title: Enterotoxin Gene Profile and Molecular Characterization of Staphylococcus aureus Isolates from Bovine Bulk Milk and Milk Products of Tigray Region, Northern Ethiopia.
abstract: Staphylococcal food poisoning (SFP) is an important foodborne disease worldwide, and milk and milk products are commonly associated with SFP outbreaks. The objectives of this study were to investigate the distribution of staphylococcal enterotoxin (se) genes in Staphylococcus aureus from raw cow's milk and milk products and to assess their genetic background with the spa typing method. Of the 549 samples (297 bulk milk and 162 milk product samples) collected from Tigray region, Northern Ethiopia, 160 (29.1%) were positive for S. aureus, of which 82 (51%) were found to harbor se genes by a modified multiplex PCR. Nine se genes were identified: sea (n = 12), seb (n = 3), sec (n = 3), sed(n = 4), seg (n = 49), seh (n = 2), sei (n = 40), sej (n = 1), and tsst-1 (n = 24). The classical type of genes accounted for 27%. Of the 82 enterotoxigenic isolates, 41.5 and 12.4% harbored two or more se genes, respectively. The highest gene association was observed between sei and seg, whereas sea and seb were always found together with the new types of se genes. Altogether, 18 genotypes of toxin genes were identified, and 33% of the samples contained > 5 log CFU ml(-1) S. aureus. spa typing identified 22 spa types and three novel spa sequences, which showed the high genetic diversity of the isolates. No apparent relationship was observed between spa type and se genes. Of the 25 spa types, 13 (52%) were from raw milk, 3 (12%) from milk products, and 9 (36%) from both types of sample. Types t314 (20.7%,n = 17), t458 (18.3%, n = 15), and t6218 (9.8%, n= 8) were the most common spa types identified and were widely distributed in three of the eight studied localities. This is the first study from the Tigray region to report the high distribution of enterotoxigenic S. aureus with a diversified genetic background from dairy food. The study may provide valuable data for microbial food safety risk assessment, molecular epidemiology, and phylogenetic studies of S. aureus in Ethiopia.
authors: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, N-1432 Ås, Norway; College of Veterinary Medicine, P.O. Box 1118, Mekelle University, Mekelle, Tigray, Ethiopia. tenquebaher@yahoo.no enquebaher@yahoo.com.
authors: Enquebaher K
authors: EK
authors: Tarekgne
authors: Norwegian Veterinary Institute (NVI), Ullevålsveien, 68, Pb 750 Sentrum, N-0106 Oslo, Norway.
authors: Taran
authors: T
authors: Skjerdal
authors: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, N-1432 Ås, Norway.
authors: Siv
authors: S
authors: Skeie
authors: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, N-1432 Ås, Norway.
authors: Knut
authors: K
authors: Rudi
authors: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, N-1432 Ås, Norway.
authors: Davide
authors: D
authors: Porcellato
authors: French Agency for Food, Environmental and Occupational Health and Safety, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort, Paris, France.
authors: Benjamin
authors: B
authors: Félix
authors: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, N-1432 Ås, Norway.
authors: Judith A
authors: JA
authors: Narvhus
mesh_terms: D000818:Animals; D002417:Cattle; D004269:DNA, Bacterial; D004768:Enterotoxins / Q000235:genetics; D005002:Ethiopia; D005260:Female; D005506:Food Contamination; D005516:Food Microbiology; D008892:Milk / Q000737:chemistry / Q000382:microbiology*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D013211:Staphylococcus aureus / Q000302:isolation & purification*
chemical_list: D004269:DNA, Bacterial; D004768:Enterotoxins