Find in Library

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to describe a novel trimethoprim resistance gene cassette, designated <it>dfrA30</it>, within a class 1 integron in a facultatively oligotrophic, multiple antibiotic and human serum resistant test strain, MB45, in a population of oligotrophic bacteria isolated from the river Mahananda; and to test the efficiency of surface bound acetate on zinc oxide quantum dots (ZnO QDs) as bactericidal agent on MB45.</p> <p>Methods</p> <p>Diluted Luria broth/Agar (10^-3) media was used to cultivate the oligotrophic bacteria from water sample. Multiple antibiotic resistant bacteria were selected by employing replica plate method. A rapid assay was performed to determine the sensitivity/resistance of the test strain to human serum. Variable region of class 1 integron was cloned, sequenced and the expression of gene coding for antibiotic resistance was done in <it>Escherichia coli </it>JM 109. Identity of culture was determined by biochemical phenotyping and 16S rRNA gene sequence analyses. A phylogenetic tree was constructed based on representative trimethoprim resistance-mediating DfrA proteins retrieved from GenBank. Growth kinetic studies for the strain MB45 were performed in presence of varied concentrations of ZnO QDs.</p> <p>Results and conclusions</p> <p>The facultatively oligotrophic strain, MB45, resistant to human serum and ten antibiotics trimethoprim, cotrimoxazole, ampicillin, gentamycin, netilmicin, tobramycin, chloramphenicol, cefotaxime, kanamycin and streptomycin, has been identified as a new strain of <it>Klebsiella pneumoniae</it>. A novel <it>dfr </it>gene, designated as <it>dfrA30</it>, found integrated in class 1 integron was responsible for resistance to trimethoprim in <it>Klebsiella pneumoniae </it>strain MB45. The growth of wild strain MB45 was 100% arrested at 500 mg/L concentration of ZnO QDs. To our knowledge this is the first report on application of ZnO quantum dots to kill multiple antibiotics and serum resistant <it>K. pneumoniae </it>strain.</p>