This time (18.12.2012 at 8 pm British Time) the Journal Club will be on a publication on the origin of antibiotic resistance:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0034953

I have chosen this paper because it is a topic of public interest and rising awareness on how resistance actually arises and works might help in understanding it in a broader sense. And because it is yet another example that nature has it all, we just have to bother looking for it. 🙂

On the one hand there are arguments and data supporting the theory that the very presence of antibiotics by the use in farming and medicine is the major factor for the appearance of resistance to antibiotics. On the other hand this publication shows that microorganisms sampled from an isolated cave, without contact neither to the surface nor to human influence, show resistance to  current antibiotics on the market. Nevertheless it seems as if both factors are playing an important role in the development of resistance.

The researchers from G. Wrights lab in Hamilton, Canada sampled three different sites of the Lechuguilla Cave (New Mexico, USA) in its most isolated regions (no contact to the surface or humans for 4 million years) and ended up with 93 isolated strains of which 33% were gram negative and 63% gram positive. The bacterial species were identified by 16s rRNA sequencing and were then screened on their resistance towards 26 different antibiotics. After a first screen, the MIC was determined for the positive results as well as testing if an inactivation of the antibiotic had occurred. The researchers also characterised a macrolide kinase from B. paraconglomeratum, which  was one of the isolates that could enzymatically inactivate erythromycin and its semi-synthetic derivative telithromycin. The motivation of this was that the phosphorylation of macrolides is a growing problem in clinical environments. The enzyme from the cave isolate was compared to a surface bacterium of the same genus B. faecium.

Furthermore they discovered two new mechanisms of resistance previously unknown: daptomycin hydrolysis and a macrolide phosphorylation by a MPH class antibiotic kinase (from B. paraconglomeratum).

The authors state, even though the sample number was relatively low, the study nevertheless, points towards the richness of the natural reservoir in “untouched” areas. It is probably not only a source to understand antibiotic resistance found in non-pathogenic bacteria, but also for the discovery of new compounds.

There are some articles from newspaper/National Geographic online about this publication (there are even more under this link, if you are interested http://www.plosone.org/annotation/listThread.action?root=5711 ):

http://www.cbc.ca/news/technology/story/2012/04/13/science-antibiotic-resistant-bacteria.html

http://news.nationalgeographic.com/news/2012/04/120411-drug-resistance-bacteria-caves-diseases-human-health-science

Discussion points:

How was the publication written?

Do you think this pulication gives useful data/arguments to the discussion about the origin of antibiotic resistance?

Would you have liked to see any other experiment?

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