full issue - Association of Biotechnology and Pharmacy

Current Trends in Biotechnology and PharmacyVol. 5 (1) 1054-1059 January 2011. ISSN 0973-8916 (Print), 2230-7303 (Online)those in clinical pathogens (7). These strains,producers of the aminoglycosides: kanamycin andneomycin, were capable of drug modification byacetylation and phosphorylation, respectively, asa means of self-protection (7).In the late 1990s, Gerard Wright and histeam demonstrated that the mechanism ofvancomycin resistance in vancomycin-producingsoil bacteria was identical to the mechanism thatemerged in vancomycin-resistant enterococci(VRE) in the late 1980s (8). Hence they suggestedextending the scope of studies on antibioticresistance to include bacterial species that arenever pathogens and may not even be in the“human” sphere. Although this study does notprovide evidence for the direct transfer ofresistance elements from the soil resistome topathogenic bacteria, it identifies a previously underappreciated density and concentration ofenvironmental antibiotic resistance. The level anddiversity of resistance uncovered in this work islikely to be substantially higher than what this studyreveals as the present study is restrictedexclusively to culturable bacteria, which representonly a fraction of soil-dwelling bacteria. Forexample, a recent soil metagenome analysisuncovered several aminoglycoside resistancegenes in uncultured organisms (9). As a whole,the study of resistance in soil bacteria is rapidlygaining recognition as an important reservoir fromwhich many clinical parallels can be drawn. Thisunexpected conclusion should have a paradigmshifting impact on our understanding of thejudicious use of antibiotics and the drug discoveryprocess. The present study also raises questionsabout protein evolution and gene transfer amongbacteria. However, these are early days for studieson resistome and there are yet major problems tobe tackled.Extensions of this work will includeanalysis of soils from diverse geographicallocations and resistance to other antibiotics. In1058addition, studies of the genetic diversity andstructure of bacterial antibiotic resistance proteinsmay eventually lead to the design of compoundsthat inhibit resistance mechanisms, thus extendingthe useful lifetime of currently availableantibiotics. Secondly, as genes for antibioticresistance are often clustered with genes forantibiotic biosynthesis (10), antibiotic resistancestudies may lead to the discovery of biosyntheticpathways encoding potentially novel antibiotics(11). It is not known whether antibiotic resistancegenes move readily from environmental reservoirsto clinical settings, but future work should considerthe potential contributions of soil bacteria to theproblem of antibiotic resistance. The survey ofantibiotic resistance mechanisms can assist theelucidation of novel mechanisms that may emergeclinically, as well as serve as a foundation fornew antibiotic development. An emphasis hastherefore been placed on educating doctors andnational governments relative to restrictingantibiotic usage to those cases where humanhealth is threatened by virulent pathogens.AcknowledgementsThe authors wish to thank the help renderedby Ms. Aruna during the initial isolation of thebacteria used in the study. The authors gratefullyacknowledge the funding received in the form ofDST-SERC FAST Track Scheme (NO. SR/FT/LS-143/2008).Competing interests: None declaredEthical approval: Not requiredReferences1. D’Costa, V.M., Griffiths, E., Wright, G.D.(2007). Expanding the soil antibioticresistome: exploring environmental diversity.Curr. Opin. Microbiol., 10: 481-89.2. Bager, F., Madsen, M., Christensen, J.,Aarestrup, F.M. (1997). Avoparcin used asa growth promoter is associated with theInvestigations on Microbial Resistance among Bacteria Dwelling in Indian Soils