True statement regarding non-coagulase staphylococci is -
Staph epidermidis 

Most common coagulase negative staph. causing human infections.
It is present on the 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 poly­saccharide (slime) that facilitates the formation of a protective biofilm (slime layer) on the device surface. This biofilm acts as a barrier protecting bacteria from host defense 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.
They are non-pathogenic
They commonly infect indwelling prosthesis
They may cause scarlet fever
They are seperated by gram staining