Isolation, characterization, and antibiotic sensitivity assessment of Gallibacterium anatis biovar haemolytica, from diseased Egyptian chicken flocks during the years 2013 and 2015

Gallibacterium anatis biovar haemolytica constitutes a part of the normal microflora in the upper respiratory and genital tracts of healthy chickens, but it is also associated with different pathological conditions. In the current study, 102 commercial chicken flocks suffering from respiratory disease and/or drop in egg production were investigated for the presence of G. anatis during 2013 and 2015. These flocks comprised 8 breeder, 32 layer, and 62 broiler flocks. By culture method, 20 flocks were found positive: one isolate derived from broiler breeders, 6 isolates from layers, and 13 isolates from broilers. G. anatis biovar haemolytica was identified by phenotyping and PCR. Additionally, partial genome sequencing of 11 isolates (5 layer isolates of 2013 and 6 broiler isolates of 2015) based on 16S rRNA and 23S rRNA gene sequences was performed and revealed 96.5% to 100% genetic relatedness. Antibiotic sensitivity of these isolates revealed that the 2013 isolates were highly susceptible to florfenicol while the isolates of 2015 were highly susceptible to cefotaxime. Gallibacterium anatis biovar haemolytica is a newly introduced bacteria in Egypt causing salpingitis, peritonitis, drop in egg production, and/or respiratory signs.