High incidence of positive fungal DNA in the blood of critically ill patients

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Introduction

Systemic fungal infection is not uncommon in critically ill patients. Because of difficulty in the diagnosis, early antifungal therapy is not always possible. Although positive blood culture for fungus is well recognized as a hallmark of systemic therapy, sensitivity of blood culture is low. Detection of fungal DNA in the blood is expected to serve as a new clue to initiate antifungal therapy.

Purpose

To assess the incidence of positive fungal DNA in the blood of critically ill patients.

Methods

34 blood samples were obtained from 24 patients. Blood samples were processed for polymerase chain reaction (PCR) to detect fungal DNA. DNA extraction was performed with the modified methods of Buchman. PCR primers to amplify conserved DNA sequences of 18S rRNA genes shared by most clinically important fungi were used. The amplification was performed in a thermal cycler through the cycles as follows.

Results

Fungal DNA was detected from the 16 samples taken from 22 patients with SIRS and from seven samples taken from 12 patients without SIRS. When patients developed SIRS after seventh hospital day, fungal DNA was detected in 80% of samples taken from these patients.

Conclusions

Incidence of positive fungal DNA was more than 50% and the incidence reached 80% when patients developed SIRS after seventh hospital day. High incidence of positive fungal DNA suggests that there are more candidates for systemic antifungal therapy than expected.