Assessment of airborne bacterial pathogens and antimicrobial resistance in selected urban areas of Dhaka city

Abstract

Airborne microorganisms in urban environments pose a substantial but often neglected public health risk, particularly in densely populated cities such as Dhaka, where intense human activity, traffic congestion, and inadequate environmental controls can facilitate the spread of pathogenic bacteria. This study investigated the presence, spatial distribution, and antimicrobial resistance patterns of selected airborne bacterial pathogens across ten locations in Dhaka city, including Badda, Khilgaon, Aftabnagar, Mohakhali, Mirpur-10, Mirpur-12, Hatirjheel, Farmgate, Panthapath, and TB Gate Quarter. Air samples were analyzed for Pseudomonas spp., Klebsiella spp., Staphylococcus aureus, Acinetobacter baumannii, and Escherichia coli using selective culture methods followed by molecular confirmation through DNA extraction, polymerase chain reaction (PCR), and gel electrophoresis, yielding characteristic amplicons of 618 bp, 130 bp, 279 bp, 353 bp, and 585 bp, respectively. The distribution of airborne bacteria varied notably among sites, with Khilgaon showing the highest diversity of detected pathogens, while Hatirjheel samples showed no detectable target organisms. Antibiotic susceptibility testing revealed an alarming prevalence of multidrug resistance among all isolates, as Staphylococcus aureus exhibited 100% resistance to all tested antibiotics, E. coli and Klebsiella pneumoniae showed complete resistance to most antibiotics with only partial sensitivity to nitrofurantoin and trimethoprim, and both Pseudomonas spp. and A. baumannii demonstrated extensive resistance, remaining mainly susceptible to last-resort antibiotics such as colistin and selected fluoroquinolones. Overall, the findings highlight the presence of multidrug-resistant airborne bacterial pathogens in Dhaka’s urban air and underscore the urgent need for routine air quality surveillance and strengthened public health and antimicrobial resistance control strategies.