Microbiological assessment of air-conditioners used in Calabar, Nigeria

Abstract

Background: There is a rising heat level in Nigeria that has been associated with climate change which has a global reach, exposing millions of people to the risk of several health problems. Usually air conditioners are deployed in human dwellings to eradicate heat conditions but may serve as potential reservoirs of infection if not appropriately used and maintained.
Aim: This study was aimed to evaluate in-use air conditioners in Calabar, Nigeria for their role in the transmission of microbial infections between April and August, 2021.
Methodology: A cross sectional study was conducted to examine 100 air conditioners’ filters and 50 filtered air samples of the same air conditioners in use for potential bacterial and fungal pathogens. Each filter was wiped with sterile cotton wool swab moistened with sterile peptone water, while the filtered air samples were collected by placing the appropriate culture media plates against the air conditioner air stream in use. The culture plates were incubated at 37⁰C for 24-48hours and one Sabouraud Dextrose agar plate at room temperature for 2-7 days. Identification of the isolates was done using standard bacteriological and mycological methods.
Results: Comparatively, the filters were more significantly contaminated with bacteria 100 (100.0%) and fungi 73(73.0%), respectively (x2=62.567, P=0.00001) than the filtered air samples 24(48.0%) and 17(34.0%), respectively (x²=21.13, P=0.00001). All (100%) of the 100 air conditioner filter samples studied carried bacteria compared to 73(73.0%) which carried fungi (x²=31.12, P=0.0001). Also, air conditioner’s air stream samples carried insignificantly more bacteria 24 (48.0%) compared to fungi 17(34.0%) (x²=2.0258, P=0.1546). The most frequently encountered bacteria and fungi in the study were Bacillus species (50.8%) and Aspergillus niger (60.0%), respectively. Others were Aspergillus flavus (40.0%), Pseudomonas aeruginosa (20.2%), Staphylococcus aureus (13.7%), Klebsiella pneumoniae (9.7%), and Escherichia coli (5.6%).
Conclusion: This study concludes that air conditioners in-use in Calabar can play role in the transmission and spread of air borne infections. Measures should be taken to ensure implementation of the recommended healthy, periodic cleaning and maintenance as well as from microbiological screening of in-use air conditioners.