Bacterial Whack-a-Mole: Reconsidering the Public Health Relevance of Using Carbadox in Food Animals.

Lance B Price

doi:10.1128/mbio.01490-17

Abstract

ABSTRACTCarbadox is an antibiotic used to control dysentery and promote growth in swine in the United States; however, the drug also causes tumors and birth defects in laboratory animals. Despite this and because the drug has no analogs in human medicine, it is not considered “medically important” and can be used in livestock without veterinarian oversight. In their recent study, T. A. Johnson et al. (mBio 8:e00709-17, 2017, https://doi.org/10.1128/mBio.00709-17) demonstrated that carbadox has profound effects on the swine gut microbiome, including the induction of transducing phage carrying tetracycline, aminoglycoside, and beta-lactam resistance genes. In swine production, carbadox can be used in conjunction with other antibiotics (e.g., oxytetracycline) that could fuel the emergence of strains carrying phage-encoded resistance determinants. Johnson et al.’s findings underscore the potential unforeseen consequences of using antibiotics in livestock production and call into question our current methods for classifying whether or not a veterinary drug has relevance to human health.

Highlights

Antibiotic resistance has captured the attention of the public and policymakers around the world
While its potential carcinogenicity in humans has not been assessed by the U.S Environmental Protection Agency’s Integrated Risk Information System (IRIS) program or the International Agency for Research on Cancer, it has been banned from food animal production in the European Union and Australia based on its potential risk to people
By prospectively analyzing the gut microbiomes of swine fed standard doses of carbadox and swine given unmedicated feed, the authors showed an acute induction of prophage and transfer of phage-encoded antibiotic resistance genes

Summary

Introduction

Antibiotic resistance has captured the attention of the public and policymakers around the world. Large-scale, real-world studies have demonstrated that veterinary use of these antimicrobials can lead to resistant infections in people [9, 10]. There are those that belong to antibiotic classes that are used exclusively in food animals, including ionophores and the quinoxaline-di-N-oxide, carbadox.

Results

Conclusion