The aim of the present study was to investigate the incidence of G. anatis infection in commercial broiler and layer chickens in El-behira and Alexandria governorates, Egypt. A total of 64 chicken flocks (53 broiler, 6 layer and 5 breeder flocks) suffering from rales, sneezing and decreased egg production (in layer and breeder flocks) were examined by collecting swabs from trachea, oviduct and ovarian tissues. The molecular identification for the suspected samples, using PCR primers targeted the 16S rRNA (1133fgal) and 23S rRNA (114r) genes revealed 23.43% (15/64) positive isolates of G. anatis. The in-vitro antibiotic sensitivity testing was done and revealed that almost all isolates were sensitive to cefotaxime, norfloxacin, doxycycline and florfenicol. According to the clinical signs, PM lesions and histopathological lesions in commercial broiler chickens infected experimentally there was a significant differences in the pathogenicity in commercial broiler chickens among the 10 isolates used.
Key words: Gallibacterium anatis, antibiotic, chickens, pathogenicity, PCR.