BRD surveillance project underway

17 September 2018

Research is underway to determine the status of antimicrobial resistance for bovine respiratory disease (BRD) pathogens in Australian feedlot cattle, to help the industry maintain the effectiveness of its registered antimicrobials.

The Meat & Livestock Australia (MLA) project, funded by grainfed levies in consultation with the Australian Lot Feeders’ Association (ALFA), will see a pilot surveillance of resistance of BRD pathogens to common veterinary antimicrobials conducted across a number of Australian feedlots in 2018-19.

Professor Darren Trott at the University of Adelaide is leading the project, which is also developing easy-to-use sample collection procedures for feedlots and their consulting veterinarians to use in conducting their own in-feedlot antimicrobial surveillance programs.

Professor Trott said it is important to develop guidelines to prevent contamination when collecting lung tissue samples and swabs for testing.

“These bacteria are quite fastidious and if you get skin or gut bacteria on to the sample, it makes it very difficult to test,” Professor Trott said.

“Not a lot of Australian feedlots go to the trouble of opening up a carcase, taking a sample and sending it to a veterinary diagnostic laboratory, because we have low rates of BRD and they generally see a response to treatment for BRD.

“Testing is usually only done as a disease investigation, not as routine surveillance, however, if we can encourage increased surveillance, we can hopefully prevent what’s happening in the North American feedlot industry right now, where we’re seeing an alarming trend for multi-drug resistant (MDR) BRD pathogens.”

Professor Trott said while the Australian feedlot industry was very different to the North American industry, Australia must learn from North America and not induce antimicrobial resistance in BRD pathogens by misuse or overuse of antimicrobial agents.

“Our feedlots have a reduced stocking density, we do a lot of backgrounding and preventative vaccination, we have much lower rates of BRD and we use antimicrobials sparingly compared to North America. Further, Australia is the only country in the world that has not allowed the use of antibiotics known as fluoroquinolones in the food production system.”

Professor Trott said the surveillance project in Australia would develop a large representative collection of BRD pathogens including Mannheimia hemolytica, Pasteurella multocida, Histophilus somni and potentially, Trueperella pyogenes.

“There is active surveillance at a number of feedlots but any feedlot is welcome to submit samples to participating veterinary diagnostic laboratories to add to the data,” Professor Trott.

“Collaboration with veterinary diagnostic labs in Queensland (Department of Agriculture and Fisheries), NSW (EMAI and CSU) and Victoria (ACE laboratories) will make BRD pathogen isolates available to the project for antimicrobial resistance testing.

“We really need to collect at least 30 isolates per bacterial species per year to have a good representative sample.

“There are three parts to the surveillance – a retrospective collection spanning 2014 to 2017, and then the 2018 and 2019 collections.

“The aim is that we will get three sets of data to prove our hypothesis that there has been no development of resistance to key veterinary drugs in that time.”

MLA Feedlot Project Manager, Dr Joe McMeniman, said MLA has been working closely with ALFA on antimicrobial stewardship initiatives and the surveillance project is the next step in the collaboration.

“In March, the Antimicrobial Stewardship Guidelines for the Australian Cattle Feedlot Industry were released. A key part of the guidelines is antimicrobial resistance monitoring through surveillance,” Dr McMeniman said.

“Antimicrobial resistance monitoring and surveillance is the yardstick whereby the successful implementation of antimicrobial stewardship principles is effectively measured. It is important that surveillance of pathogens and the antimicrobial sensitivity of these pathogens to antimicrobials on the prescribed drug list are regularly assessed.

“We encourage feedlots to work with their consultant veterinarian to implement an antimicrobial stewardship plan. An important part of that plan is regular surveillance of pathogens and the antimicrobial sensitivity of these pathogens to antimicrobials on the prescribed drug list.

“For example, a surveillance program could be undertaken during the typical months where cases of BRD occur (autumn and spring), involving post-mortem of both treated and untreated pen deaths and aseptic collection of lung tissue samples or swabs for culture and susceptibility testing.

“The feedlot veterinarian is encouraged to develop, coordinate and implement the monitoring and surveillance program in conjunction with the feedlot manager. Samples should be sent to a certified diagnostic laboratory for pathological examination, culture and sensitivity.

“It is an important role for the consulting veterinarian to be involved in the interpretation of the results, and to ensure that they are used where applicable to further refine use and take preventative measures.”


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