Poultry is one of the world’s fastest growing sources of meat, representing almost 35 % of all the meat produced during 2011 (WATT executive Guide 2011). Currently the industry can produce a broiler chicken ready for the market under six weeks. This is thanks to genetic selection, improved, feeding and health management practices, often involving the use of anti-microbials (AM) as therapeutic agents to treat bacterial disease in intensive farming practices. These antibiotics can be used either in feed or in water.
There has been an increase in bacterial resistance due to the need to use the anti-bacterial medicines.
Anti-microbial resistance (AMR) has become an international topic due to the increase in trends of resistance patterns. Most developed countries put plans and strategies in place to manage AMR. This global problem and its impact on the health of people and animals necessitated the development of the V-Tech Actif ™ plan.
Many anti-microbials are used in animals for metaphylactic treatment. Metapylaxis is the the application of anti-microbial medicines to groups of animals at times when an isolated few animals show symptoms of disease, and it is expected that a large portion of the group will become affected. This type of medication program to a flock of birds reduce overall mortality. It remains a challenge to manage bacterial diseases using narrow-spectrum anti-microbials. Veterinarians are often faced with the challenge to prescribe highly potent, modern antibiotics to effectively treat common conditions that were previously treated with over the counter antibiotics.
Classification of anti-microbial medicines.
1. Anti-microbial drugs developed for human therapy and which are not approved for use in food animals:
- Lipopeptides, Oxazolidinones, Glycopeptides,Carbapenems, Third (or newer) generation tetracyclines (e.g., glycylcyclines) and Fifth (or newer) generation Cephalosporins (e.g., ceftaroline).
2. Critically important antimicrobials:
- Aminoglycosides, cephalosporins (3rd and 4th generation), flouroquinolones, macrolides, penicillans, polymyxins.
3. Highly important anti-microbials:
- Amphenicols, cephalosporins 91st and 2nd generations) lincosides, penicillans, sulphonaimides and combinations, tetracyclines.
4. Important anti-microbials
- Aminocylitols, cyclic polypeptides, nitrofurantoins, nitroimidazoles
For the past 8 years V-Tech undertook to monitor and promote the responsible use of anti-microbials in the poultry industry. The V-Tech Actif™ Plan is comprised of three critical steps to assist in the management of anti-microbial use in Southern Africa:
Once a bacterial disease is diagnosed by a veterinarian, V-Tech requires the submission of swabs from the areas of infection. In order to ascertain the bacterial cause of the infection a swap is submitted to a laboratory for culture. Once cultured the Minimum Inhibitory Concentration (MIC) for various anti-microbials is determined, figure 1.
Figure 1. Mean inhibitory concentration test (Dr TV Rao MD. ‘e’ learning resources for medical microbiologists in Developing world -https://muhammadcank.files.wordpress.com/2010/03/mic-peg.jpg)
These MIC results are of critical importance as they assist the consulting veterinarian and their client to determine the correct anti-microbial to use, to ensure that it is cost effective yet specifically targeted against the cultured bacteria. Figure 2 shows the results as seen in a MIC profile.
Figure 2: MIC profile for a poultry enterprise.
The results are analysed and identify the antibiotic that should best be used. To ensure the correct use of an antibiotic, the guiding principles for prudent use of anti-microbials are applied and verified on all farm operations raising food animals. A sound veterinary overview is important when anti-microbial use is required to maintain the health and welfare of animals. It is also important that the veterinarian takes note of the World Health Organization’s (WHO) characterization of critically, highly and important antimicrobials in human medicine. The choice of antibiotic should follow the decision path from least important for human medicines to important antibiotics.
· Anti-microbials that should not be used and will never be compounded by V-Tech1
· Critically important anti-microbials2
· Highly important anti-microbials3
· Important anti-microbials4
It is imperative once the drug of choice is selected, to ensure that the withdrawal period of the product is adhered to and only included for treatment in the stage of the production cycle, that will allow enough time for withdrawal before slaughter. This is to ensure that residues aren’t present in the final product that is marketed to the consumer and that the meat is safe for consumption.
Once the choice of medication was made an entire monitoring program is implemented. In the case of feed medication feed samples are analysed to confirm that the birds are treated at the prescribed level. This enables monitoring of correct inclusion levels, and to ensure that the medication is included in the correct ration, i.e starter, grower or finisher. The results are monitored very closely and any discrepancies are immediately discussed with the consulting veterinarian, the poultry producer and the feed mill. Same applies to water medication.
The dosage is of critical importance, since incorrect dosing can possibly perpetuate the problem of resistance in poultry, or a treatment that is ineffective for the diagnosed condition. Other problems could also arise in production parameters which could have a detrimental effect on the commercial enterprise. The next step in the monitoring program is the determination of serum levels of birds that are under medication to ensure that the medication reaches effective levels as determined in the MIC of the selected drug. This is crucial to ensure that the therapy is effective. Too low levels would not be effective and are promoting the faster development of resistant bacteria.
Finally, the last step in the Actif™ Plan is the screening of the final animal protein product for any antibiotic residue. This encompasses the involvement of the client, abattoirs and V-Tech. Residue monitoring is critical to ensure consumer safety and has now been established as standard operating practise.
At the abattoirs samples are taken from the liver and muscle for residue testing at a local accredited laboratory and must comply with MRL’s. Maximal Residue Levels (MRL) are published in the government gazette and are compliant with the Codex Alimentarius, an organisation set up by Food and Agriculture Organisation (FOA) and World Health Organisation (WHO). These MRL’s were determined from extensive research, to protect the consumer and ensure safe food standards.
AMR is today’s reality for both human and animal health and one that needs to be taken seriously. Since pathogens have no limit to their boundaries, South Africa is expected to play an important role in this fight against AMR. Veterinarians and other health officials together with companies like V-Tech need to hold hands and work together towards achieving the strategic objectives set out in the AMR strategy framework. It is globally a major concern that antibiotic resistance by organisms are increasing and may limit the availability of effective antibiotics in human medicine in the future.
V-Tech Activ ™ Plan is the answer to Continuous Anti-microbial Sensitivity Profile monitoring.
Dr Shannon Theobald BVSc, MSc (Agric)