A 25-year-old man with 3 weeks fever presented with tricuspid valve vegetation. The patient is an intravenous drug abuser. Most common cause of endocarditis in this patient is

Staphylococcus epidermidis is invariably present on the normal human skin. It is non-pathogenic ordinarily but can cause disease when the host defences are breached. It is a common cause of stitch abscess. It has a predilection for growth on implanted foreign bodies such as aificial hea valves, shunts, intravascular catheters and prosthetic appliances, leading to bacteremia. Hospital strains are multi-drug resistant. It can cause cystitis and central line-associated BSI. Endocarditis may be caused paicularly in drug addicts. Biofilm formation is an impoant factor in the pathogenesis. It is an extracellular polysaccharide matrix which protects bacteria from antibacterial agents and helping colonisation and resistance to infection. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 208