Staphylococcus epidermidis biofilm on a central venous catheter is being studied. Which component of the biofilm formation sequence does the ica operon (intercellular adhesin locus) encode for?
- A Primary attachment to the catheter surface via fibronectin-binding proteins
- B Production of polysaccharide intercellular adhesin (PIA) which mediates cell-to-cell aggregation in the accumulation phase ✓
- C Dispersal of biofilm by release of surfactant proteins
- D Resistance to vancomycin via altered penicillin-binding protein 2a
Correct answer: B. Production of polysaccharide intercellular adhesin (PIA) which mediates cell-to-cell aggregation in the accumulation phase
Explanation
Staphylococcal biofilm formation has two phases: (1) attachment — mediated by MSCRAMMs (microbial surface components recognising adhesive matrix molecules) such as AtlE, AAP and fibronectin-binding proteins; (2) accumulation — mediated by polysaccharide intercellular adhesin (PIA), a poly-N-acetyl glucosamine polymer encoded by the icaADBC operon. PIA cross-links cocci forming the multilayered biofilm matrix. Vancomycin resistance via PBP2a is a feature of MRSA (Staphylococcus aureus), not S. epidermidis.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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