Pathogenic potential of Aeromonas hydrophila isolated from surface waters in Kolkata, India.
ABSTRACT Members of the genus Aeromonas (family Aeromonadaceae) are medically important, Gram-negative, rod-shaped micro-organisms and are ubiquitous in aquatic environments. Aeromonas species 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 of Aeromonas hydrophila isolates 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>or=100), damage to the gut and an inflammatory reaction in the mouse intestine; these effects were comparable to those of clinical strains of A. hydrophila and toxigenic Vibrio 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-resistant A. hydrophila in 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 genus Aeromonas.
- Indian pediatrics 10/2013; 50(10):969-70. · 1.04 Impact Factor
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ABSTRACT: The aim of this research is to study the adhesive properties of Aeromonas hydrophila to glass surfaces modified using four silanes with different reactive groups, namely (3-glycidoxypropyl) diethoxysilane, (3-N,N-dimethyl-3-N-n-hexadecylammoniopropyl)trimethoxysilane chloride, (3-N,N,N-triethanolammoniopropyl)trimethoxysilane chloride, and (3-N,N-dimethyl- 3-N-n-octylammoniopropyl)trimethoxysilane chloride. The strain used in the study was A. hydrophila LOCK0968, isolated from the unchlorinated communal water distribution system in Poland. The effect of glass modification after chemical treatment was analyzed using surface tension measurement. The adhesive properties of the bacteria were studied in a water environment with a low concentration of organic compounds, using luminometric and microscopic methods. Additionally, the viability of the adherent bacterial cells was evaluated by counting the colony-forming units. The presence of active compounds in the culture medium after incubation with a modified carrier was verified using the Kirby- -Bauer method. Half of the chemically modified glass surfaces exhibited better characteristics in comparison with native glass. Among the examined modifying agents, (3-N,N,N-triethanolammoniopropyl) trimethoxysilane chloride and (3-N,N-dimethyl-3-N-n-octylammoniopropyl) trimethoxysilane chloride showed the best antiadhesive and antibacterial properties. The most effective glass modification, with (3-N,N,N-triethanolammoniopropyl)trimethoxysilane chloride, was able to reduce the bacterial cell count by more than three orders of magnitude. The carriers had no significant effect on the viability of the free bacterial cells in the culture medium. Therefore, it can be said that the modified glass surface alone accounts for the antibacterial activity of the active organosilanes. Key words: Aeromonas hydrophila, antiadhesion, glass, silanes Introduction Aeromonas hydrophila are facultatively anaerobic, oxidase- positive, Gram-negative, non-sporulating rods with rounded endsFood Technology and Biotechnology 09/2013; 51(3):345. · 0.98 Impact Factor
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ABSTRACT: High incidence of mortality in carps was noticed in a polyculture fish farm situated in Orissa, India during March 2009 accounting for cumulative mortality of nearly 2% per day. The infected fish revealed gross ulcerative lesions on skin with erosion of scales and fin-and tail-rot. Acute tubular and diffused interstitial necrosis was observed in kidney tissue along with increased melanomacrophage reactions on histopathological examination. Hepatic and muscular necrosis was also noticed in most of the fish examined. The bacteria isolated from kidney, liver and blood samples were identified as Aeromonas hydrophila after biochemical characterization. This isolate was found to possess aerolysin, lipase, extracellular haemolysin and β-haemolysin genes contributing to its virulence. It was found sensitive to antibiotics amikacin, aztreonam, ceftazidime, ceftazidime, cefuroxime, cephotaxime, ciprofloxacin, co-trimoxazole, gentamicin, levofloxacin, nalidixic acid, netillin, nitrofurantoin, ofloxacin, streptomycin, tetracycline, tobramycin and trimethoprim. Experimental infection of Labeo rohita with this isolate resulted in similar clinical signs as those of collected from the farm. The LD50 dose was calculated to be 1.15 × 10 6 CFU/fish. This study suggests that A. hydrophila still remains an important bacterial pathogen from aquaculture point of view and regular examination of cultured fish is required to resist unexpected loss.Journal of Aquaculture. 07/2014; 16:27-37.