Antimicrobial resistance in animals in New Zealand

Antimicrobial resistance in animals in New Zealand

Antibiotics have revolutionised health care both in humans and animals. Their use has reduced pain and suffering, prolonged lives and allowed for procedures (such as complex surgeries) which would not be achievable without them. However, there is increasing discussion internationally and locally about antimicrobial resistance.

There are a number of speakers presenting on this topical issue at the 2014 New Zealand Veterinary Association (NZVA) Conference, being held at Claudelands, Hamilton, from Monday 16 to Friday 20 June.

On Wednesday 18 June
• 11am, Stephen Page, Antimicrobial resistance – The big picture.
• 11.40am, Kate Hill – NZ situation of antimicrobial resistance in companion animals.
• 1.10pm, Andy Millar – NZ situation of antimicrobial resistance in large animals.

On Thursday 19 June
• 8.30am, Scott McDougall – What do we know about antimicrobial resistance in dairy cattle?
• 10am, Scott McDougall – Current prescribing for mastitis.

The following four papers are summarised below.

1 Antimicrobial resistance – companion animals in New Zealand
Kate Hill, PhD Candidate Institute of Veterinary, Animal and Biomedical Sciences, Massey University
Wednesday 18 June, 11.40am.

Considerable attention has focussed on the agricultural use of antimicrobials as a potential public health risk due to the possible evolution and maintenance of drug resistant bacteria. However, more recently, the transmission of multi-drug resistant (MDR) bacteria between people and their pets has been receiving increased attention due to the extremely close relationships people can develop with their domestic pets, and the increase in the standard of veterinary care available.

Currently little is known about MDR bacteria in companion animal populations in NZ. Hill cites, for instance a study by Karen Cooper, Paws, Claws and Udder Things, Gribbles Veterinary Pathology Laboratory which looked at MRSA having been recognised as causing infections in cats and dogs in New Zealand, with seven MRSA isolated in Waikato veterinary diagnostic laboratory in 2005/6. The seven isolates were all of the same strain, which had originally arrived in New Zealand with medical personnel from the UK, and which is now one of the most common hospital-associated strains here.

Hill concludes that the close proximity of humans to dogs and cats, in that many are allowed to sleep in the bedroom, means that transmission of bacteria from people to pets and the reverse is most likely occurring in New Zealand.

She says the veterinary profession must strive to fill the knowledge gap surrounding antibacterial resistance in dogs and cats in New Zealand.

2. Antimicrobial resistance in New Zealand: the situation in production animals
Andy Millar, Synlait Farms Ltd, Rakaia
Wednesday 18 June, 1.10pm

Antimicrobial resistance (AR) is a politically charged subject, and (in addition to impacts on animal welfare and human health) has significant potential to impact on our position on the global market.

Millar argues that domestically, the agricultural sector needs to maintain community licence to operate, and there is a need to assure the general public that use of antimicrobials in production animals is justified and that the risk of AR is being managed appropriately.

He says overall results from New Zealand surveys indicate the current state of AR in New Zealand farm animals is relatively good.
• The levels of resistance in production animals are similar or lower than those reported overseas.
• There is no evidence of increasing prevalence of resistance in food producing animals.
• There is a very low prevalence of resistance to antibiotics of most importance to humans.
• The levels of resistance were lower than in human isolates of the same species over the same time period.
• Antibiotic use, particularly in our pasture based systems, is lower than more intensive systems used in other parts of the world.

Millar says “this is an enviable position to be in and one we should work hard at to maintain.”
The interlinkage of the human ‘microbiome’ with each other and with animals and the environment yields an extremely complex system. Within this, various pathways of transfer of antimicrobial resistance (AR) have been described, yet the level of contribution of these mechanisms to AR in humans is unknown.

He says there remains limited information regarding the prevalence of AR in the production animal population, and there is even less work describing any association between the husbandry procedures used within our farming systems and the emergence of AR. He says accurate understanding of the risk of AR within and emanating from our livestock requires quantitative epidemiological data.

Currently we have information on sales (sales reported) of antimicrobials, patterns of antibiotic resistance in target pathogens, and some purposive survey data investigating resistance in pathogenic bacteria and well as indicator commensal species.

He examines current monitoring activities. Isolates from very young bobby calves, pigs and broiler poultry and Campylobacter, Salmonella, Escherichia coli and Enterococci were included in a 2011 MAF survey.

3. What do we know about antimicrobial resistance in dairy cattle?
Scott McDougall, Cognosco, Anexa Animal Health, Morrinsville.
Thursday 19 June, 8.30am

McDougall’s paper discusses understanding of antimicrobial resistance in dairy cattle and looks at a number of studies here in New Zealand and overseas.
He finds the risk of common bovine pathogens (particularly mastitis pathogens, firstly developing resistance, and secondly being transferred to the human population) appears relatively low.

Use of antimicrobials requires management to reduce these risks. In reaching this conclusion he cites antimicrobial susceptibility monitoring programmes, such as:
• The recent collaboration between ESR and veterinary laboratories to identify Salmonella strains of enteric and commensal pathogens.
• Reports over the past 20 years assessing prevalence of antimicrobial resistance of mastitis pathogens of dairy cattle in New Zealand.

4. Current prescribing for mastitis
Scott McDougall, Cognosco, Anexa Animal Health, Morrinsville
Thursday 19 June, 10am (Dairy cattle stream)

Mastitis is the major indication for use of antimicrobials in dairy cows, with about 85% of doses prescribed for this reason. While there is limited evidence of emerging antimicrobial resistance associated with this prescribing, good stewardship principles suggest that prescription should be based on high probability or evidence of presence of bacterial infection, known sensitivities, knowledge of the pharmacokinetics, and pharmacodynamics of the product being used and likely compliance.

McDougall examines the efficacy of therapies citing studies conducted in New Zealand assessing bacteriological cure rates following treatment of clinical mastitis and use of dry-cow therapy of dairy. He says this gives us confidence around some of the actives currently available on the market.

ENDS

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