Scientists Urge Caution over Next-Generation Antibiotics

New “damage limiting” drugs intended to alleviate the problems of antibiotic resistance may not be as effective as first thought, a study published in Plos Biology cautions.  By developing a mathematical model, researchers at the University of Edinburgh and Liverpool have found that many of the new drugs being developed that target the symptoms of infection rather than killing pathogens directly, may have unconsidered consequences on the spread of infection and pathogen evolution, especially where symptoms are linked to pathogen transmission.

Treatment through pathogen elimination imposes a strong selection pressure on pathogens for rapid growth and increased drug resistance – an increasingly widespread and concerning problem. In contrast, “damage limiting” drugs aim to reduce pathogen virulence without killing the pathogen, for example by blocking the production of toxins, or treating the damage that they cause. This could reduce illness, and give the immune system time to eliminate the infection itself.

However, the researchers found that there was still ample opportunity for pathogens to evolve, with potentially negative long-term consequences in some cases. In particular, increased pathogen virulence may be selected for, especially in cases where high levels of damage would normally be unfavourable for the pathogen as it might kill the host and reduce the possibilities for transmission. The researchers also cautioned that without eliminating pathogens and by treating symptoms, increasing pathogen densities may be harboured within hosts. This could increase transmission to more susceptible individuals within the population. One of the authors of the study, Dr Pedro Vale, emphasised that whilst “limiting damage may work for the individual, it could, in some cases, increase disease spread.”

Whilst alternatives to conventional antibiotics are urgently needed, this study illustrates that detailed analysis of the long-term consequences of new treatments is required before they can be put into practice.

To access the original study follow this link:

http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001769