ABSTRACTStaphylococcus saprophyticusis the only species ofStaphylococcusthat is typically uropathogenic and possesses a gene coding for ad-serine-deaminase (DsdA). Asd-serine is prevalent in urine and toxic or bacteriostatic to many bacteria, it is not surprising that thed-serine-deaminase gene is found in the genome of uropathogens. It has been suggested thatd-serine-deaminase or the ability to respond to or to metabolized-serine is important for virulence. For uropathogenicEscherichia coli(UPEC), a high intracellulard-serine concentration affects expression of virulence factors.S. saprophyticusis able to grow in the presence of highd-serine concentrations; however, itsd-serine metabolism has not been described. The activity of thed-serine-deaminase was verified by analyzing the formation of pyruvate fromd-serine in different strains with and withoutd-serine-deaminase. Cocultivation experiments were performed to show thatd-serine-deaminase confers a growth advantage toS. saprophyticusin the presence ofd-serine. Furthermore,in vivocoinfection experiments showed a disadvantage for the ΔdsdAmutant during urinary tract infection. Expression analysis of known virulence factors by reverse transcription-quantitative PCR (RT-qPCR) showed that the surface-associated lipase Ssp is upregulated in the presence ofd-serine. In addition, we show thatS. saprophyticusis able to used-serine as the sole carbon source, but interestingly,d-serine had a negative effect on growth when glucose was also present. Taken together,d-serine metabolism is associated with virulence inS. saprophyticus, as at least one known virulence factor is upregulated in the presence ofd-serine and a ΔdsdAmutant was attenuated in virulence murine model of urinary tract infection.
Molecular Epidemiology of Staphylococcus saprophyticus Isolated from Women with Uncomplicated Community-Acquired Urinary Tract Infection
