 205 females were interviewed to assess the rate of consumptions of kariesh cheese.
The results of the present study revealed that:
• In center district, a totalof 23 out of 31 kariesh cheese samples representing 74.4% were positive for listeria spp. with counts ranging from 10 Cfu /g to 1.1×103 Cfu/g with a mean value of 2.03×102 Cfu/g, While,a total of 14 out of 31 samples representing 45.1% were positive for L.monocytogenes with counts ranging from 40 Cfu/g to 1.1×103 Cfu/g with a mean value of 2.7×102 Cfu /g., there were 8 samples out of 31 samples hadL.monocytogenes counts exceeding 100 Cfu /g representing 25.8%.
• In East district, a total of 24 out of 29 samples representing 82.7% were positive for listeria spp. with counts ranging from 20 CFU/g to 2.0×103Cfu/g with a mean value of 2.68×102 Cfu/g,while, a total of 13 out of 29 samples representing 44.8% were positive for L.monocytogenesis with counts ranging from 20 CFU/g to 1.1×103 Cfu/g. with a mean value of 1.96×102 CFU/g, there were 6 samples out of 13 samples had L.monocytogenes counts exceeding 100 CFU/g representing 20.6%
• In Montaza district, a total of 15 samples out of 18 samples representing 83.3% were positive for listeria spp. with counts ranging from 30 CFU/g to 4.7×104 Cfu /g with a mean value of 3.7×103 Cfu/g, while a total of 13 samples out of 18 samples representing 72.2% were positive for L.monocytogenes with counts ranging from of 30 CFU/g to 6×103Cfu/g. with a mean value of 6.3×102CFU/g, there were 6 samples out of 18 samples had L.monocytogenes counts exceeding 100 CFU/g representing 54.5%.
• In West district, a total of 17 samples out of 20 samples representing 85.0% were positive for listeria spp. with counts ranging from 20 CFU/g to 1.6×104 Cfu/g with a mean value of 1.25×103 CFU/g, while a total of 15 samples out of 20 samples representing 75.0% were positive for L.monocytogenes with counts ranging from 20 CFU/g to 1.6×103 Cfu/g with a mean value of 1.4×103 Cfu/g, there were 10 samples out of 20 samples had L.monocytogenes counts exceeding 100 CFU/g, representing 50.0%.
• In Gomrouk district, a total of 3 out of 5 samples representing 60.0% were positive for listeria spp. with counts ranging from 9.2×102 CFU/g to 1.2×103CFU/g with a mean value of 1.10×103 Cfu/g, while a total of 2 out of 5 samples representing 40.0% were positive for L.monocytogenes, with counts ranging from 1.2×103 CFU/g to 1.2×103Cfu/g with a mean value of 1.2×103 CFU/g, there were 2 out of 5 samples had L.monocytogenes counts exceeding 100 CFU/g representing 40.0%.
• In Amrya district, All samples collected from that market were positive for listeria spp. with counts ranging from 10 CFU/g to 2.0×102CFU/g with a mean value of 1.05×102 Cfu/g.while,a total of 4 samples out of 6 samples representing 66.6% were positive for L.monocytogenes with counts ranging from 50CFU/g to 2.0×102 Cfu/g with a mean value of 1.52×102 CFU/g.there were 3 samples out of 6 samples had L.monocytogenes counts exceeding 100 CFU/g representing 50.0%.
• As a total, 88 out of 109 raw kariesh cheese samples, representing 80.7%, were positive for Listeria spp with counts ranging from 10 Cfu/g to 4.7×104 Cfu/g with a mean value of 1.0×103 Cfu/g.
• A total of 61 raw kariesh cheese samples out of 109 samples, representing 55.9%, were positive for L.monocytogenes, with counts ranging from 20 Cfu/g to 1.6×104 Cfu/g, with a mean value of 6.4×102 Cfu/g. Also, 40 samples out of 109 had L.monocytogenes counts exceeding 100 CFU/g representing 36.6 %.Concerning pasteurized kariesh cheese samples, only one sample was positive forListeria spp out of four,and non waspositive for L.monocytogenes.
