A 60-year-old woman with a urinary catheter develops a urinary tract infection. Culture grows novobiocin-resistant coagulase-negative Gram-positive cocci. Which organism is most likely?
- A Staphylococcus epidermidis
- B Staphylococcus aureus
- C Staphylococcus saprophyticus ✓
- D Staphylococcus lugdunensis
Correct answer: C. Staphylococcus saprophyticus
Explanation
Staphylococcus saprophyticus is novobiocin-resistant, distinguishing it from other coagulase-negative staphylococci (CoNS) like S. epidermidis which is novobiocin-sensitive. S. saprophyticus is a common cause of community-acquired UTIs in young sexually active women. S. aureus is coagulase-positive. S. lugdunensis is novobiocin-sensitive and can cause aggressive endocarditis.
Reference: Jawetz, Melnick, and Adelberg's Medical Microbiology, 28th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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