A urine culture from a young female with catalase-positive gram-positive coccus (>100,000 CFU/mL) would most likely be which organism?

• A. Enterococcus faecalis
• B. Staphylococcus saprophyticus
• C. Streptococcus viridans
• D. Streptococcus bovis group

Answer: (B)

Think about uncomplicated UTIs in young, sexually active women. When the urine culture shows a large number of bacteria that are catalase-positive and gram-positive cocci, the culprits narrow to Staphylococcus species. Among them, Staphylococcus saprophyticus is the classic cause of UTIs in this group, so it best fits the scenario. Enterococcus faecalis is catalase-negative, and the Streptococcus species listed are also catalase-negative, making them less likely explanations for a catalase-positive, gram-positive coccus infection. The high colony count further supports a true infection rather than contamination, pointing to Staphylococcus saprophyticus as the most likely organism.