
As an animal science Ph.D. student at Purdue University, Indiana, I’ve been studying the ecology of bacterial BRD pathogens, especially Histophillus somni, Pasteurella multocida, Mannheimia haemolytica and Mycoplasma bovis. These bacteria infect the lung usually after a stressful event for the animal, leading to BRD development. Interestingly, these pathogens can live in the nasal cavity of healthy animals also; thus, it is possible to quantify their abundance without sampling lung tissue post-mortem. I believe that determining the abundance of bacterial pathogens in the nasal cavity could lead to more accurate identification of BRD-affected animals. Additionally, by determining which pathogen is infecting the lung of an individual animal, farmers could give individualized treatment to each animal; thus, improving antibiotic stewardship. Given the expertise of our lab, led by Dr. Tim Johnson, we have been able to collect nasal swabs from healthy and BRD
cattle to quantify the abundance of BRD pathogens. For our preliminary study, we collected nasal swabs from a feedlot in Indiana. To our surprise, M. bovis and M. haemolytica had a higher abundance in the BRD animals than in healthy ones, suggesting the importance of these bacteria in detecting disease at that farm. Nonetheless, it is necessary to determine if the same results would be observed at different farms in the United States. As a result, I am currently quantifying the abundance of the BRD pathogens from samples collected from different beef and dairy farms across the country. I expect to be able to infer disease status from the abundance of bacterial pathogens from a nasal swab which will help farmers to better identify their sick cattle.