Genotyping of Staphylococcus aureus isolated from bovine mastitis

The present study was designed to comparatively investigate 25 Staphylococc us aureus strains isolated from bovine subclinical mastitis. The S. aureus strains, obtained from six different farms at five locations in one region of Germany, were characterized by phenotypic and genotypic methods. The S. aureus could be identified and further characterized by their cultural, bio chemical and hemolytic properties. To analyze the epidemiological relations hip the isolates were subjected to DNA fingerprinting by macrorestriction a nalysis of their chromosomal DNA, by PCR amplification of the gene encoding the 16S-23S rRNA intergenic spacer, by PCR amplification of the gene encod ing the IgG binding region and the X region of protein A and by amplifying, and subsequent, digestion of the gene encoding staphylococcal coagulase. T he macrorestriction analysis revealed five DNA restriction patterns with DN A patterns I, III and IV occurring in three, four, and three different farm s, respectively. In addition, clones with different DNA patterns could be f ound within one herd. The PCR products for the spacer DNA, the spn gene enc oding the X region of protein A and the coa gene encoding coagulase corresp onded mostly to the pattern observed by DNA fingerprinting. Amplification o f the gene encoding the IgG binding region revealed sizes of 620 bp for 20 of the isolates and 280 bp for four isolates indicating, for the latter, a deletion of segments in this region. These findings show, that single, wide ly distributed clones seemed to be responsible for cases of bovine subclini cal mastitis found in one legion of Germany. (C) 1999 Elsevier Science B.V. All rights reserved.