Genotypic and phenotypic variation among Staphylococcus saprophyticus from human and animal isolates

BACKGROUND: The main aim of this study was to examine the genotypic and phenotypic diversity of Staphylococcus saprophyticus isolates from human and animal origin. FINDINGS: In total, 236 clinical isolates and 15 animal isolates of S. saprophyticus were characterized in respect of the occurrence of 9 potential virulence genes and four surface properties. All strains were PCR positive for the regulatory genes agr, sar >it>A and rot as well as for the surface proteins UafA and Aas. Nearly 90% of the clinical isolates were found to possess the gene for the surface-associated lipase Ssp and 10% for the collagen binding MSCRAMM SdrI. All animal isolates were negative forsdrI. Lipolytic activity could be detected in 66% of the clinical and 46% of the animal isolates. Adherence to collagen type I was shown of 20% of the clinical strains and 6% of the strains of animal origin. Most S. saprophyticus strains showed hydrophobic properties and only few could agglutinate sheep erythrocytes. CONCLUSIONS: We described a broad analysis of animal and human S. saprophyticus isolates regarding virulence genes and phenotypic properties such as lipase activity, hydrophobicity, and adherence. While S. saprophyticus strains from animal sources have prerequisites for colonization of the urinary tract like the D-serine-deaminase, out findings suggested that they need to acquire new genes e.g. MSCRAMMS for adherence like sdrI and to modulate their existing properties e.g. increasing the lipase activity or reducing hydrophobicity. These apparently important new genes or properties for virulence have to be further analyzed.