The present paper is a case-report of multiple udder infections in a dairy herd caused by Staphylococcus
microti. Over a 22-month period, eleven S. microti isolates from milk samples from 9 cows were collected.
The animals experienced subclinical (with one exception) intramammary infections with a high self-cure
rate. The identification of the microorganism was carried out by means of two independent approaches:
nucleotide sequence analysis of the 16S rRNA gene, as well as some housekeeping genes (sodA,rpoB, dnaJ),
and matrix-assisted laser desorption ionization—time of flight mass spectrometry. All S. microti isolates
belonged to an apparently single clone (as detected by the RAPD analysis), indicating that the
microorganism could adapt, to some degree, to the bovine mammary gland or even spread from cow to
cow in a contagious manner. This report is, to our knowledge, the first ever case of bovine mastitis caused
by S. microti and the first instance of isolation of this microorganism from domesticated animals.