Antibiotics are frequently used in aquaculture for the treatment of bacterial diseases. In this study, bacteria were isolated from the spleen, liver and kidney of grouper from PCG and cobia from EMD and THOD in southern Taiwan. All isolates were cultured on TCBS agar, blood agar, and MacConkey agar. The results showed that the isolates from PCG were 83% (20/24) Vibrio and 13% (3/24) £]-hemolysis¡F76% (22/29) Vibrio and 24% (7/29) £]-hemolysis from EMD¡F100% (6/6) Vibrio and none of £]-hemolysis from THOD. The bacteria were tested for antibiotics resistance by the disc agar diffusion method. 70% bacteria resisted to penicillin, cephazolin, and streptomycin while double resistance to furazolidone/streptomycin increased to with time from 0% to 83% in PCG. In EMD, 70% bacteria resisted to streptomycin and furazolidone, and double resistance to furazolidone/streptomycin increased with time from 0% to 60%. In THOD, 50% bacteria resisted to £]-lactam drugs, 100% bacteria resisted to cephazolin, and 67% bacteria doubly resisted to ampicillin/amoxycillin, cephalexin/cephazolin, cephalexin/streptomycin and cephazolin/streptomycin. Further, the detection of tetB, tetD, tetM, tetS and tetX resistance, tetracycline resistance genes, in the chromosomal DNAs from 17 multiple resistance isolates were performed by PCR. The PCR products were confirmed by digestion of restriction enzymes. The data indicated that J39-1, J39-2, K26-4 and K27-2, strains from THOD, together with N18-5 and M35-2, from PCG, were identified as carrying tetB. From EMD, The tetB and tetM genes were detected in P19-1, P19-3, P32-1 and Q8-3, whereas strain O2-3 carried tetS gene.

Widespread tetracycline resistance (TcR) has limited the clinical use of Tc for the treatment of bacterial infections. Tet(O) protein is present in many bacteria and is the major transmissible TcR determinant in Campylobacter jejuni, a common cause of acute bacterial diarrhea worldwide. Tet(O) protects ribosomes against the inhibition of protein synthesis by Tc. Tet(O) binds to the ribosome at a similar site as EF-G, a structural homologue of Tet(O) with GTPase activity that is required for protein elongation. EF-G interfered with the kinetics of Tet(O)-mediated Tc release suggesting that EF-G competes with Tet(O) for ribosome binding. Indirect assessment of EF-G and Tet(O) binding to 70S ribosomes by GTP hydrolysis was unable to clearly demonstrate competition for binding. This thesis contributed to the further understanding of the kinetics of Tc release by Tet(O), and may facilitate the development of novel strategies to overcome Tet(O)-mediated TcR in bacteria which cause human infections.

No description available.

Thesis (Ph. D.)--University of Washington, 1998. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1998. / Includes bibliographical references.

<p> The most uncommon form of tetracycline resistance is enzymatic inactivation of the drug. The first protein characterized that was shown to have this ability was TetX, a 44-kDa cytoplasmic protein responsible for inactivating tetracycline in E. coli. The associated gene, tetX, was found on a transposon in the bacterium Bacteroides fragilis, and encodes an NADP-requiring, FAD-dependent monooxygenase. TetX modifies the structure of tetracycline by the addition of a hydroxyl to the C-11a position, altering the β-diketone system of the tetracycline that is responsible for antibiotic activity. This project was designed to search for novel tetracycline inactivators, and to determine the origin of the tetX. Initially, the search for TetX-like proteins in S. coelicolor and C. hutchinsonii was performed using homologous protein sequences found using BLAST searches. Each of the genes encoding the homologous protein sequences was cloned, over-expressed and purified, then analyzed using HPLC and LC/MS methods to determine their tetracycline inactivating ability. Next, the published tetracycline inactivators Tet34 and Tet37 were tested for their ability to inactivate the drug using HPLC and LC/MS methods, after being cloned, over-expressed and purified. Finally, a search of the Actinomycete library belonging to the Wright Laboratory was conducted looking for novel tetracycline inactivators. Bioassays were the first step in a series of experiments done, with HPLC and LC/MS assays eventually being used to determine if an inactivation event was occurring. The homologous sequences from S. coelicolor and C. hutchinsonii did not inactivate tetracycline as determined by HPLC and LC/MS data. The potential inactivators, Tet34 and Tet37, were also found to be void of tetracycline inactivating activity. Finally, one isolate in the actinomycete library was thought to be inactivating the drug, however, upon further inspection via HPLC and LC/MS methods this inactivation event was dismissed. Future research should focus on the search for novel enzymes capable of modifying the structure of tetracycline, as well as the origin of the only known tetracycline inactivator, tetX.</p> / Thesis / Master of Science (MSc)

