How to Determine a Contaminant vs True Infection What is the organism? Most common contaminants: • Coagulase-negative Staph (82%) • Corynebacterium (not jeikieum) (>88%) • Bacillus spp. (not anthracis) (>92%) • Propionibacterium acnes (>94%) • Viridans group streptococci (50-55%) How many blood culture sets are positive? • More likely real if 2 out of 2 sets • Caveat: 2/2 is common for coag-neg Staph. Can check antibiograms (100% sensitive for same strain, 84% specific) or get species from the micro lab Original Slide by Dr. Jennifer Babik #BloodCultures #Contaminant #Contamination #Diagnosis #BCx #Laboratory #Interpretation
