Abstract
In the past 15 years many divers strains have been assigned to the genus Brucella that differ from the homogenous classical core Brucella species. These novel, atypical Brucella spp. are gaining increasing interest in the scientific community while major information about their epidemiology, hosts, reservoirs, pathogenicity, and zoonotic potential are still missing, and more and more isolates are being reported. Inour case report, we describe brucellosis in a pair of White’s Tree frogs (Litoria caerulea) kept in a German zoo. Differential phenotyping of bacterial cultures was done with classical microbiological methods. Illumina sequencing reads were used for genomic characterization and phylogenetic positioning of the Brucella strain within the genus. The seriously ill White’sTree frogs were submitted for pathologic examination to the responsible chemical and veterinary investigation office. Both frogs were in a poor nutritional status and were presented with additional abnormalities, e.g. skin ulcerations and edema. Bacterial cultures from several organs of both frogs were positive for Brucella and were confirmed by polymerase chain reaction. A Brucella sp. isolate was forwarded to the German Federal Institute for Risk Assessment for in-depth analysis. This isolate displayed non-fastidious and rapid growth and predominantly showed microbiological characteristics similar to other novel, atypical Brucella strains, such as Brucella inopinata-like BO2 or Brucella sp. UK8/14, the latter also isolated from a White’sTree frog. Genomic and phylogenetic characterization placed the isolate apart from the core clade within the novel, non-core clade together with various amphibian and human isolates (inopinata- clade). In summary, we here report another case of amphibian brucellosis caused by anovel, atypical and non-core Brucella strain that clusters together with and is alike to previously reported isolates from amphibian hosts and human brucellosis patients underlining that exotic frogs are potential reservoirs for Brucella spp., posing an underestimated zoonotic hazard for exposed individuals (e.g. exoticanimal keepers, veterinarians).
