This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Which 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: Staphylococcus saprophyticus is gram-positive and coagulase-negative staphylococci. Staphylococcus saprophyticus may be present on the normal human skin and the periurethral area and can cause urinary tract infection, paicularly in the sexually active women. The infecting strains are usually sensitive to most common antibiotics except nalidixic acid. Staphylococcus saprophyticus is novobiocin resistant. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 208