Undoubtedly, necrotic enteritis is identified as one of the most threatening diseases which face poultry industry in Egypt and need radical solution to avoid huge economic losses. The present work was designed for typing Clostridium perfringens isolated from diseased chickens suspected to have necrotic enteritis from different outbreaks in six Governorates in Egypt (Gharbia, Dakhalia, Sharkia, Ismailia, North Sinai and Kafr El Sheikh) during the period from August to December 2018. Intestine and liver samples were obtained from eighty six diseased broiler chickens representing 60 flocks. C. perfringens was isolated and toxigenicity of the recovered isolates was determined by Nagler's and dermonecrotic reactions. Furthermore, multiplex polymerase chain reaction (PCR) targeting alpha, beta, epsilon and iota toxins' genes was performed for result confirmation and typing of the toxigenic isolates. Sixty-six C.perfringens isolates (38.37%) were recovered from 172 intestine and liver samples and twenty isolates (30.3%) were toxigenic and typed as C. perfringens type A producing alpha toxin only. These findings established the fact that alpha toxin is the only main toxin of C. perfringens type A which is basically responsible for its pathogenicity and virulence. In addition, most of the positively toxigenic isolates were isolated from hepatic lesions (15 isolates) rather than intestinal lesion (5 isolates). In conclusion, alpha toxin is a major toxin for NE development in chickens. Genotyping of Clostridium perfringens by multiplex PCR is a useful adjunct to diagnosis of necrotic enteritis in chickens.

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Necrotic enteritis (NE) caused by Clostridium perfringens type A and colibacillosis caused byAvian pathogenic E. coli (APEC), are two pathogenic diseases that threaten the poultry industry worldwide. A combined inactivated vaccine from Clostridium perfringens type A toxoid and serotypes O 1 and O 78 of E-coli adjvunated with montanide gel was prepared and evaluated in two weeks old SPF white Lohman layer chickens and its progeny. The prepared vaccine was found safe and produced antitoxic titre against NE of 10 IU after 22 week of vaccination as measured by serum neutralization test and 2692 ELISA titre. Also it produced a humeral antibody titre against E.coli serotypes used of 80 at the 22 th week post vaccination by microagglutination test (MAT) and an 80% protection in challenge against virulent E.coli serotypes used. Conclusion: vaccination of chicken with two doses, 3 weeks apart, of combined vaccine of Clostridium perfringens type A toxoid and serotypes O 1 and O 78 of E-coli adjvunated with montanide gel, could protect against necrotic enteritis and colibacillosis.