This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Which one of the following Gram positive organism is most common cause of UTI among sexually active women : 
Select and explain. 
A. Staphylococcus epidermidis, B. Staphylococcus aureus, C. Staphylococcus saprophyticus, D. Enterococcus
C: Staphylococcus saprophyticus
Answer: C: Staphylococcus saprophyticus 
Explanation: Remember:

MC cause of UTI - E. coli
MC cause of nosocomial UTI - E. coli
MC nosocomial infection - UTI
S. saprophyticus produce UTI characteristically in sexually active young woman
Enterococci and S.aureus cause infections in patients with renal stones or previous instrumentation or surgery.