<prompt> Blood culture of a patient shows growth of gram positive cocci which are catalase positive and coagulase negative. The patient was on a CVP line last week. The most likely etiological agent is?Staphylococcus aureusStaphylococcus epidermidisStreptococcus pyogenesEnterococcus faecalis  <response>: Ans. b Staphylococcus epidermidisRef: Microbiology by Ananthanarayati and Paniker 8th ed. 655, 679STAPHYLOCOCCUS Gram positive cocci, coagulase and Catalase positive: Staphylococcus aureus Gram positive cocci, Coagulase negative: Staphylococcus epidermidis and saprophyticus. Staph. Epidermis infect most commonly through artificial device like: IV canula, Prosthetic device, shunts and implants. MCC of catheter associated blood stream infection: Staph. Epidermis MC organism causing prosthetic valve endocarditits: Staph. Epidermis. 