Effect of disinfectants on adhered Aeromonas hydrophila to polyethylene immersed in water under static and dynamic conditions

Abstract

The growth of A. hydrophila in liquid medium was monitored a hyperbola of four stages of growth. The effect of Sodium hypochlorite (NaOCl) (0.5, 1 and 1.5 ‰) and Hydrogen Peroxide (H2O2) (5, 10 and 15 ‰) on the adherent cells under static and dynamic conditions on fragments of polyethylene immersed in water was assessed. Cells were harvested from different growth stages. With cells harvested from each growth stage, abundances of adhered A. hydrophila were generally lower in the presence of NaOCl and H2O2 than in their absence. With the 2 disinfectants, a significant difference amongst the average densities of adhered A. hydrophila at each growth phase was observed (P<0.05). The effectiveness of each disinfectant concentration on adhered A. hydrophila decreased as the duration of the adhesion increased. Although the adsorption coefficient obtained from Freundlich isotherms was relatively higher in the static than in the dynamic regime, no significant difference was observed between the mean abundances of A. hydrophila adhered under these two experimental conditions (P>0.05). NaOCl seems more effective on A. hydrophila adhered to polyethylene than H2O2. Adhered A. hydrophila to polyethylene under the dynamic condition was more sensitive to both disinfectants than that adhered under static condition. These results suggested that the incubation duration and the cell growth stage played an important role in the bacterial resistance mechanism towards disinfectants.