Analysis of bacterial deversity found in dust filter of airconditioner in hospitals and residential buildings in Bangladesh

Abstract

Air conditioner (AC) is frequently used in hotter climates to stay cool indoors nowadays. However, Microbial contamination of air conditioners has emerged a public health concern owing to its increasing application in almost all building settings ranging from households, office to hospitals. Although the rising use of AC imposes risks, there is no comprehensive study conducted to evaluate bacterial profiles in these settings in Bangladesh. This research addressed the gap of limited data available on bacterial diversity of air conditioners and explored the prevalence of different microbial species present in the AC of hospitals and households adjacent to the respective hospitals in Bangladesh. The study was conducted by collecting swabs from the dust filter surface from hospitals and hospital adjacent households to compare the bacterial profiles between two different air conditioners of the same locality, observing higher bacterial levels in hospital, finding higher bacterial Colony Forming Unit (CFU) (approximately 105 in household and 109 in Hospital) and Extensive drug resistance in both hospital and household samples. Bacterial abundance was measured using CFU counts on Nutrient Agar followed by assessment on UTI selective Agar Bacterial identity was confirmed by MALDI-TOF, and evaluated risk through antimicrobial susceptibility testing (AST) revealed the antibiotic resistance profiles of respective bacterial species and potential risk associated with this. Among eight bacterial genera identified, Pseudomonas (50%), Acinetobacter (37.5%), Staphylococcus and Enterobacter (25%) were most. Moreover, in hospital AC, Pseudomonas, Acinetobacter, Enterococcus, Staphylococcus were predominant while in household AC Enterobacter, Acinetobacter, Pseudomonas genera are found to be significant. Bacteria identified from hospitals were found to differ significantly from households both in their abundance and diversity as well as Antibiotic Resistance Profiles. For instance, all bacteria isolated from household were Gram-negative, while those from hospitals were a mixed population of Gram-positive (42%) and Gram-negative (58%) bacteria. Moreover, 85% of bacteria in household are found to be extensively drug resistant and 100% of bacteria were extensively drug resistant in hospital AC. Among them, Enterobacter cloacae showed resistance to all antibiotics tested on AST panel. This study is expected to be the first of its kind in our country to annotate the microbial diversity in air conditioners, probable transmission and risk factors and finally help in policy making for increasing awareness and take necessary steps to prevent potential health hazards and suggest identification methods in future.