Isolation and characterization of Acinetobacter baumannii from environmental waters in Dhaka City, Bangladesh

Acinetobacter baumannii, a gram-negative bacterium commonly associated with nosocomial infections, has been relatively unexplored in the environmental context. The present study was conducted in Dhaka City, Bangladesh, with the primary objective of isolating and characterizing A. baumannii in environmental water sources. Surface water samples were collected from various water reservoirs to detect the presence of A. baumannii. Isolates were confirmed as A. baumannii using culture and PCR. Confirmed isolates were screened for antimicrobial susceptibility, antimicrobial resistance genes, and serum resistance. Results revealed that 32% of the water samples tested positive for A. baumannii. In total, 23 A. baumannii isolates were obtained. All isolates showed resistance to Cefepime. Varying degrees of resistance to other antibiotics were observed, and 56% showed resistance to the bactericidal effect of serum. This study underscored the remarkable adaptability of A. baumannii and its ability to flourish in diverse environmental conditions, highlighting public health concerns of increasing antibiotic resistant bacteria. The study concluded that, given the significance of effective infection control and sanitation and waste management measures, understanding the presence and behavior of A. baumannii in the environment is paramount. This study acts as the first report on environmental A. baumannii in Bangladesh and further research is warranted to elucidate the underlying mechanisms of antibiotic resistance and their implications for human health. • Molecular characterization confirmed 23 isolates as A. baumannii from 31 unique water sites in Dhaka City. • Resistance to cefepime was observed in all isolates (100%), with a significant proportion also displaying resistance to ceftazidime (65%) and imipenem (56%). • 30% of isolates were positive for NDM and OXA-48 genes, the latter being an atypical result. • A majority of the isolates (56.5%) were resistant to human serum.