Aggressive drug therapy aids superbug evolution

August 4, 2011

Public release date: 3-Aug-2011

Contact: Archibald

christina.chant@...

Queen's University

Aggressive drug therapy aids superbug evolution

New research raises troubling concerns about the use of aggressive drug

therapies to treat a wide range of diseases such as MRSA, C. difficile,

malaria, and even cancer.

" The universally accepted strategy of aggressive medication to kill all

targeted disease pathogens has the problematic consequence of giving any

drug-resistant disease pathogens that are present the greatest possible

evolutionary advantage, " says Troy Day, one of the paper's co-authors

and Canada Research Chair in Mathematical Biology at Queen's.

The researchers note that while the first aim of a drug treatment

program should be to make and keep a patient healthy, the patient's

immune system also has to be allowed to work.

They suggest several strategies to address the challenge of

drug-resistant pathogens including improving the current knowledge base,

discovering effective ways for slowing the spread of drug-resistant

pathogens from person-to-person, and developing strategies for

preventing drug-resistant mutations from occurring in the first place.

Last century's malaria wonder drug, chloroquine, is a perfect example of

aggressive medication leading to the growth of drug-resistant pathogens.

Since drug-resistant malarial parasites didn't have to compete with

parasites that were killed off by an aggressive chloroquine treatment

plan, the resistant parasites were given an evolutionary advantage. As a

treatment for malaria, chloroquine is now useless across most of Africa.

" As things currently stand, no research exists that can tell us what the

optimal drug delivery strategy would be for maintaining treatment

effectiveness and mitigating the evolution of resistance, " says Dr. Day.

" While overwhelming medicinal force may sometimes be required, we need

to be clear about when and why this strategy should be chosen since it

brings with it some very clear problems with respect to resistance

evolution. "

###

This research was conducted in collaboration with Read and Silvie

Huijben at Pennsylvania State University and was published in a recent

issue of the Proceedings of the National Academy of Sciences.

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