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Published: 11 May 2015

Protecting our antibiotics for the future; what are the alternatives?

The Chief Medical Officer, Surrey Honorary Graduate Dame Sally Davies, and the Chief Veterinary Officer, Nigel Gibbens have highlighted Antimicrobial Resistance (AMR) as a priority area. The World Health Organisation (WHO) and World Organisation for Animal Health (OIE) have also stated that without urgent, coordinated action, the world is heading towards a post-antibiotic era, in which common infections of animals and humans may not be treatable.

Professor Roberto La Ragione, Head of the Department of Pathology and Infectious Diseases and Director of the Veterinary pathology Centre in the new School of Veterinary Medicine at the University of Surrey, debates this emerging issue.

Do animals play in a role Antimicrobial Resistance?

Animals may harbour resistant microorganisms in the same way that humans can.  Infections spread from animals to humans or from humans to animals may result in the spread of Antimicrobial Resistance (AMR) and thus prudent use of antibiotics in animals and humans is essential. 

Antimicrobials are used in livestock (farm animals) and companion animals (pets) to treat sick animals, protect healthy animals in contact with sick ones and during periods of transport or similar stresses. However, in some countries they are also used as growth promoters to enhance livestock productivity. The use of antimicrobials as growth promoters has been controversial and thus resulted in an EU-wide ban on the use of growth promoters in 2006.  However, antimicrobial growth promoters continue to be used in some parts of the world and this may be driving some types of resistance.

How can we control Antimicrobial Resistance?

The emergence and spread of Antimicrobial Resistance can be reduced through the sensible use of antimicrobials and education.  This includes responsible prescribing in the medical and veterinary professions and legislation to control access to antimicrobials.  Education of the public is also of paramount importance to ensure that antimicrobials are used appropriately e.g. ensuring patients complete their course of antibiotics and that the most appropriate doses are used.

Prebiotics and probiotics as alternatives to antibiotics

Probiotics are one form of alternative feed supplement, or “functional food” which may be used for prophylaxis in animals and humans. Probiotics can be defined as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host” (FAO/WHO, 2002). There are numerous probiotic products commercially available for humans, pets and livestock.  

Despite their widespread use, it is unlikely that probiotics could be used to treat infections in the same way that antibiotics are used in a clinical setting.  However, probiotics can be used prophylactically and thus significantly reducing the need for antibiotics in animals and humans. Furthermore, some probiotics produce antimicrobial compounds that could be further developed as therapeutic medicines.

Commercial probiotic products available today can be separated into two categories, competitive exclusion products that are defined and those that are undefined. In defined competitive exclusion products, the micro-organisms that compose the product have been identified and may contain individual or combinations of probiotics. In contrast undefined competitive exclusion products, are products where the bacterial cultures are either partially or completely undefined

Probiotics are used widely in farm livestock, companion animals and in aquaculture as they have been shown to reduce clinical disease and increase growth rates. However, the limited understanding of how probiotics function as prophylactic agents means that desirable specific traits remain elusive at present. Moreover, empirical studies are an absolute necessity to identify probiotics which are efficacious prophylactic agents.

Use of prebiotics in animals

Prebiotics are defined as non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon.  They are resistant to digestion in the small bowel so pass to the colon where members of the resident microflora, can ferment them.  Thus, prebiotics can be used in both human and animal hosts to stimulate specific members of the resident microflora to proliferate and subsequently confer potential health benefits to the host. 

In humans prebiotics have been implicated in a range of physiological benefits to the host, specifically, in reducing the incidence of colorectal carcinoma, increasing mineral absorption, improving gastrointestinal barrier function, improving host immune responses, aiding fat metabolism, reducing inflammation of the bowel and reducing the incidence and severity of pathogenic infections.  Furthermore, through stimulating members of the microflora to proliferate, prebiotics can increase the concentration of short chain fatty acids (SCFA’s) present in the host and improve gut health. 

It is clear that alternatives to antibiotics exist and that many of the alternatives could have far reaching health benefits.  However, a consorted effort is required to ensure that alternatives such as pre and probiotics are appropriately tested and marketed.

Professor Roberto La Ragione will be hosting a one day conference on Emerging zoonoses and AMR; A One health approach through multidisciplinary collaboration on Friday 15 May 2015 at The Royal Society of Medicine, 1 Wimpole Street, London W1G 0AE

 

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