Field of Science

Bacteria that use antibiotics...for food!

ResearchBlogging.orgAntibiotic resistance is by now a well-known phenomenon. Resistance is carried in both antibiotic producing bacteria to protect themselves from their own weaponry, and the soil bacteria they attack, in an attempt to defend themselves. The sudden influx of pharmaceutical antibiotics has encouraged the spread of resistance to human pathogenic strains, leading to the so-called 'superbugs' seen in the media such as MRSA and vancomycin-resistant C. difficile.

However researchers at Harvard found that not only are some bacteria able to neutralise the threat of antibiotic resistance, they actually use antibiotics as a food source. Not only that, but they were capable of using antibiotics as the sole carbon source. The table below (taken from the reference at the end of the post) shows the survival of bacteria on antibiotics using samples from three different types of soil, Farmland (F), Urban (U) and Pristine (P - soil from non urban areas with minimal human contact for 100 years):

The antibiotics used include natural, synthetic and semi-synthetic molecules, all all of which could be used by bacterial species as a carbon source. Even more interestingly (or alarmingly) the antibiotics were at concentrations of 1g/litre, 50 times higher than the concentration normally used to test for resistance.

The 'pristine' soil is the one that the researchers found the most interesting, as the general expectation was that this area would contain fewer antibiotic-eating bacteria, having had minimal interaction with people and pharmaceutical antibiotics. However the data showed no noticeable difference, despite not being in contact with human-designed antibiotics, the bacteria are meeting plenty of bacterial-based antibiotics, and adapting to use them for food.

The big question of course is Will it Spread? Around the quarters of the isolated strains belonged to orders containing clinically relevant strains such as Salmonella and E. coli, meaning that hypothetically at least antibiotic consumption should be able to spread. On the other hand, actual consumption of antibiotics is unlikely to provide a greater evolutionary advantage than just resistance, and will confer a larger metabolic load on the bacteria. Although the pathways of antibiotic metabolism have not yet been fully determined, the first few steps seem to be similar to well-known resistance mechanisms (particularly in penicillin consumption). One conclusion, therefore, is that only part of the metabolic pathway would be (or already has been) passed on to pathogenic organisms, enough to provide resistance without placing unnecessary metabolic burdens on the cell.

Hat tip to Byte Size Biology for alerting me to the paper.

--

Dantas, G., Sommer, M., Oluwasegun, R., & Church, G. (2008). Bacteria Subsisting on Antibiotics Science, 320 (5872), 100-103 DOI: 10.1126/science.1155157

6 comments:

rhan said...

Wow. That's on par with staphylococcus hijacking your complement system and primary immune response to create its happy little ball of immune-proof necrotic tissue.

Honestly, I can't say I'm surprised to hear this, given the evolutionary probability of antibiotic metabolism by certain species being transferred horizontally. So dangerous, but sooo coool!

Lab Rat said...

Yeah...once I'd got over being surprised about it, I did sort of reralise it wasn't that surprising :) After all, bacteria will eat anything; sulfur, concrete, explosive waste even. Given that soil bacteria naturally produce a range of antibiotics, I suppose it was only a matter of time before they found bacteria that could eat them.

Kelsey said...

Lab Rat, you've made little things (like bacteria) cool. For that, and for being an awesome blogger, we're giving you a Kreativ Blogger award. Congratulations! You can learn all about the award on our blog. http://maukamakai.wordpress.com/2009/10/01/kreativ-blogger/

R2K said...

: )

Jim said...

In case you haven't spotted it yet. Dave Munger of Cognitive Daily referenced you in his latest Seed Magazine article ;-)

Term Papers said...

The antibiotics used include natural, synthetic and semi-synthetic molecules, all all of which could be used by bacterial species as a carbon source,certainly Bacterias are harm full for humans health.


Term papers