Tulathromycin treatment does not affect bacterial dissemination or clearance of Brucella melitensis 16M following experimental infection of goats

Authors: Boggiatto, Paola; Olsen, Steven

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2019
Publication Date: 12/10/2019
Citation: Boggiatto, P.M., Olsen, S.C. 2019. Tulathromycin treatment does not affect bacterial dissemination or clearance of Brucella melitensis 16M following experimental infection of goats. PLoS One. 14(12):e0226242. https://doi.org/10.1371/journal.pone.0226242.
DOI: https://doi.org/10.1371/journal.pone.0226242

Interpretive Summary: Brucella spp. are intracellular bacteria that cause persistent infections in the mammalian host. Brucellosis in sheep and goats is a significant source of economic loss and public health concern. In countries with a high prevalence of disease, test and removal programs are not economically feasible and may not be culturally or socially acceptable. Development of a cost-effective and efficacious antibiotic treatment against brucellosis would be beneficial for disease control, animal welfare, and human health. We evaluated whether a commercially-available antibiotic, tulathromycin (Draxxin), already approved for food animals, could be used to treat brucellosis in goats. This work will be of interest to scientists, regulatory personnel, and producers as a safe approach to the control of animal brucellosis.

Technical Abstract: Brucellosis in sheep and goats, a zoonotic disease primarily associated with Brucella melitensis infections, causes significant economic losses and public health concerns worldwide. Although control measures are effective, economic limitations and nomadic lifestyles may limit vaccination coverage, and test and removal policies may not be feasible. In this study, we evaluated the effects of therapy with a long acting antimicrobial tulathromycin on the pathogenesis of brucellosis. Thirty-five goats were randomly assigned for experimental infection with B. melitensis strain 16M while open or during mid-gestation. Approximately half of the animals in each group were then treated with tulathromycin and subsequently assessed for the development of humoral responses to infection, clinical presentation, and bacterial dissemination and colonization. All animals, regardless of treatment group were successfully challenged with B. melitensis 16M demonstrated by bacterial recovery from conjunctival swabs and development of positive antibody titers. In goats infected while open, no animals aborted and Brucella was recovered from only one animal in tulathromycin-treated and one animal from the untreated group. Tulathromycin treatment of pregnant goats did not prevent abortion nor did it reduce bacterial dissemination, colonization, or shedding. Our data suggests that treatment of goats in mid-gestation with tulathromycin at the labeled does not influence disease pathogenesis or tissue colonization after experimental B. melitensis challenge.