Staphylococcus microti sp. nov., isolated from the common vole (Microtus arvalis)

Abstract

Two strains of Gram-positive cocci were isolated from viscera of common voles (Microtus arvalis Pallas) with generalized Brucella microti infection in the Czech Republic. Biochemical features and phylogenetic analysis based on 16S rRNA gene sequences showed that the strains are representatives of the genus Staphylococcus and assigned Staphylococcus muscae as the nearest relative. A detailed characterization done by ribotyping, rpoB and hsp60 gene sequencing, whole-cell protein analysis and rep-PCR using the (GTG) 5 primer differentiated the two strains from all described staphylococci. DNA-DNA hybridization with the type strain of S. muscae demonstrated that the two strains should be considered as members of a novel species (26.8 % reassociation). The two analysed strains were found to be coagulase-negative, novobiocin-susceptible, oxidase-negative cultures, phenotypically close to one another, but showing differences in ribotype profiles. The major fatty acids were iso-C 15 : 0 , iso-C 17 : 0 , anteiso-C 15 : 0 , C 18 : 2 v6,9c/anteiso-C 18 : 0 , C 18 : 0 and C 18 : 1 v9c. MK-7 was the predominant isoprenoid quinone, with minor amounts of MK-6 and MK-8. The polar lipid profile was composed of the major lipids diphosphatidylglycerol and phosphatidylglycerol and several unknown lipids. These results proved that the two isolates represent a novel staphylococcal species. The name proposed for this novel taxon is Staphylococcus microti sp. nov.; the type strain is 4005-LJ(m)At the time of writing, the genus Staphylococcus (family Staphylococcaceae) includes 50 species and subspecies that are common inhabitants of different mammals, humans, birds, cold-blooded animals and the environment.Staphylococci are isolated mainly from skin, glands, mucous membranes and, occasionally, from animal or human blood or viscera (Kloos et al., 1992). A study of staphylococcal distribution in different mammals (other than humans) and birds showed the predominant species to be the novobiocin-resistant, coagulase-negative species Staphylococcus xylosus and Staphylococcus sciuri (Nagase et al., 2002). These species were also predominant in tested laboratory mice. Staphylococcus intermedius is found frequently in a wide range of animal species, e.g. dogs, cats, mink and horses, and S. intermedius and Staphylococcus schleiferi subsp. coagulans are isolated as common pathogens in sick dogs. Natural populations of staphylococci in laboratory animals have been studied in Abbreviation: DDH, DNA-DNA hybridization.The GenBank/EMBL/DDBJ accession numbers for 16S rRNA gene, rpoB and hsp60 gene sequences of strain CCM 4903 T are EU888120-EU888122. The GenBank/EMBL/DDBJ accession numbers for other sequences determined in the study are EU888123-EU888134.Cluster analysis based on (GTG) 5 PCR and whole-cell protein SDS-PAGE profiles and results of 2D TLC of polar lipids of strain CCM 4904 are available as supplementary material with the online version of this paper.

Isolation of Staphylococcus microti from milk of dairy cows with mastitis

“…Interestingly, the identification kits used gave inconsistent results regarding the Voges-Proskauer test, with a positive reaction on API STAPH and negative one on ID 32 STAPH. To resolve this discrepancy and to address some differences between our results and those obtained by other investigators (Nováková et al, 2010;Riesen and Perreten, 2010), several phenotypic tests (for acetoin production, mannose fermentation and esculin hydrolysis) were also carried out using conventional methods. Our isolates tested negative in all these reactions.…”

“…Our isolates gave a positive reaction on the API STAPH strip and negative one on ID 32 STAPH and in the tube method. Given the reported weak reaction of S. microti for acetoin (Nováková et al, 2010), this phenomenon may have been associated with a different sensitivity of the identification systems used in the present study.…”

“…Only several isolates of this microorganism have been reported in the literature. For the first time, S. microti was recovered from internal organs of two common voles in South Moravia, Czech Republic (Nováková et al, 2010). Another isolate was found on the skin of a small mammal (belonging to rodents or insectivores) living in northeast Poland (Hauschild et al, 2010).…”

“…Both staphylococcal species were described for the first time in 2010 and recognized as distinct taxa based on DNA-DNA hybridization tests, analysis of the cell-wall structure and cellular fatty acids, as well as sequencing of the 16S rRNA and several housekeeping genes (Nováková et al, 2010;Riesen and Perreten, 2010).…”

“…Staphylococcus microti is a novel CNS species that was described on the basis of two isolates from internal organs of Brucellainfected common voles (Microtus arvalis) in the Czech Republic (Nováková et al, 2010). Phylogenetic studies based on the sequence analysis of the 16S rRNA gene and some housekeeping genes of S. microti have revealed that the microorganism is closely related to S. rostri and S. muscae (Riesen and Perreten, 2010).…”