A couple of years ago in "The Microbes Win", Acronym Required wrote about research done by Wright et al at McMaster University, who found that many species of microbes isolated from soil samples had significant antibiotic resistance to clinically useful antibiotics. Last week researchers at Harvard published a study in the journal Science (Dantas et al, "Bacteria Subsisting on Antibiotics":Vol. 320. no. 5872, pp. 100 - 103), advancing research in this area a step further.
The scientists managed to culture a significant number of soil isolates using antibiotics as the sole source of carbon. The bacteria that proliferated most proficiently on a diet of antibiotics were from the Pseudomoniale and Burholderiale orders. Bacteria in the genuses Pseudomonas or Burkholderia, like Pseudomonas aeruginosa and Burkoholderia cepacia are responsible for infections involved in meningitis, skin, lung and bone infections, swimmer's ear, and opportunistic infections in immunocompromised patients and those afflicted with cystic fibrosis.
The Harvard group suggest that the large genomes of Pseudomonas and Burkholderia species give them many diverse mechanisms of resisting bacteria and adaptive versatility, and that catabolism of antibiotics is just one tool in their arsenal of antibiotic resistance mechanisms.
These bacteria are very relevant clinically but scientists haven't observed utilization of this antibiotic catabolism, probably because there are many sources of carbon at infection site therefore catabolism of antibiotics isn't the most useful method of resistance. Since soil residing bacteria are exposed to natural sources of antibiotics, the research isn't extremely surprising, but may lead to further understanding of shared and unique antibiotic resistance mechanisms.
