Effect of improper use of some disinfectants used in the field on some selected E. coli Serovars

Abstract

The identified E. coli serovars Oll4:K-, 086, 086:K60 and 055:K39 used in this investigation were previously isolated from broiler chickens showing symptoms of chronic respiratory diseases. On post mortem examination they had typical lesions of chronic respiratory disease (perihepatitis, pericarditis and airsaculitis). Results could be summarized as follows:

1) Three disinfectants commonly used in poultry fanns: TH4+, VirkonS and Fonnalin were chosen for the present study. The effect of these disinfectant concentrations and exposure time on the survival of E .coli serovars were investigated. At 0.03%, 0.007% and 0.03% of formalin, TH4+ and Virkon S concentrations failed to kill the four E.coli ser"ovars within 360 mm, respectively.

2)The addition of the disinfectant together with the inoculum or at the beginning of the exponential phase was investigated. Formalin recorded the highest percentage of inhibition among the three disinfectants used in these experiments against the four tested serovars. The inhibition percentage for fonnalin added at zero time was quite similar to that added to log phase culture. On the other hand, both Virkon-S and TH4+ showed a better inhibitory effect when added with inocuhun at zero time. Serovars 055:K39 recorded the lowest inhibition percentage among the four E. coli serovars by using TH4+, Virkon-S and Fonnalin.