A 19-year-old sexually active woman presents with acute dysuria and frequency. Urine culture grows catalase-positive, coagulase-negative Gram-positive cocci in clusters. The isolate is resistant to novobiocin. The most likely causative organism is:
- A Staphylococcus saprophyticus ✓
- B Staphylococcus epidermidis
- C Enterococcus faecalis
- D Staphylococcus lugdunensis
Correct answer: A. Staphylococcus saprophyticus
Explanation
Staphylococcus saprophyticus is a common cause of uncomplicated urinary tract infection in young sexually active women and is characteristically novobiocin resistant. Staphylococcus epidermidis, the most frequent distractor, is also coagulase negative but is novobiocin susceptible, which is the standard laboratory feature separating the two species.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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