Aim: The aim of this work was to isolate and molecularly identify enterohemorrhagic Escherichia coli (EHEC) O157 in milk and dairy products in Libya, in addition; to clear the accuracy of cultural and biochemical identification as compared with molecular identification by partial sequencing of 16S rDNA for the existing isolates. Materials and Methods: A total of 108 samples of raw milk (cow, she-camel, and goat) and locally made dairy products (fermented cow’s milk, Maasora, Ricotta and ice cream) were collected from some regions (Janzour, Tripoli, Kremiya, Tajoura and Tobruk) in Libya. Samples were subjected to microbiological analysis for isolation of E. coli that was detected by conventional cultural and molecular method using polymerase chain reaction and partial sequencing of 16S rDNA. Results: Out of 108 samples, only 27 isolates were found to be EHEC O157 based on their cultural characteristics (Tellurite- Cefixime-Sorbitol MacConkey) that include 3 isolates from cow’s milk (11%), 3 isolates from she-camel’s milk (11%), two isolates from goat’s milk (7.4%) and 7 isolates from fermented raw milk samples (26%), isolates from fresh locally made soft cheeses (Maasora and Ricotta) were 9 (33%) and 3 (11%), respectively, while none of the ice cream samples revealed any growth. However, out of these 27 isolates, only 11 were confirmed to be E. coli by partial sequencing of 16S rDNA and E. coli O157 Latex agglutination test. Phylogenetic analysis revealed that majority of local E. coli isolates were related to E. coli O157:H7 FRIK944 strain. Conclusion: These results can be used for further studies on EHEC O157 as an emerging foodborne pathogen and its role in human infection in Libya.
Hesham Taher Naas(11-2016)

Seventy five random samples were collected (25 raw milk, 50 local different made soft cheeses) from different supermarkets in Tripoli- Libya. The Objectives of this study were: (i)- to clear the incidence rate and count of coliforms as an indicator microorganisms for fecal contamination in raw milk and locally made soft cheese samples manufactured by traditional methods and (ii)- to make comparison between the most famous two conventional methods used for counting of such group of microorganisms. Coliforms were recovered from all the raw milk samples using the two methods (most probable number using liquid lauryl sulphate broth and sold plating method using violet red bile agar). The mean count for the former media was 28x106 while for the later one was 15x106 cfu/ml. For cheese samples (locally made Ricotta and Maasora), positive samples were 78% (39 samples) using MPN method, while 76% (38 samples) using sold plating media VRBA. The mean coliform count for positive samples using MPN was 18x107 cfu/g, while for VRBA plates the mean count for positive samples was 21x106 cfu/g. all counts were higher using MPN than VRBA for the same sample in both raw milk and cheese samples, although, clear difference in count between the two methods was recorded in cheese than that in raw milk, conditions that may affect the count in both raw milk and cheese were discussed. Factors that may limit
Hesham Taher Naas(1-2007)

This study determined the efficacy of actinidin and papain on reducing Listeria monocytogenes and three mixed strains of Escherichia coli O157:H7 populations on beef. The average reduction of E. coli O157:H7 was greater than that of L. monocytogenes and higher concentrations of either protease yielded greater reduction in bacterial populations. For instance, actinidin at 700 mg/ml significantly (p ≤ 0.05) reduced the population of L. monocytogenes by 1.49 log cfu/ml meat rinse after 3 h at 25 & 35 °C, and by 1.45 log cfu/ml rinse after 24 h at 5 °C, while the same actinidin concentration significantly reduced the populations of three mixed strains of E. coli O157:H7 by 1.81 log cfu/ml rinse after 3 h at 25 & 35 °C, and 1.94 log cfu/ml rinse after 24 h at 5 °C. These findings suggest that, in addition to improving the sensory attributes of beef, proteolytic enzymes can enhance meat safety when stored at suitable temperatures.
Hesham Taher Naas(12-2013)