The present project made an effort to study the efficacy of different drugs on various prevalent strains of Escherichia coil isolated from chickens that were submitted for postmortem at College Of Veterinary Sciences, Lahore and Veterinary Research Institute, Lahore and also by visiting various poultry farms in Lahore region. Six different antibacterial drugs which included Amoxycillin , Enorfioxacine, Neomycin Gentamycin, Furazolidone & Flumequne were used to observe the sensitivity of the isolates. In-vitro condition, Enrfloxacine. Gentamycin and Flumequne emerged as drugs of choice in order of their decreasing importance in the experiment.

The pathogenicity of the isolated strains was tested in Swiss white mice after viable cell count, 5 mice were injected interaperitoneally with the suspension of the isolated strain at the dose rate of 0.25 ml having 3x108 bacteria while 5 mice were kept as control.

The three best drugs were further tested for their efficacy in protecting the birds from Escherichia coil infection. A total of 225 birds, comprising of 75 broiler, 75 layer and 75 indigenous (Desi chicks), each type representing a group were reared upto 6 weeks of age. At 29th day of age, each of the three group was divided into 5 sub groups comprising 15 birds each. Four sub groups out of 5 of each type was injected with pathogenic isolates of E.coli, cultured already in fresh Nutrient broth and incubated at 37°C for 24 hours, having 3x108 bacteria per 0.25 ml interaperitoneally. One sub group of each type was kept as control (uninfected and untreated). One of the four infected sub groups in each type was not treated while the remaining three infected sub groups in each type were treated with Enrofloxacine, Gentamycin and Flumequene respectively. All the groups were kept under close observation and their mortality was recorded. Maximum mortality was recorded in sub group 1 of group A (i.e. 66.67%) while in the sub groups 2 of B & C, the mortality recorded was 60% and 66.66% respectively.

According to the trial Enrofloxacin afforded maximum protection against the infection and feed efficiency, Flumequen stood second and Gentamycin stood third in boilers.