Page 14 - National Poultry Newspaper

Page 14 – National Poultry Newspaper, June 2019
☛ continued P15 www.poultrynews.com.au
Antimicrobial stewardship – the path to least resistance
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ANTIMICROBIAL re- sistance is now accepted as a global public health priority and an impor- tant emerging animal health issue.
Antimicrobial use con- tributes to the selection of antimicrobial resist- ance and consequently only necessary high- quality use of antimicro- bial agents is considered appropriate.
The Australian meat chicken and egg indus- tries are historically low users of antimicrobial agents and recent surveys of antimicrobial resist- ance in bacterial com- mensal species isolated from meat chickens and the environment of laying sheds have revealed very low levels of antimicro- bial resistance.
Despite this very fa- vourable position, the implementation of for- mal and systematic an- timicrobial stewardship plans will support the continued low frequency of antimicrobial use and antimicrobial resistance. Introduction
Antimicrobial resist- ance is considered one of the biggest threats to human and animal health today and all users of antimicrobial agents have a responsibility to ensure
these agents are only used when necessary.
The Australian poultry industry takes the issue of AMR very seriously and has a long history of developing and introduc- ing initiatives to enhance infection prevention and control and to encourage restriction of antimicro- bial use to essential situ- ations.
The codes of practice and guidelines intro- duced progressively since the 1980s have evolved into the antimicrobial stewardship plans of the 2000s.
AMS and good stew- ardship practice concerns much more than just judi- cious or prudent use of antimicrobial agents.
Indeed, the current fo- cus is on continuous im- provement and ways to refine, reduce and replace antimicrobial use while maintaining the highest standards of bird health, allowing close align- ment with the Australian and global strategies for AMR and antimicrobial use minimisation. Antimicrobial steward- ship
The long history of conservative regulation and use of antimicrobial agents in the Australian poultry industry has re-
sulted in the unique situ- ation where many of the critically important an- timicrobial classes used widely in poultry pro- duction outside Australia have never been avail- able.
For example, the focus of the British Poultry Council AMS program has been the reduction or elimination of the use of fluoroquinolones, third-generation cepha- losporins and colistin – all antimicrobial classes never approved for use in Australian poultry.
Thus, Australian AMS programs can focus on more advanced aspects of stewardship.
However, the aims of Australian AMS coincide with those of the British and there is great conflu- ence with the statement of BPC Chairman John Reed who concluded af- ter reviewing the 2017 AMS program that “Our farmers and veterinarians need antibiotics in their toolbox to treat sick birds – zero use is not an option – and we will protect the health and welfare of our birds. We will safeguard the efficacy of antibiot- ics as part of sustainable food production, and we will continue to feed the nation.”
But what is AMS?
One of the clearest de- scriptions is that provid- ed by Guardabassi and Prescott who define AMS as “the multifaceted and dynamic approaches required to sustain the clinical efficacy of anti- microbials by optimising drug use, choice, dosing, duration and route of ad- ministration, while mini- mising the emergence of resistance and other ad- verse effects”.
That AMS is multifac- eted means it is complex and involves many ele- ments and requires clear thinking.
The dynamic approach reflects the fact that, just like AMR, AMS is not a stationary practice; it is forever changing and the direction of change, espe- cially that of continuous improvement, is guided by the multifaceted AMS team.
Optimising drug use, choice, dosing, duration and route of administra- tion is very challenging as it is inevitably not a fixed and predictable equation, it does not mean ‘one dose suits all’; each cir- cumstance may require a different approach, which may also include no anti- microbial use.
Minimising the emer- gence of AMR is a neces- sary and demanding goal, but one for which there is insufficient guidance.
Only by monitoring re- sponses to treatment or non-treatment and un- dertaking surveillance of AMR can any insight into resistance minimisation be gleaned.
The 5R framework for A MS was developed to provide a systematic and comprehensive approach to AMS planning, imple- mentation and monitor-
ing to allow a potentially complex process to be both practical and effec- tive.
The 5Rs include respon- sibility, review, refine, re- place and reduce.
AMS is a continuous process with a goal of de- fining and applying best practice, AMR minimisa- tion and optimal control of animal health.
