Page 6 - Australian Pork Newspaper

Tackling antimicrobial resistance at a global level
IN September 2016 the United Nations an- nounced a global pro- gram to tackle antimi- crobial resistance.
For the first time, Heads of State commit- ted to taking a co-or- dinated approach to ad- dress the root causes of antimicrobial resistance across multiple sectors, especially human health, animal health and agri- culture.
This is only the fourth time a health issue has been taken up by the UN General Assembly (the others are HIV, noncom- municable diseases and Ebola).
Support for the resolu- tion was unanimous.
It signalled an unprec- edented level of atten- tion to curb the spread of infections resistant to antimicrobial medicines.
It recognised the seri- ous global challenge to health, food security and development.
No one country, sector or organisation could ad- dress this issue alone.
Countries reaffirmed their commitment to develop national action plans on antimicro- bial resistance based on
the ‘Global Action Plan on Antimicrobial Resist- ance’ – developed by the World Health Organi- zation in co-ordination with the Food and Agri- culture Organization of the United Nations and the World Organization for Animal Health.
Antimicrobial resist- ance is driven by numer- ous complex factors but overuse, misuse and irra- tional use are the leading causes.
One of the solutions, therefore, is to promote more responsible use of antimicrobials among populations.
The Australian live- stock industries have a long history of address- ing antimicrobial resist- ance.
Their previous and on- going work – a result of partnerships across the animal sectors – has re- sulted in relatively low levels of antimicrobial resistance in our food animals.
As part of its global obligations, Australia re- leased its First National Antimicrobial Resist- ance Strategy 2015-19.
One of the objectives re- quires us to implement ef-
fective antimicrobial stew- ardship practices across human health and animal care settings to ensure the appropriate and judicious prescribing, dispensing and administering of an- timicrobials.
In support of the na- tional plan, the livestock sectors have developed antimicrobial resistance plans.
These embrace the ideas of responsible use, reduction in usage and antimicrobial resistance surveillance.
The consequences of failing to be part of the global program are the risks to human, ani- mal and environmental health, trade sanctions and consumer activism.
Just to ram home the points, while resistance to some antimicrobials used in pigs has changed little in 40 years, com- mon pathogens such as actinobacillus pleuro- pneumoniae (APP) and brachyspira hyodysente- riae (B. hyo) are quietly building resistance.
For example, tilmicosin (Pulmotil, for example) used to be a very reliable treatment against APP and tiamulin was similar-
ly effective against B. hyo. Unfortunately, it’s no longer as true as it once
was.
Recently, the Austral-
ian Veterinary Associa- tion and Animal Medi- cines Australia, with support from the Com- monwealth Department of Agriculture and Water Resources and Austral- ian Pork Limited, re- leased the antimicrobial prescribing guidelines for pigs.
It can be accessed via the APL website australi- anpork.com.au
The guidelines were written by an expert group including a mi- crobiologist (Prof Glenn Browning), an infectious disease specialist (As- soc Prof Jacqui Norris), a clinical pharmacologist (Dr Stephen Page) and veterinarians working in the field of pig medicine (Dr Bernie Gleeson and Dr Ross Cutler).
As part of this global effort, Australian Pork Newspaper, in associa- tion with APL, presents a new regular column by Dr Cutler about safely reducing antimicrobial usage on Australian pig farms.
Figure 1: Grow-finish mortality rate per week.
Reducing antimicrobial use for respiratory disease in growing pigs: A case study
TO combat a serious and sustained increase in res- piratory disease, a farm’s health team made signif- icant environmental and pig flow changes.
Vaccination schedules were modified.
As a consequence, aver- age antimicrobial use was reduced from 92 doses per 100kg liveweight at the peak of the outbreak to 6.2 doses (1.7 injectable doses and 4.5 in-water doses).
The farm now uses no in-feed medication but
does medicate from time to time in water.
Respiratory disease is well controlled and grow- finish mortality rate has been stable at about 2 per- cent for the past two years. The farm
Pigs arrived at the farm at 12 weeks of age and were grown through to market weight.
They experienced chal- lenges of infection with mycoplasma and actino- bacillus pleuropneumo- niae (APP).
Piglets were vaccinated
against mycoplasma. Groups of pigs were de- livered to the site each
week and sold by weight. The mortality rate for this site varied between 2 percent and 4 percent, with seasonal ‘spikes’ to
6 percent.
The issue
Coughing and ill-thrift affected 10-20 percent of different groups in the growing and finishing phase.
In-feed medication (chlortetracycline and ty- losin) was used for a to- tal of 63 days out of the 84-day placement for the average pig in the growing and finishing phase prior to mid-2012.
This equated to about 50 antimicrobial doses per 100kg liveweight for pigs at this farm.
Group water medication (amoxicillin or tilmicosin) and individual injectable medication (penicillin or florfenicol) were also used if clinical signs were severe.
This resulted in an ex- tra eight to 10 doses per 100kg liveweight, lead- ing to average antimicro- bial usage of 59 doses per 100kg liveweight.
In mid-2012 the mortal- ity rate spiked at close to 12 percent.
To control the mortality rate, the level of antimi- crobial use was increased.
Further medications were added to feed and the frequency of water dosing was also increased.
These measures in- creased the average anti- microbial use to 92 doses per 100kg liveweight.
This increased level of medication continued through to mid-2013, but the mortality rate in- creased again to 6 percent (Figure 1).
Post mortems and cul- tures revealed mixed in- fection with APP, P. mul- tocida and S. suis.
Lungs were PCR posi- tive for M. hyopneumo- niae.
Serology profiles of the population revealed se- roconversion to both M. hyopneumoniae and APP peaked around 15 weeks of age.
Until mid-2014, the number of pigs placed each week in the system varied from 452 to 2216.
The temperature set- tings for ventilation con- trol varied between sheds
☛ continued P7 www.porknews.com.au
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Page 6 – Australian Pork Newspaper, May 2019