Sampling the antibiotic resistome

Remember the soil bacteria Streptomyces I mentioned as being the source of several of our antibiotics? You will probably not be surprised to find that this bacteria is also the source of resistance genes. A paper from the end of 2006 shocked many people though when it was discovered just how many antibioticsStreptomyces was resistant to.

In the paper, they isolated 480 different strains of the bacteria from soil samples and then exposed them to 21 different antibiotics to see if they could survive. The average strain was resistant to between seven and eight antibiotics and two particularly hardy ones were resistant to 15 drugs. The danger is that these genes will pass from harmless soil bacteria such as Streptomyces into more deadly bacteria. This is known to happen, for example the genes that allow some harmful bacteria to resist vancomycin, one of the last lines of antibiotic defense, originally came from soil-dwelling bacteria.

"The chances that these genes will end up in a disease-causing organism at some future point is high," microbiologist Abigail Salyers, University of Illinois at Urbana-Champaign.