Enumeration of airborne bacteria and fungi using solid phase cytometry.

Conventional methods for the enumeration of airborne micro-organisms are inaccurate and time-consuming, hence the interest in novel approaches is increasing. In the present study, the use of solid phase cytometry (SPC) was evaluated for the enumeration of airborne micro-organisms. A 4 h SPC procedure based on viability staining was applied to samples from 50 locations and compared with an optimised culture-based method. Plate counts after air sampling were repeatable but strongly dependent on sampling volume. Samples with low or high microbial load were difficult to analyse using the culture-based method, unlike with SPC. Results show that SPC can be considered superior to the culture-based method because of its much higher dynamic range, its speed and its ability to enumerate not only culturable but all viable micro-organisms.