Identification, differentiation and antibiotic susceptibility of Gallibacterium isolates from diseased poultry.

Background: Gallibacterium anatis is an opportunistic pathogen of intensively reared poultry causing oophoritis, salpingitis, peritonitis and enteritis. Gallibacterium anatis infection often remains undiagnosed. Recently multi-drug resistant isolates have been described.

Methods: A newly developed PCR restriction fragment length polymorphism assay targeting the 16S rRNA gene was used to identify and differentiate Gallibacterium isolates from chicken, turkey and partridge samples originating from 18 different geographical locations in Thuringia, Germany. Antimicrobial susceptibility to 19 compounds of different classes was assessed.

Results: Nineteen Gallibacterium isolates were investigated. In 9 birds (47.4%) Gallibacterium species were isolated exclusively while in 10 birds (52.6%) other bacterial or viral agents could be detected in addition. In one chicken a mixed infection of Gallibacterium anatis and Gallibacterium genomospecies was identified. All isolates were susceptible to apramycin, florfenicol and neomycin and resistant to clindamycin, sulfathiazole and penicillin. Resistance to sulfamethoxim, spectinomycin, tylosin and oxytetracycline was observed in 93.3%, 93.3%, 86.7% and 80.0% of the field strains, respectively.

Conclusions: The PCR-RFLP assay allows specific detection and differentiation of Gallibacterium spp. from poultry. Antimicrobial resistance of Gallibacterium spp. is highly significant in Thuringian field isolates.