Microbiological Assessment of Indoor Air Quality in Selected Patient Wards at a Tertiary Hospital in Nigeria

Aims: Patients are at higher risk of nosocomial infections from pathogenic microbes contaminating the indoor air of hospitals. This study evaluated selected patient wards at University of Calabar Teaching Hospital (UCTH), for bacterial and fungal contaminants. The study also determined the microbial contamination level when compared to recommended sanitary standards.

Methodology: To determine microbial load, petri-plate gravitational settling method was used. The set-ups were exposed for one hour (at morning and noon) for passive sampling onto growth media plates, in accordance with the 1/1/1 scheme as stipulated by the index of microbial air contamination standard. Petri-plates were subsequently covered with lids and placed in a cold box. Samples were then transported to the laboratory for further evaluation. Sampling was performed in duplicates within three months, and further analysis were conducted based on standard protocols. Mean counts of bacteria and fungi was recorded and expressed as colony forming units (CFU/m3).

Results: Microbial counts in all wards surveyed ranged from ‘intermediate’ to ‘high’ when compared to the sanitary standards of the European Commission for non-industrial premises. However, the counts were within the WHO acceptable sanitary standard (<1000 CFU/m3). Eleven bacterial genera and seven fungal genera were identified. Isolated bacteria were Staphylococcus aureus (18.3%), CoNS (6.7%), Bacillus sp (13.3%), Streptococcus spp (6.7%), Corynebacterium sp (1.7%), and Micrococcus sp (1.7%), Pseudomonas aeruginosa (15%), Escherichia coli (10%), Klebsiella pneumoniae (10%), Acinetobacter baumannii (8.3%), Salmonella sp (5%) and Enterobacter sp (3.3%). Conversely, isolated fungal contaminants were A. niger (25.9%), A. flavus (20.4%), Penicillium sp (16.7%), Candida sp (9.3%), Rhizopus sp (3.7%), Mucor sp (7.4%), Cladosporium sp (14.8%), and Fusarium sp (1.9%).

Conclusion: Regular monitoring of indoor air quality in health-care settings is encouraged to effectively guide infection prevention and control strategies and to limit nosocomial infections occurrence.