A case of Staphylococcus saprophyticus bacteremia caused by obstructive pyelonephritis.

Herein, we present the case of a 64-year-old woman diagnosed with left calculous pyelonephritis. Gram-positive cocci in clusters were isolated from two sets of her blood culture. These cocci were later identified as Staphylococcus saprophyticus. Although S. saprophyticus is a common causative pathogen of urinary tract infection (UTI) among young women, coagulase-negative staphylococci including S. saprophyticus isolated from UTI patients' blood samples were often considered a result of contamination because of their rareness. Considering the high percentage of methicillin-resistant strains of S. saprophyticus, accurate strain identification and antimicrobial susceptibility testing are necessary to detect true bacteremia and its appropriate treatment.