Time to blood culture positivity as a marker for catheter-related candidemia

The Infectious Diseases Unit, and Microbiology Laboratory, Tel Aviv Sourasky Medical Center, The Infectious Diseases Unit, and Microbiology Laboratory, Assaf Harofeh Medical Center, Zerifin; and The Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel

^* To whom correspondence should be addressed. Email: rbenami{at}mdanderson.org.

	Abstract

Candida spp are important causes of nosocomial bloodstream infection. Around 80% of patients with candidemia have an indwelling central venous catheter (CVC). Determining whether the CVC is the source of candidemia has important implications for patient management. We assessed whether the time to detection of Candida spp in peripheral blood (time to positivity, TTP) can serve as a marker for catheter related candidemia. Prospective surveillance of Candida bloodstream infection was conducted in two medical centers. TTP was recorded by the BacT/Alert automated system. Sixty-four candidemia episodes were included. Fifty patients (78%) had an indwelling CVC. Thirteen patients (20.3%) had definite catheter related candidemia. TTP was shorter in definite catheter related candidemia (17.3 ± 2 hours) compared with candidemia from other sources (38.2 ± 3 hours, P<0.001). A TTP cutoff of 30 hours was 100% sensitive and 51.4% specific for catheter related candidemia (area under the receiver operator characteristics curve 0.76). We conclude that TTP in peripheral blood is a sensitive but nonspecific marker for catheter related candidemia, and that a TTP of more than 30 hours can help exclude an intravascular catheter as the possible source of candidemia.