Diagnostic value of DNA and (1-->3)- beta-D-glucan detection in serum and bronchoalveolar lavage of mice experimentally infected with Fusarium oxysporum.

A sensitive and highly specific nested PCR (nPCR) protocol was developed for the specific detection of Fusarium oxysporum DNA in clinical specimens. The diagnostic value of F. oxysporum-specific DNA and (1-->3)-beta-D-glucan (BDG) detection was subsequently evaluated in serum and bronchoalveolar lavage (BAL) specimens of mice infected intravenously with F. oxysporum conidia. Mice were sacrificed in groups of six daily up to day 8 and then on days 11 and 14. The F. oxysporum-specific DNA and BDG in serum and BAL specimens were detected using nPCR and a Fungitell kit, respectively. Cultures of lung homogenate of all of the infected animals yielded F. oxysporum and the fungus was also observed in KOH/Calcofluor mounts of 67 % of the tissues. The BDG (cut-off value 80 pg ml(-1)) and nPCR sensitivity in BAL and serum specimens was 15 and 98 %, and 92 and 75 %, respectively. Combined detection of F. oxysporum DNA and BDG in serum enhanced the sensitivity to 98 %. However, the kinetics of the two markers were slightly different. Whilst BDG positivity in serum remained high throughout the infection period, nPCR positivity declined slowly. The data obtained in this study suggest that combined detection of BDG and DNA in serum offers a sensitive and specific diagnostic approach for invasive Fusarium infection.