• L.monocytogenesis was isolated from 75.0% of raw kariesh cheesesamples sold from West district, 72.2% from Montaza district, 66.6% from Amrya district, 45.1% from Center district, 44.8% from East district and 40.0% from Gomrouk district, with no significant difference between them. In the meantime, a total of 50.0% of raw kariesh cheese samples sold fromWest district, 50.0% from Amrya district, 44.4% from Montaza district, 40.0% from Gomrouk district, 32.2% from Center district and 24.1% from Eastdistrict had L.monocytogenesiscounts exceeding 100 Cfu/g.
• During summer, 77.55% of raw kariesh cheesesamples were positive for Listeria spp. with mean count of 1.6×103 Cfu/g, compared to 83.33% during autumn with mean count of 5.7×102 Cfu/g, with no significant differences between them.
• A total of 95 raw kariesh cheese samples sold by street vendors were presented on floor, with prevalence of 80.0% of Listeria spp.The highest prevalence of Listeria spp was 90.0% in raw kariesh cheese sold beside eggs, and the lowest prevalence was 68.4% in raw kariesh cheese sold beside mesh cheese.. Also, the prevalence of Listeria spp in raw kariesh cheese sold in grocery store was 84.6%. Only one sample was presented on table with a count of 40 CFU/g. In the mean time, 80% of raw kariesh cheese samples sold by street vendors beside eggs were positive for L monocytogenesis, compared to 52.6% of raw kariesh cheese sold beside mesh cheese. Also, the prevalence of L monocytogenes in raw kariesh cheese sold in grocery store was 46.1%.
• 50.5% of raw kariesh cheese samples sold by street vendors beside eggs had L monocytogenesis counts exceeding 100 CFU/g, compared to 42.1% of raw kariesh cheese sold beside mesh cheese.
• A total of 162 females out of 205 representing 79.0% consumed kariesh cheese, and only 11 females consumed kariesh cheese daily. The majority of females (81) consumed 100gm to less than 200gm during a day, 49 females consumed less than 100g during a day and 32 females consumed more than 200gm during a day. In the mean time, 122 females (75.3%) out of 162 females consuming kariesh cheese, stored the cheese for days or more in the refrigerator and only 10 of them stored it in the freezer.
• The median dose of L. monocytogenesis consumed by sampled females, at a consumption of 100 gm kariesh cheese was 1.6×104 cfu and increased to 3.2×104 cfu at a consumption of 200 gm. The meancomsumed dose of L. monocytogenesiswas 6.4×104cfu at a consumption of 100 gm and increased to 12.8×104 cfu at a consumption of 200 gm.
• The probability of illness from Listeria monocytogenes from Kariesh cheese in Alexandria increased with the increase of the consumption of Kariesh cheese.For susceptible population( r values =1×10-5), at consumption of 100 gm of Kariesh cheese per day, the probability of illness or cases showed a median of 0.1 and at a consumption of 250 gm the probability of illness or cases showed a medianof 0.3, meaning very high risk.
• For non- susceptible population( r values =8×10-16), at consumption of 100 gm of Kariesh cheese per day, the probability of illness or cases showed a median of 1.3×10-11and at a consumption of 250 gm the probability of illness or cases showed a medianof 3.2×10-11, meaning low risk For all population( r values =5.3×10-11), at consumption of 100 gm of Kariesh cheese per day, the probability of illness or cases showed a median of 8.5×10-7and at a consumption of 250 gm the probability of illness or cases showed a medianof 2.1×10-6, meaning very high risk.
• In the light of the results, it is recommendedthe following:
• Implement immediate regulatory measures like good manufacturing practices (GMP) to increase food safety awareness among kariesh cheese producers, to educate them the safe food handling practices, improvement of sanitary condition during their production and apply pest control and rodent control measures to ensure microbiological safety of kariesh cheese.
• Supermarktes, hypermarkets and grossery stores are also recommended to maintain a suitable comditions during presentation of kariesh cheese to prevent cross contamination.