Gallibacterium anatis was first reported as a cause of salpingitis and peritonitis in chickens in 1950. At that time it was tentatively named “cloacal bacteria”. Fifty-three years passed before this species was finally classified and named. G. anatis is a very common part of the upper respiratory tract and lower reproductive tract microflora in healthy chickens worldwide. In addition to this, G. anatis has been demonstrated as a cause of particularly salpingitis and/or peritonitis, either alone or in association with Escherichia coli, leading to lowered egg production. Accumulating evidence suggests that G. anatis has a predilection for ovarian and other reproductive tract tissues and that this may be an important part of its pathogenesis. Only recently, however, molecular biological tools specific to G. anatis have become available, why much is still to be learned about specific factors governing host-pathogens interactions. A 216 kDa RTX toxin, GtxA, have been demonstrated to assert a strong leukotoxic effect on chicken macrophages in vitro whereas a gtxA deletion mutant was strongly attenuated in an intraperitoneal challenge model in chickens. gtxA is widespread among G. anatis strains of global origin and appears to be a key determinant in the clash between G. anatis and the immunesystem. Another group of proteins, the F17-like fimbrial FlfA proteins seem to promote a tightly regulated interplay among G. anatis and host epithelial cells in different organ systems. A genome comparison including 24 Gallibacterium strains outlined three main flfA fimbrial operons, whereof flfA1 is the most common and may be implicated in the recently proposed ovarian tissue tropism in vivo.
As an exception within the Pasteurellaceae family, antimicrobial resistance is frequent entity challenging attempts to control infections with this organism. Preventive measures are mostly accounted for by farm-specific autogenous vaccines due to a very broad serological variation counting at least 27 serotypes described to date. Some success at identifying universal immunogens able of inducing protective immunity in a serotype-independent manner do however show promise for a more efficient and general method of prevention in the future.