Detection of tetracycline resistant bacteria in ecologically disturbed environments

Through a variety of potential mechanisms bacteria resistant to tetracycline are gaining access to natural systems. Through direct isolation and molecular techniques, the presence of bacterial resistance to tetracycline in two sub-watersheds of the Chesapeake Bay was examined. Water samples were taken from the Anacostia and Chester River systems and plated onto nutrient agar infused with tetracycline (10mug ml-1). Isolates resistant to tetracycline were found at all Anacostia and Chester River sites. Samples were analyzed for the presence of eight tetracycline resistant genes. DNA analyses revealed isolates from all four sites of the Anacostia River system contained the tet(B) gene however no Tet genes were found in Chester River isolates. Using filter-sterilized water from an Anacostia site and nutrient broth, one tet(B) positive isolate was grown in the presence and absence of tetracycline (10mug ml-1). This isolate demonstrated similar growth patterns in both the filtered Anacostia water and nutrient broth.