A survey on the presence of listeria species in raw milk, ice cream and human stools with characterization of some isolates by SDS-page [electronic resource].

Includes references.

Listeric infections, caused by microorganisms of the genus Listeria, occur worldwide and in a variety of animals and man. Listeriosis was recognized as a food-borne human disease that prompted intense research activity. Thus, between April and September 2003, a total of 250 samples including raw marketable milk (50) and ice cream of both small and large scale producers (50 each) purchased from retail local markets, supermarkets and street vendors in Assiut City, as well as farm milk (50) and human stools of apparently healthy farm attendants (50) collected from dairy farms. These samples were examined to investigate the prevalence of Listeria species. Also, antibiotic sensitivity pattern as well as characterization of the isolated strains, by (SDS-P AGE), were performed to find out the degree of homogeneity between those isolates. Listeria spp could be detected in 3 (6%), 7 (14%),7 (14%) and 3 (6%) of examined raw marketable milk, small scale ice cream, farm milk and stools of attendants, respectively, while failed detection in large scale ice cream samples. L. grayi was identified in 2 (4%) in both raw marketable and farm milk and 5 (10%) in small scale ice cream, while L. murrayi was isolated in percentages of 2 , 4 , 6 and 2% from tested samples of marketable milk, small scale ice cream, farm milk and stools, respectively. Concerning L. monocytogenes, it has been recovered from only one (2%) sample of each of farm milk and attendant stool, which obtained from the same dairy farm. The serotyping of these pathogens revealed that isolates were of serotype OJ. Likewise, L . ivanovii was detected in one (2%) of each of farm milk and attendant stool samples. Furthermore, the antimicrobial susceptibility testing of the previous strains showed that they were susceptible to the used antibiotics in percentages ranged from 88.9-100%. Also, to study the degree of homogeneity between these strains, whole cell proteins of these strains were analysed by using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-P AGE). Key words: Listeria species, Raw milk, Ice cream, Human stool, Antimicrobial susceptibility, SDS-P AGE.

Summary in Arabic.