CLINICOPATHOLOGIC FEATURES OF INFECTION WITH NOVEL BRUCELLA ORGANISMS IN CAPTIVE WAXY TREE FROGS (PHYLLOMEDUSA SAUVAGII) AND COLORADO RIVER TOADS (INCILIUS ALVARIUS)

Authors

Kelly E. Helmick, American College of Zoological Medicine
Michael M. Garner, American College of Zoological Medicine
Jack Rhyan
Daniel Bradway

Document Type

Article

Date of this Version

2018

Citation

Journal of Zoo and Wildlife Medicine 49(1): 153–161

Comments

Copyright 2018 by American Association of Zoo Veterinarians

This document is a U.S. government work and is not subject to copyright in the united States.

Abstract

Two novel and distinct Brucella strains were recovered from 5 of 10 adult, sex undetermined, captive waxy tree frogs (Phyllomedusa sauvagii) and two of five adult, sex undetermined, captive Colorado river toads (Incilius alvarius) held in a zoologic collection with clinical and pathologic findings of bacterial disease. These amphibians originated from three separate private breeding facilities over several years and exhibited disease 9–49 mo following release from quarantine. Common presenting signs were vague but included focal abscessation, weight loss, change in coloration, anorexia, and decreased perching. Two waxy tree frogs and one Colorado river toad recovered with supportive care and antimicrobial treatment based on susceptibility testing. Microgranulomatosis, subcutaneous and renal abscessation, femoral osteomyelitis, and multicentric infection were the most common histologic findings. The organisms were identified antemortem in samples from subcutaneous abscesses, cloaca, and skin and from a variety of organ systems postmortem, and demonstrated a consistent susceptibility pattern. Initial isolates were misidentified as Ochrobactrum anthropi. Polymerase chain reaction and sequencing of the 16S rRNA gene identified the two organisms as novel Brucella strains similar to Brucella inopinata–like sp. and other novel organisms within the emerging ‘‘BO clade.’’ Brucella strain oaks (isolated from waxy tree frogs) and Brucella strain leathers (isolated from Colorado river toads) differed from each other by 16 of 571 base pairs in a region of chromosome 2, and did not closely match any previous GenBank entries. This report describes the clinicopathologic features of infection by these bacteria in two amphibian species and expands the range of novel Brucella organisms from amphibian reservoirs.