PURPOSE: Diseases related to fungal exposure are present in occupational and general environments. Methods to assess the exposure are important from diagnostic and preventive points of view. Traditional methods comprise counting of spores or viable organisms, PCA determinations and measurements of ergosterol. An alternative is to measure N-acetylhexosaminidase (NAHA) as a maker of fungal cell biomass.
METHODS: Air samples ca 2.5 m3 are taken with cellulose acetate filters 0.8µm pore size. One mL of a fluorogenic enzyme substrate is added to the filter followed by an alkaline buffer (the developer). The liquid in the filter holder is sucked out through the filter and collected in a cuvette and read in a fluorometer in units (U/ m3).
RESULTS: Sarcoidosis Measurements were made in homes of subjects with sarcoidosis (n=107) and controls (n=30) without respiratory disease. Subjects undergoing treatment of the disease (newly diagnosed or with recurrence) had significantly higher activities of NAHA in their homes than controls (33.6 and 39.9 vs. 10.0 U/m3). Among controls only 5 out of 30 subjects had levels of NAHA above the second quartile value (14 U/m3). Nocturnal asthma Measurements were made in the bedroom of subjects with nocturnal asthma (n= 36) and controls (n=25). Subjects with asthma had significantly higher activities of NAHA in their bedrooms as compared to controls (32.5 vs. 10.7 U/m3). If the material was divided according to the 2nd quartile of NAHA (14.0 U/m3) 27 out of 36 subjects with asthma had high values compared to 3 out of 22 of for the controls.
CONCLUSIONS: The results from the application examples show that measurements of NAHA are a useful tool to determine fungal exposure. The limited data that are available suggest a threshold exposure value of 30 NAHA.
CLINICAL IMPLICATIONS: Determination of fungal exposure is an important action for treatment and prevention in addition to clinical practice.
DISCLOSURE: The following authors have nothing to disclose: Ragnar Rylander, Barbara Salobir, Marjeta Tercelj
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