Veterinary Microbiology 101 (2004) 101–107 Phenotypic and genotypic characteristics of Staphylococcus aureus isolates from raw bulk-tank milk samples of goats and sheep D. Scherrer, S. Corti, J.E. Muehlherr, C. Zweifel, R. Stephan ∗ Faculty of Veterinary Medicine, Institute for Food Safety and Hygiene, University of Zurich, Winterthurerstr. 272, CH-8057 Zurich, Switzerland Received 9 September 2003; received in revised form 18 February 2004; accepted 8 March 2004 Abstract Two hundred and ninety-three isolates of Staphylococcus aureus obtained from 127 bulk-tank milk samples of goats and sheep from Switzerland were characterised by pheno- and genotypic traits. Of the 293 S. aureus isolates, 193 (65.9%) were egg yolk-negative and 15 (5.1%) were negative for clumping factor and/or protein A determined by a latex agglutinating test system. For 285 isolates, PCR amplification of the 3 ′ end of the coagulase gene showed a single amplicon. Five differently sized PCR products of 500, 580, 660, 740 and 820 bp were distinguished. In 191 isolates (n = 293) staphylococcal enterotoxin (SE) genes were detected: 123 isolates tested positive for SEC gene, 31 for SEG gene, 28 for SEA gene, 26 for SEJ gene, 24 for SEI gene, 4 for SEB gene and 4 for SED gene. Furthermore, 126 isolates were positive for the gene encoding the toxic shock syndrome toxin 1. Coagulase gene restriction profile analysis of the 145 isolates harbouring SEA or SEC genes revealed six different patterns using AluI and five different patterns using HaeIII. In summary, within these two groups, high genotypic uniformity within the different sized coagulase gene amplicons was demonstrated. This is the first study providing comprehensive characterisation data of S. aureus strains originating from bulk-tank milk samples of goats and sheep. Remarkable differences in phenotypic traits between S. aureus originating from goats and sheep and bovine milk were found. Moreover, the high prevalence of toxin-producing S. aureus may be important as it is relevant to food hygiene. © 2004 Elsevier B.V. All rights reserved. Keywords: Staphylococcus aureus; Sheep; Goat; Bulk-tank milk; Phenotyping; Enterotoxin genes; Coa gene; CRP analysis 1. Introduction Staphylococcus (S.) aureus is worldwide the most important pathogen in food poisoning and causes gas- trointestinal symptoms like nausea, emesis, abdom- ∗ Corresponding author. Tel.: +41-1-6358651; fax: +41-1-6358908. E-mail address: stephanr@fsafety.unizh.ch (R. Stephan). inal cramps and diarrhea in humans. Five classical staphylococcal enterotoxins (SE) SEA–SEE have been recognised and sporadic cases as well as outbreaks due to these enterotoxins are described (Balaban and Rasooly, 2000; McLauchlin et al., 2000; Asao et al., 2003). Recently, new SE were identified: SEG, SEH, SEI, SEJ, SEK, SEL, SEM, SEN, SEO, SEP, SEQ and SEU (Zhang et al., 1998; Jarraud et al., 2001; Orwin et al., 2001; Letertre et al., 2003; Orwin et al., 2003). 0378-1135/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.vetmic.2004.03.016