Urine culture from a 22-year-old woman with dysuria and frequency grows catalase-negative, Gram-positive cocci in chains that are non-haemolytic. The isolate is resistant to novobiocin. What is the most likely organism?

• A Staphylococcus saprophyticus ✓
• B Streptococcus agalactiae
• C Enterococcus faecalis
• D Staphylococcus epidermidis

Explanation

Novobiocin resistance is the classic identifying feature of Staphylococcus saprophyticus, which causes urinary tract infection in sexually active young women. S. epidermidis is novobiocin susceptible, which kills option D. Enterococci and Group B streptococci are not characterised by novobiocin resistance. Note that despite being called a saprophyte, this organism accounts for a significant proportion of community-acquired UTIs in this age group, second only to Escherichia coli.

Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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