Aeromonas hydrophila and its relation with drinking water indicators of microbiological quality in Argentine

In Argentine, water municipal supplies disinfection is carried out by chlorine. We have isolated Aeromonas hydrophila from a chlorinated water supply in Buenos Aires that fulfilled Argentinean microbiological quality standards. It is an aquatic organism that could produce cytotoxins and enterotoxins associated with acute gastroenteritis and wound infections in human and hemorrhagic septicaemia of fish, reptiles and amphibians. The isolated strain produced protein bands at isoelectric point in the range of 4.6-5.3 lightly labile at 56 degreesC and heat labile at 100 degreesC non cholera antitoxin reactive in electrofocusing assay (IEF) and showed hemolytic activity thermolabile at 56 degreesC and 100 degreesC in 5% rabbit erythrocytes in phosphate buffered saline. A cytotoxic effect thermolabile at 56 degreesC and 100 degreesC and a cytotonic activity were demonstrated in Vero cell cultures. Survival assay of A. hydrophila and indicator organisms would show no correlation between their contamination sources. Biofilms production could explain the persistence of this gram negative pathogen organism in chlorinated tap water. A water system supply maintenance program and pasteurisation may be performed in spite of water chlorination.