You have isolated some bacteria from your skin. In a Gram stain, the cells appear as purple cocci, many in grape-like clusters. The organism is positive for the catalase test, but negative for the coagulase test. On a Mannitol Salt Agar plate, the organism grows poorly and fails to turn the plate yellow. Finally, a novobiocin sensitivity test on blood agar showed the organism to be sensitive. A likely suspect is .