Emergence of virulent, multidrug-resistant, and genetically diverse Aeromonas hydrophila in foods of animal and aquatic origin from tribal regions of Northeastern India.

Abstract

Aeromonas hydrophila is an emerging zoonotic foodborne bacterial pathogen that causes gastro-intestinal and extra-intestinal infections in humans. A total of 361 samples including water (n = 195) and foods of animal and aquatic origin (n = 166) collected from tribal dwelling areas of Northeastern India were screened for the microbiological presence of A. hydrophila. Upon presumptive identification and molecular confirmation, the overall occurrence was 8.31% (30/361) with the highest rate observed in edible snails (13/38, 38.24%), followed by fish (4/14, 28.57%), pork (5/18, 27.78%), chicken (5/100, 20.0%) and domestic tap water (3/195, 1.54%). Multidrug resistance was observed in 13.33% (4/30) of the isolates, with the highest phenotypic resistance observed against amoxicillin-clavulanic acid (15/30, 50.00%). Phenotypic virulence, ascertained using adhesion forming ability, identified five isolates with strong ability out of 76.67% (23/30) isolates which harboured the ability to form adhesions on abiotic surfaces. Serine protease (ser) gene featured as the predominant virulence gene (23/30, 76.67%) among the isolates followed by act (16/30, 53.33%) which codes for cytotoxic toxin. Heatmap analysis with hierarchical clustering as well as Enterobacterial Repetitive Intergenic Consensus (ERIC) and Random Amplified Polymorphic DNA (RAPD)-based fingerprinting indicated wide genetic diversity among the isolates. Overall, the study highlights the emergence and circulation of adhesion-forming, multidrug-resistant A. hydrophila strains that carry clinically important virulence genes. These findings raise a potential public health concern for the tribal population of Northeastern India, known for their distinct culinary practices and food habits.