Posted Date
Effective Date
Update Type Miscellaneous




Blood Culture, Bacteria and Yeast

Order Code:                  BLD/BLDAE/BLDAN/BLDOT/BLDC

Fee Code:                     32206, 32207 (CPT 87040)


Positive blood cultures are tested using the BioFire® Blood Culture Identification 2 (BCID2) Panel. Recently, the MLabs Microbiology Laboratory has detected Candida tropicalis by the PCR based BCID2 assay in 5 unique patient blood cultures where yeast was not seen in the Gram stain, nor did C. tropicalis grow in culture. The potential for this type of false positivity for other organisms (Proteus, Pseudomonas, Enterococcus, etc.) has been described in the past and typically is attributed to “residual DNA” or nonviable organisms from the blood culture media manufacturing process.  Therefore, whenever we detect an organism by BCID2 that is not reflected in the Gram stain of the bottle, we include the following comment with the report:


BCID2 has detected an organism not seen in the Gram stain of the bottle. This may be due to detection of an organism below the limit of sensitivity of the Gram stain but may also be due to the presence of non-viable organisms and/or nucleic acids in blood culture media.”


And similarly on the culture side we have the following comment:


“BCID2 detected an organism that was not seen in the Gram stain and did not grow in culture. This is most likely due to the detection of non-viable organisms and/or nucleic acids in blood culture media.”


The Microbiology Laboratory has identified lot numbers 2347840 (exp 9/30/23) and 2326486 (exp 9/30/23) as having sporadic false positive results and is monitoring test results closely.  The referring client or clinician will be notified if any suspected false positive results are found.