Good stewardship prac- tice describes the devel- opment, implementation and continuous improve- ment of the AMS plan.
The first Australian Veterinary Antimicro- bial Stewardship AMS Conference was held in November 2018 and pro- vided a comprehensive overview of the current situation and initiatives introduced by the vari- ous livestock industries as well as actions and plans in companion ani- mal practice. Antimicrobial resist- ance
Supported by funding from the Australian De- partment of Agriculture and Water Resources, the Australian Chicken Meat Federation recently published the results of a national study of surveil- lance for AMR in enteric commensals and patho- gens in Australian meat chickens.
The study was compre- hensive and followed in- ternational standards for design and analysis.
Importantly, it was ob- served that resistance to antimicrobials consid- ered of critical impor- tance to human health was very low in commen- sal bacteria from Austral- ian meat chickens – high- lighting the effectiveness of past and present AMS initiatives.
Two examples dem- onstrate the stark con- trast in resistance levels in Australia with those elsewhere, for example comparing results from Australia with those from the EU and UK.
EFSA and ECDC pub- lished the EU summary report on AMR in zo- onotic and indicator bac- teria from humans, ani- mals and food in 2016.
With respect to campy- lobacter, for the 3117 campylobacter jejuni iso- lates from broilers report- ed by 24 member states, the overall observed level of resistance to cipro- floxacin was 66.9 percent and to nalidixic acid 61.7 percent.
In the UK, ciproflox- acin resistance was re- ported in 40.6 percent of C. jejuni isolates from broilers.
These results contrast with those observed in the Australian study where only 14.8 percent of C. jejuni were found to carry ciprofloxacin re- sistance.
This low level of resist- ance was unexpected and the first report of such resistance in C. jejuni isolated from Australian poultry.
Fluoroquinolones (the class to which ciprofloxa- cin belongs) have never
been approved for use in Australian livestock in- cluding poultry.
The finding of FQ re- sistance is highly unlike- ly to be the result of FQ use in poultry, rather the appearance of this resist- ance may ultimately be found to have arisen in humans and subsequently transferred to poultry – highlighting the need for vigilance and the need for biosecurity to encompass poultry workers.
The second example of contrasts between resist- ances found in Australia and elsewhere relates to E.coli.
None of the E. coli isolates from Austral- ian poultry demonstrated resistance to ceftiofur, colistin, florfenicol, chloramphenicol or gen- tamicin.
Two isolates (1 percent) demonstrated reduced susceptibility to cipro- floxacin but these isolates were not considered clini- cally resistant.
In the UK, resistance to the FQ ciprofloxacin was observed in 21.6 percent of E. coli isolates recov- ered from caecal contents of healthy broilers at slaughter.
In the European Un- ion, EFSA and ECDC reported “for broilers, the highest overall resist- ance levels observed in the reporting MSs were to the quinolones, that is, nalidixic acid (59.8 per- cent) and ciprofloxacin (64 percent), and to am- picillin (58 percent), sul- famethoxazole (49.9 per- cent), tetracycline (47.1 percent) and trimetho- prim (40.7 percent).
Levels of resistance to the third-generation cephalosporins, cefotaxi- me and ceftazidime, were similar at 4 percent and 3.6 percent, respectively.”
A proof-of-concept AMR study of salmonel- la isolates obtained from Australian layer shed en- vironments has also re- cently been completed.
The susceptibility of 307 isolates collected over the period 2015 to 2018 was assessed against a panel of 16 an- timicrobial agents.
Overall, a very low fre- quency of resistance was observed.
Remarkably, 295 iso- lates (96.1 percent) dis- played no evidence of phenotypic resistance to any tested antimicrobial, while eight, one and two isolates were respective- ly resistant to one, two or three antimicrobial agents.
The enviable status of Australian poultry meat with respect to AMR was supported by the recent publication of McLellan et al. (2018) who found no evidence of acquired multidrug resistance in gram-negative bacteria isolated from raw chick- en drumsticks obtained from 30 retail outlets in Melbourne.
Conclusion
The progressive intro- duction by the Austral- ian poultry industry over