is coag neg staph in urine culture usually a contaminant
Skin Contamination and Blood Cultures. There are really only four bugs that are commonly contaminants when blood cultures are positive: 1  Coag negative staph (gram positive cocci). 2  Corynebacterium (gram positive rods).3  Propionibacterium acnes (anaerobic gram positive rods). 4  Bacillus species (anaerobic gram positive rods).kin Contamination and Blood Cultures. There are really only four bugs that are commonly contaminants when blood cultures are positive: 1  Coag negative staph (gram positive cocci). 2  Corynebacterium (gram positive rods).