A 55-year-old man with prosthetic valve endocarditis grows coagulase-negative Staphylococcus (CoNS) from three separate blood culture sets. The most virulent species associated with prosthetic device infections and the one MOST likely to be β-lactam resistant is:
- A S. saprophyticus
- B S. epidermidis ✓
- C S. haemolyticus
- D S. lugdunensis
Explanation
S. epidermidis is the most common cause of prosthetic valve endocarditis among CoNS and is the paradigm of biofilm-producing device-related infection. It adheres to foreign surfaces via surface proteins (MSCRAMM family including AtlE, SdrF), forms biofilm via PIA (polysaccharide intercellular adhesin), and up to 80% of clinical isolates carry mecA, rendering them methicillin-resistant. S. saprophyticus causes UTI in young women. S. lugdunensis behaves like S. aureus in causing native valve endocarditis and carries its own virulence factors. S. haemolyticus has the highest level of glycopeptide tolerance among CoNS.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.