Kansas State Veterinary Diagnostic Laboratory research this summer revealed that drug resistance in one of the primary pathogens that causes BRD, Mannheimia haemolytica, has increased over a three-year period.
"We have been seeing an increase in the number of antibiotic resistant bacteria that cause pneumonia (also called BRD) in cattle," said Brian Lubbers, assistant professor in the diagnostic lab, based at Kansas State University. "Many of these bacteria are resistant to, not one, but almost all of the antibiotics that we use to treat pneumonia in cattle."
The economic toll from BRD has been estimated to approach $1 billion annually in the United States alone, if drug and labor costs, decreased production, and animal death losses are taken into account.
What hasn't been examined in depth is the cost of antimicrobial resistance in BRD cases, Lubbers said. Together he and Gregg Hanzlicek, also an assistant professor in the diagnostic lab, examined records of cases in which specimens of bovine lung tissue were submitted to the diagnostic lab from 2009 to 2011.
Most of the samples – 55 in 2009, 155 in 2010 and 180 in 2011, were from cattle in Kansas and Nebraska.
They found that over that period, a high percentage of M. haemolytica bacteria recovered from cattle lungs were resistant to several of the drugs typically used to treat that pathogen. However, no specimens were resistant to all six antimicrobial drugs.
Using resistance to three or more antimicrobials as the definition of multi-drug resistance, 63% of the bacteria would be classified as multidrug resistant in 2011, compared with 46% in 2010 and 42% in 2009.
"Antimicrobial resistance in veterinary medicine has received a considerable amount of recognition as a potential factor leading to antimicrobial resistance in human medicine," Lubbers said. "However, the contribution of multidrug resistance to limited or failed therapy in veterinary patients has received much less attention."
Because there are a limited number of antimicrobial drugs that can be used for treatment of BRD pathogens, Lubbers said, multidrug resistance in those pathogens poses a severe threat to the livestock industry.
Lubbers said the lab considers this type of information to be part of ongoing disease surveillance.
"The questions of how these bacteria develop or where they come from, how widespread they are, and what is the impact on cattle production are still unanswered," he said.
For more information on the research, listen to the K-State's Ag Today feature by clicking here.