Are Blood Cultures Reported as Negative Truly Negative?

Diagnosis of bloodstream infections relies primarily on blood culture. Such cultures are usually incubated for 5 to 7 days in highly automated, standardized, continuously monitoring systems that report growth in the bottle when indication of a metabolic process (i.e., an increment in carbon dioxide concentration or a pressure change due to gas production or consumption) is detected. Slow-growing pathogens that produce insufficient carbon dioxide can be missed with such technology. But how frequent are such “false-negative” blood cultures?

Researchers in Israel investigated this issue using 13,252 blood cultures submitted to their institution's microbiology laboratory between June 2013 and May 2014 and processed with the Bactec FX System. Aer…