Organism which has specific affinity for growing around prosthesis -

Ans. is 'b' i.e., Staphylococcus epidermidis Staphylococcus epidermidis* Most common coagulase negative staph, causing human infections.* It is present on normal human skin (where it is the most abundant bacterial species) as well as in the oropharynx and vagina.* It is a common cause of stitch abscesses.* It has a predilection for growth on the implanted foreign bodies such as artificial heart valves, shunts, intravascular catheters and prosthetic appliances leading to bacteremia.* S. epidermidis is uniquely adopted to colonize these devices by its capacity to elaborate the extracellular poly- saccharide (slime) that facilitates formation of a protective biofilm (slime layer) on the device surface. This biofilm acts as a barrier protecting bacteria from host defence mechanisms as well as from antibiotics.* The surface - associated staphylococcal enzyme autolysin (Atle) may play a role in attachment to prosthetic surfaces, which are often coated with host serum or tissue constituents such as fibrinogen or fibronectin.* It can cause cystitis and endocarditis.* Staphylococcus epidermidis is the most common cause of prosthetic valve endocarditis (early onset, upto 12 months).