(Press-News.org) Bacteria become resistant to antibiotics when stressed, finds research published in BioMed Central's open access journal BMC Evolutionary Biology. In particular E. coli grown at high temperatures become resistant to rifampicin.
It is generally thought that antibiotic resistance is costly to maintain, for example mutations which reduce antibiotic uptake also restrict the amount of nutrients entering the cell. Consequently in the absence of antibiotics non-resistant bacteria will out-compete the resistant ones. However researchers from UC Irvine and Faculté de Médicine Denis Diderot have discovered that by putting bacteria under stress, by growing them at a high temperature, the bacteria could spontaneously develop resistance to the antibiotic rifampicin.
The mutations responsible for rifampicin resistance had different effects in other strains of E. coli. In each type of bacteria tested the mutated subunit of the RNA polymerase rpoB allowed them to grow in the presence of rifampicin, but unlike the original test strain they did not necessarily have a growth advantage at high temperature.
Dr Olivier Tenaillon who led this study commented, "Our study shows that antibiotic resistance can occur even in the absence of antibiotics and that, depending on the type of bacteria, and growth conditions, rather than being costly to maintain can be highly beneficial. Given that rifampicin is used to treat serious bacterial infections such as tuberculosis, leprosy, Legionnaire's disease, and for prophylaxis in cases of meningococcal meningitis, this development has important implications for public health."
These bacteria provide strong evidence that the evolution of antibiotic resistance is governed by two properties of genes, pleiotropy and epistasis. Dr Arjan de Visser from Wageningen University explained, "Pleiotropy describes how the antibiotic resistance mutations affect other functions, hence their fate in other environments. Epistasis describes how well different mutations combine in their effect on resistance, and therefore determines which mutational pathway will be preferred by evolution when several mutations are needed for full resistance."
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Notes
1. Research article
Evolution of Escherichia coli rifampicin resistance in an antibiotic-free environment during thermal stress
Alejandra Rodríguez-Verdugo, Brandon S Gaut and Olivier Tenaillon
BMC Evolutionary Biology (in press)
Commentary
Predicting the evolution of antibiotic resistance
Martijn F Schenk and J Arjan G M de Visser
BMC Biology (in press)
Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central's open access policy.
Article citation and URL available on request on the day of publication.
All images are to be credited to Petra Lundgren, Juan C Vera, Lesa Peplow, Stephanie Manel and Madeleine JH van Oppen.
2. BMC Evolutionary Biology is an open access, peer-reviewed journal that considers articles on all aspects of molecular and non-molecular evolution of all organisms, as well as phylogenetics and palaeontology. @BMC_Series
3. BMC Biology is the flagship biology journal of the BMC series, publishing peer-reviewed research and methodology articles of special importance and broad interest in any area of biology, as well as reviews, opinion pieces, comment and Q&As on topics of special or topical interest. @BMC_Series
4. BioMed Central is an STM (Science, Technology and Medicine) publisher which has pioneered the open access publishing model. All peer-reviewed research articles published by BioMed Central are made immediately and freely accessible online, and are licensed to allow redistribution and reuse. BioMed Central is part of Springer Science+Business Media, a leading global publisher in the STM sector. @BioMedCentral
'Stressed' bacteria become resistant to antibiotics
2013-02-22
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