A dedicated fungal culture medium is useful in the diagnosis of fungemia: a retrospective cross-sectional study

BACKGROUND Mortality for candidemia ranges from 15% to 35%. Current guidelines recommend inoculating blood into three aerobic and three anaerobic blood culture bottles when candidemia is suspected, without mention of a fungal blood culture bottle. OBJECTIVE To determine the value of the BACTEC Myco/F Lytic blood culture media in the diagnosis of fungemia. METHODS A two-year retrospective cross-sectional study was performed for patients who had fungemia with submitted BACTEC Plus Aerobic/F (Aer), BACTEC Plus Anaerobic/F (Anaer) or Myco/F Lytic (Myco) blood culture bottles. RESULTS The detection rate of fungemia was 77.4% in 93 patients with contemporaneously submitted blood culture bottles when limited to only Aer/Anaer culture results. The detection rate improved significantly with the addition of the Myco culture bottle results (p<0.0001). A logistic regression model showed that Myco culture bottle submissions were less useful for patients with appropriate anti-fungal therapy administered within 48 hours [OR = 0.18, 95% CI = (0.06, 0.49), p = 0.001] and those with fungal growth detected within 48 hours [OR = 0.33, 95% CI = (0.12, 0.89), p = 0.001]. Among a subset of patients with concordant blood culture results, those with Myco culture bottles submission allowed earlier fungal detection and speciation by at least one day in 27.5% and 25.0% of the cases respectively. CONCLUSION Our study highlights the importance of a dedicated fungal blood culture when fungemia is clinically suspected. Nearly a quarter of fungemias may be missed if a fungal blood culture is not performed.