A recent report from Science details how hundreds of soil-borne bacterial isolates are not only able to thrive under antibiotics conditions but are able to in fact utilize the antibiotics as their sole carbon source. The study demonstrates an unappreciated reservoir of antibiotic-resistance determinants within hundreds of bacterial isolate that were found in at least 11 diverse soil types.


Here is the reference and abstract-


Gautam Dantas, Morten O. A. Sommer, Rantimi D. Oluwasegun, George M. Church. Bacteria Subsisting on Antibiotics. Science 4 April 2008: Vol. 320. no. 5872, pp. 100 - 103
DOI: 10.1126/science.1155157

Abstract:
Antibiotics are a crucial line of defense against bacterial infections. Nevertheless, several antibiotics are natural products of microorganisms that have as yet poorly appreciated ecological roles in the wider environment. We isolated hundreds of soil bacteria with the capacity to grow on antibiotics as a sole carbon source. Of 18 antibiotics tested, representing eight major classes of natural and synthetic origin, 13 to 17 supported the growth of clonal bacteria from each of 11 diverse soils. Bacteria subsisting on antibiotics are surprisingly phylogenetically diverse, and many are closely related to human pathogens. Furthermore, each antibiotic-consuming isolate was resistant to multiple antibiotics at clinically relevant concentrations. This phenomenon suggests that this unappreciated reservoir of antibiotic-resistance determinants can contribute to the increasing levels of multiple antibiotic resistance in pathogenic bacteria.