BCI Research Update: Antimicrobial resistance

Antimicrobial resistance is a high profile and growing concern in veterinary medicine. Bovine respiratory disease (BRD) is one of the major health problems in the beef industry that is commonly addressed by treatment with antimicrobial agents. Researchers at the College of Veterinary Medicine at Kansas State University recently reviewed the current literature concerning antimicrobial resistance in bacteria associated with BRD (Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni). The scientific literature was searched using three different literature search engines and one hundred and five relevant articles were found. These articles were reviewed and included if they were in English and the research followed standards set forth by the Clinical and Laboratory Standards Institute. Only 16 articles met the inclusion criteria and were given thorough reviews. Because of the relatively small numbers of articles and the variability of the results reported in the articles, the ability to reach firm conclusions from the review were limited. However, looking only at the data from diagnostic laboratories, which probably represents the most severe cases of BRD, there appeared to be a decrease over time in the percentage of BRD bacterial isolates that were susceptible to commonly used antimicrobials for the three major BRD bacteria. Studies reporting levels of antimicrobial resistance of bacterial isolates associated with BRD found in healthy cattle showed much lower levels of resistance. The reason for the difference in resistance between pathogens from severe BRD cases and healthy cattle is not clear. It is possible that isolates from healthy cattle lack resistance mechanisms or these isolates may contain inactive resistance genes that are phenotypically expressed only following the administration of an antimicrobial for either treatment or control of BRD. Future research should address whether antimicrobial administration alters phenotypic expression of resistance genes.

Anim Health Res Rev December 2015

Vol. 16. No. 2 pp. 125-135

A Literature Review of Antimicrobial Resistance in Pathogens Associated with Bovine Respiratory Disease

K. DeDonder*, M. Apley