Bacterial disease still has serious problem in the intensive poultry production. In the recent years, particular concern has been raised by high incidence of poultry infections by E. coli. Analyses of antibacterial properties of essential oils have been carried out by range of researches. This experiment aimed to study the effect of immunomodulators on the immunogenicity of vaccine E. coli O78. In this study 250 broiler chickens were used. They were divided into 5 separated groups all groups vaccinated with E. coli O78 cebel coarse spray vaccine, except control group, 2 groups treated with immunomodulators, 3 groups challenged with untyped E. coli strain, all chickens housed in separated anavar. First group was control, 2nd group was vaccinated only, 3rd group was vaccinated and challenged, 4th group was vaccinated and received immunomodulators and 5th group was vaccinated, received immunomodulators and challenged. All chickens were observed daily food consumption, weight gained mortality rate, lesion, bioavailability, and weekly collected blood samples from 2-5 birds. The results were summarized as follows; immunomodulators have positive effect on B.W.G, decreased mortality and morbidity rate. The challenge enhanced the effect of E. coli O78 vaccine and there was marked improvement in bioavailability, B.W.G and immune defense against bacterial and respiratory diseases. Also, immunomodulators increased immunogenicity against bacterial disease through enhancing immune response system, and had synergistic effect with vaccination against E. coli.

E. coli infections in avian species are an economic threat to the poultry industry worldwide. The spread of MDR bacteria has been recognized as an increasing problem in the veterinary and medical fields. The current study aimed to investigate the phenotypic and genotypic antimicrobial patterns of avian Pathogenic E. coli isolated from broiler chickens. Results of in-vitro antimicrobial susceptibility testing showed that E. coli isolates were more sensitive to imipenem only (72.4%). On the other hand, they were highly resistant to most of used antimicrobials including ciprofloxacin (95.9%), amikacin (94.9%), cefotaxime sodium (92.9%), gentamicin (89.9%), cefotriaxone (89.9%), topramycin (87.8%), sulphamethoxazole/trimethoprime (85.7%), ceftazidim (84.7%). Also, they were resistant to cefoprazone (79.9%), doxycycline (72.4%) and amoxycillin/clavulinic acid (69.4%). All the tested isolates of E. coli (100%) were multi drug resistant (MDR). PCR was applied on 15 MDR E. coli isolates to determine 4 genes responsible for antibiotic resistance included ampC, blaCTX, blaSHV and tetA (A). The results revealed that that ampC and blaCTX genes were the most prevalent found in all isolates (100%) while tetA (A) and blaSHV genes were harbored in 14 isolates (93.3%).