Staphylococci are widespread as commensals of humans and animals where they colonize the skin or mucous membranes. Staphylococcus saprophyticus is a coagulase-negative Staphylococcus, gram-positive uropathogen and frequently isolated from young female outpatients presenting with uncomplicated urinary tract infections. S. saprophyticus causes uncomplicated urinary tract infection (UTI) but no severe bacterial infectious disease as caused by S. aureus. The urease of S. saprophyticus is known to be a virulent factor for the persistent infection in the urinary tract. All of the virulence factors of S. aureus, such as coagulase, hemolysins, enterotoxins, extracellular matrixbinding proteins, and exoenzymes, are absent in the S. saprophyticus genome. Besides S. saprophyticus is a leading gram-positive uropathogen of uncomplicated UTI, a restricted group of gram-negative bacteria, including Escherichia coli, Proteus mirabilis, and Klebsiella spp. is often observed to cause uncomplicated UTI.
