Rapid quantification of viable fungi in hospital environments: analysis of air and surface samples using solid-phase cytometry

Abstract

Environmental surveillance is important in high-risk areas of hospitals to prevent fungal infections in immunosuppressed patients. Conventional culture methods for enumerating environmental fungi are time-consuming. In this field study, a solid-phase cytometry technique (SPC) and a more conventional culture-based method to quantify fungal contamination of hospital air and surface samples were compared. For the air sampling, a liquid cyclone air sampler was used with a flow rate of 300L/min for 10min in each of four hospital locations. Surface swabbing was done in two locations, with two different swab types. Samples from all areas were processed by SPC and by culture on malt extract agar. The mean airborne concentrations of viable fungi determined by SPC were about 1.5-fold higher than the mean concentrations obtained with the culture-based method. These differences for air samples were significant in three hospital environments. No significant difference was observed for surface samples between the two swab types and between the two analytical methods. One of the prominent advantages of SPC was its rapidity in comparison with the culture-based method (5h versus 5 days). In this study, we showed that SPC allows for rapid monitoring of viable fungi in hospital environments. SPC can thus be used to provide an early warning and a rapid implementation of corrective measures. Viable fungi detection may be an important tool to assess infectious risk in wards with immunosuppressed patients.