The determination of baseline fungal spore counts in air and water at Mater Dei hospital

Abstract

Fungal presence represents a constant threat in hospitals, especially for immunocompromised patients. Atmospheric fungi may cause several nosocomial infections, among which Aspergillus spp. is the most common etiological agent. Highly efficient air filters, restrictive access conditions and reverse osmosis systems do not completely eliminate atmospheric fungi; hence lays the importance to implement routine air and water sampling with respect to mycological investigations in hospital environments. This study was aimed to determine the baseline airborne and waterborne fungal counts at Mater Dei Hospital in a rapid, cost-effective manner, using the SAS Super 180 air sampler to extract air onto Sabouraud Dextrose Agar with Chloramphenicol (SDC) culture media. Water samples collected were filtered through nitrocellulose membrane filters which were then applied to SDC media. Colonies cultured were counted and identified, and the air and water fungal load was then calculated. As a result, the effectiveness of the preventive systems currently set in place was assessed. Areas equipped with different air filtration systems and varied restrictive conditions were tested during summer and winter seasons, on a period of 5 months. The outer hospital surroundings were used as a control for air sampling. High air filtration efficiency corresponded to a low air fungal load, while fungal presence in water was seen to drastically decrease with the installation of an additional water filter inside the water tap. The ultra clean operating theatres equipped with the most efficient air filters and highly restrictive access yielded a zero fungal spore count. Atmospheric fungi were seen to have a seasonal variation, with higher counts found during summer months. Results were consistent with those found in similar studies, where it was shown that the efficiency of air filtration systems and restrictive access conditions may prevent a high atmospheric fungal load. In future studies, fungal counts may be used as baseline values. Moreover, given that a zero presence of fungi is attainable at present; these findings may help in the design of the new Oncology centre in Malta.