Isolation of fungi in indoor air environment of selected air-conditioned and non-airconditioned wards in a public tertiary hospital in Metro Manila, Philippines

Abstract

Background and Objectives: The hospital as health care facility has also become a source of infection that provides a place for different microbiological agents such as fungi. Exposure to these organisms is specifically detrimental to highly immunocompromised in-house patients. This study aimed to 1) detect the presence of fungi in a public tertiary hospital in Metro Manila; 2) determine the dominating fungal organism; and 3) describe the environmental conditions and physical factors affecting the proliferation of fungal organisms.

Methodology: Eight sampling sites were selected for this study. The hospital main lobby was the comparison site for the three non-air-conditioned surgery wards (NACWs) while the fourth level nurse station is the comparison site for the air-conditioned wards (ACWs). Meteorologic conditions such as environmental temperature and relative humidity were also determined. Andersen air sampler was utilized to conduct the environmental indoor air sampling. A total of 98 malt extract agar supplemented with chloramphenicol (0.01%) plates were utilized for the duplicate sampling in eight sites. After three to five days of incubation at 37° C, the isolated fungal organisms were culturally and morphologically characterized.

Results: Seven fungal organisms were isolated from the indoor air sampling conducted namely: Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Curvularia sp., Penicillium sp., Alternaria sp. and Rhizopus sp.). The most dominant fungal species among the NACWs was A. niger. On the other hand, A. fumigatus was the most observed isolate among the ACWs. The air-conditioned wards showed a higher number of fungal isolates. In particular, A. fumigatus and A. flavus colonies in the ACWs were evidently higher than in the NACWs.

Conclusion: The ubiquitous nature of the Aspergillus species and slow settling rate due to small spore size make it the most dominant fungal organism retrieved in the air sampling conducted. No strict numerical guidelines were available for the spore counts of Aspergillus species to assess contamination rate. However, according to the Health Protection Surveillance Centre, 2018, the values of CFU/m³ of most of the isolates not only by Aspergillus species showed non-compliance with the threshold level documented.