Enumeration of viable fungi in occupational environments: a comparison of samplers and media

Abstract

The performance of sampling for fungi using four widely used microbiological air sampling devices and three broad spectrum media was compared in seven occupational settings. Total colony forming units counts ranged from 10 to 3700 CFU/m3. The sampling efficiencies of the Andersen N-6 sampler, slit sampler, and Reuter centrifugal air sampler (RCS) were comparable, whereas the SAS sampler underestimated CFU counts by approximately 50%. The correlation between the RCS results and the other three samplers used was lower compared to their mutual correlations. There were no large differences in performance of the three media tested: malt extract agar, dichloran glycerol (18) agar, and dichloran rose bengal chloramphenicol agar. Coefficients of variation of duplicate samples were large compared to commonly used methods for sampling dust and chemicals. It is concluded that the N-6 and slit sampler perform best, although RCS is useful in probes because it is easy to handle. The three media tested yielded similar results. Further testing of DG-18 is recommended, as it inhibits fast growing genera and, thus, counting colonies is easier.