Therapy alternative to farm animal antibiotics

Despite longstanding scientific concerns, antibiotics continue to be given to farm animals as a means of producing leaner meat. This helps to spread antibiotic resistance. A new type of therapy offers an alternative.

One concern with parts of the farming industry is the indiscriminate use of antibiotics for farm animals, with the intention of producing better quality meat from animals like cows and pigs (there is a secondary reason, which relates to treating animal infections). Microbiologists have expressed concerns over this practice since it represents a significant contributor to the spread of antimicrobial resistance in human society. For example, farm workers who work on farms where high levels of antibiotics are used in farm animals carry a high proportion of antibiotic resistant bacteria compared with farms that are antibiotic-free.

There are several alternative to the use of antibiotics for animals. These include probiotics, prebiotics, oligosaccharides, antimicrobial peptides and essential oils. However, things called phages are beginning to to receive increased attention.

To come up with an alternative to the practice, scientists based at Leicester University have demonstrated that it should be possible to develop an alternative therapy to tackle diseases in pigs. This is based on bacteriophages.

Bacteriophages are viruses that infect (through injection of the viral genome into the bacterial cell cytoplasm) and can kill bacteria. One reason form looking closely at bacteriophages is because of their special characteristics, including widespread distribution, self-replication and a lack of effects on the normal microflora of any treated animals.

The lead researcher, Professor Martha Clokie has recently presented results to a pig industry meeting in Solihull. Speaking with the BBC, the researcher states that based on the early results phage therapy could, one day, be extended from pigs to humans and this would be "completely transformative for human health".

The academic adds: "There are many infections that we just can't treat with antibiotics because they have become resistant to them. So using the phage therapy for specific diseases could change the way we treat infection. It could give us a whole new armoury." This follows Professor Clokie and her team identifying a range of disease-killing phages. The research was funded by the U.K. based Agriculture & Horticulture Development Board.

In related, although more troubling antimicrobial news, Nature reports how eighteen months ago a gene that confers resistance to colistin (which is known as an ‘antibiotic of last resort') merged in bacteria isolated from pigs in China. Since this first case was reported, the resistance gene, termed mcr-1, has been found around the world at an rapidly accelerating rate.

Posted by Dr. Tim Sandle