Pathogenic potential of Aeromonas hydrophila isolated from surface waters in Kolkata, India

Abstract

Members of the genusAeromonas(familyAeromonadaceae) are medically important, Gram-negative, rod-shaped micro-organisms and are ubiquitous in aquatic environments.Aeromonasspecies are increasingly recognized as enteric pathogens; they possess several virulence factors associated with human disease, and represent a serious public health concern. In the present study, putative virulence traits ofAeromonas hydrophilaisolates collected from different natural surface waters of Kolkata, India, were compared with a group of clinical isolates from the same geographical area using tissue culture and PCR assays. Enteropathogenic potential was investigated in the mouse model. Of the 21 environmental isolates tested, the majority showed cytotoxicity to HeLa cells (81 %), haemolysin production (71 %) and serum resistance properties (90 %), and they all exhibited multi-drug resistance. Some of the isolates induced fluid accumulation (FA ratio≥100), damage to the gut and an inflammatory reaction in the mouse intestine; these effects were comparable to those of clinical strains ofA. hydrophilaand toxigenicVibrio cholerae. Interestingly, two of the isolates evoked a cell vacuolation effect in HeLa cells, and were also able to induce FA. These findings demonstrate the presence of potentially pathogenic and multi-drug-resistantA. hydrophilain the surface waters, thereby indicating a significant risk to public health. Continuous monitoring of surface waters is important to identify potential water-borne pathogens and to reduce the health risk caused by the genusAeromonas.