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Six isolates of an unknown Gram-positive, catalase-negative, chain-forming, coccus-shaped organism isolated from ovine and caprine mastitis were characterized by phenotypic and molecular taxonomic methods. On the basis of cellular morphology and the results of biochemical tests, the organism was tentatively identified as a streptococcal species. Comparative 16S rRNA gene sequencing studies confirmed that the organism is a member of the genus Streptococcus, with Streptococcus equi as its closest phylogenetic relative (98?8 % similarity). DNA-DNA pairing studies showed that the unidentified organism displayed more than 70 % relatedness to the type strains of S. equi subsp. equi and subsp. zooepidemicus. Despite the relatively high DNA-DNA reassociation values, biotyping and ribotyping allowed clear differentiation of the unknown bacterium from the two recognized subspecies of S. equi. On the basis of phenotypic and molecular genetic evidence, it is proposed that the unknown Streptococcus isolates from ovine and caprine mastitis be classified as a novel subspecies, Streptococcus equi subsp. ruminatorum subsp. nov. The type strain is CECT 5772 T (=CCUG 47520 T =Mt 167 T ).Mastitis is one of the most serious economic and health problems of small ruminant flocks worldwide (Las Heras et al., 1999). Streptococci, together with staphylococci, are the most prevalent micro-organisms responsible for mastitis in small ruminants (Menzies & Ramanoon, 2001). The main species of streptococci causing mastitis are Streptococcus agalactiae, Streptococcus dysgalactiae and Streptococcus uberis (Quinn et al., 1999), although unusual cases of mastitis caused by other species of streptococci such as Streptococcus equi subsp. zooepidemicus or Streptococcus parasanguinis have also been described (Fernández-Garayzábal et al., 1998a;Las Heras et al., 2002). The taxonomy of the genus Streptococcus has improved greatly in recent years as a result of the use of molecular chemical and genetic methods. In particular, the increased use of comparative 16S rRNA gene sequencing has clarified the identification of many taxonomically problematic or aberrant strains and has played a central role in the recognition of many novel streptococcal species, especially those from animals (Skaar et al., 1994;Devriese et al., 1997Devriese et al., , 1999Rurangirwa et al., 2000;Collins et al., 2002;Vela et al., 2002). During the course of a study of bacteria associated with mastitis in small ruminants, we have isolated, from different animals, six strains of Grampositive, catalase-negative, chain-forming cocci of uncertain taxonomic position. In this article, we report the results of phenotypic and molecular genetic studies of the taxonomy of these Streptococcus-like organisms. On the basis of the findings presented, we describe a novel subspecies of S. equi, Streptococcus equi subsp. ruminatorum subsp. nov.During a routine bacteriological survey to determine the aetiological agents of mastitis in small ruminants, six unidentified isolates were recovered from mas...

The anti-microbial susceptibility and genetic diversity of 65 strains of Streptococcus equi ssp. zooepidemicus (Sez) isolated from mares presenting clinical signs of endometritis was determined by disk agar diffusion and pulsed field gel electrophoresis (PFGE) methods, respectively. Overall, Sez isolates were susceptible to beta-lactams, enrofloxacin, trimethoprim-sulfamethoxazole and gentamicin. These anti-microbials could be recommended as empiric anti-microbial therapy in cases of endometritis caused by Sez. Pulsed field gel electrophoresis typing revealed a great genetic diversity (56 different PFGE macrorestriction profiles) and a low level of genetic relatedness amongst the isolates.