Characterization of Staphylococcus xylosus strains isolated from humans clinical material.
|Year of publication||2004|
|MU Faculty or unit|
|Description||Objectives: Staphylococci are common inhabitants of skin, skin glands and mucous membranes of mammals and birds. Certain Staphylococcus species are found as aetiological agents of a variety of human and animal infections as well. S. xylosus and S. equorum represents two phylogenetically and biochemically close species. Although S. xylosus is usually only transient on humans and is primarily acquired from domestic animals and their products it has been isolated from clinical material, mainly from urinary-tract infections. It is difficult to distinguish S. xylosus and S. equorum on the base of the biotyping. S. equorum was isolated from animal sources, but it has not been isolated from human clinical specimens yet. Methods: A group of 18 presumptive S. xylosus strains isolated from human clinical specimens and reference strains (S. xylosus, S. equorum and S. gallinarum) were analysed by biochemical tests and ribotyping. Biochemical properties were tested by API Staph and ID 32 Staph kits and by conventional tests. Ribotyping was done with EcoRI and HindIII restriction enzymes and a probe complementary to 16S and 23S rRNA from E. coli. Results: Phenotypic data of key tests corresponded with species description of S. xylosus except for one intermediate strain S. xylosus/S. equorum. Some results obtained for acid production were different from S. xylosus description, but identification to the species level was acceptable. Ribotyping with EcoRI divided tested strains into two groups, the S. xylosus group and smaller group which, as we supposed, belongs to the S. equorum species. This group contained of two reference strains and four clinical isolates. Group S. equorum was clearly distinguished also with HindIII, but S. xylosus group was divided into three smaller groups by using HindIII. Results of ribotype profiles did not correspond with biochemical characterisation of the isolates. Conclusions: There were identified 17 S. xylosus strains and one intermediate strain S. xylosus/S. equorum by biochemical tests. Contrary to biotyping, the colony size on the P agar and the ribotyping with both used restriction enzymes, showed, that four strains from tested series represent S. equorum species. This is the first case of occurrence S. equorum in human clinical specimens. Ribotyping with EcoRI and with HindIII showed heterogeneous ribotype profiles. These results imply that this method could be suitable for intraspecies characterisation of S. xylosus and S. equorum.|