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [67]-81).

Mycoplasma hyopneumoniae é o agente etiológico da pneumonia enzoótica, enfermidade distribuída mundialmente em rebanhos suínos nas fases de crescimento e terminação. A pneumonia enzoótica tem sido considerada uma das mais importantes causas de perdas econômicas na suinocultura mundial. Tendo em vista a disponibilidade dos genomas completos de três linhagens diferentes de M. pneumoniae, sendo duas patogênicas (linhagens 7448 e 232) e outra não patogênica (linhagem J) e a ausência de sistemas genéticos adequados para o estudo destes genomas, é necessidade emergente o desenvolvimento de ferramentas genéticas funcionais neste organismo. Atualmente, cinco espécies de micoplasmas possuem vetores replicativos disponíveis para transformação. No entanto nenhum deles possui a oriC de M. hyopneumoniae, e estudos sugerem que estes vetores são espécie-específicos e não seriam replicados em M. hyopneumoniae. Este trabalho teve como objetivos a construção de um vetor replicativo e o desenvolvimento de um sistema para transformação de M. hyopneumoniae. Os resultados alcançados constituem uma etapa prévia e imprescindível para o estudo de supostas regiões promotoras nesta espécie. O plasmídio replicativo pOSTM construído neste trabalho foi obtido a partir do vetor pUC18, adicionando-se a origem de replicação de M. hyopneumoniae e o cassete de expressão do gene de resistência à tetraciclina (tetM), controlado pelo promotor do gene da espiralina de Spiroplasma citri. A transformação foi realizada através de eletroporação e as células transformantes foram selecionadas pelo fenótipo de resistência à tetraciclina. Os transformantes resistentes à tetraciclina foram confirmados através da amplificação por PCR de porção do vetor inserido nas células. Tal comprovação permite concluir que o M. hyopneumoniae é um organismo susceptível à transformação e que o determinante tetM heterólogo é funcional neste patógeno. / Mycoplasma hyopneumoniae is the etiological agent of enzootic pneumonia of pigs.The disease has a worldwide distribution in growing and finishing pigs. The enzootic pneumonia has been considered one of the most important causes of economic losses in the worldwide swine breeding. The now available complete sequences of the genomes of two pathogenic (7448 and 232) and one non-pathogenic strain (J) of M. hyopneumoniae and the lack of suitable genetic systems to study these genomes points to the emergent need for the development of functional genetic tools for this organism. Currently, there are replicating vectors available for five species of mycoplasmas. However none of them posses oriC of M. hyopneumoniae, and studies suggest that these vectors are species-specific and they would not be functional in M. hyopneumoniae. The aim of the present study was to construct a replicating vector and the development of a system for transformation of M. hyopneumoniae. These constitute a previous and essential stage for the study of putative promoter regions in this species. To construct the replicating plasmid pOSTM the oriC of M. hyopneumoniae and the expression cassette containing the gene for tetracycline resistance (tetM), controlled by spiralin gene promoter of Spiroplasma citri, were introduced into the vector pUC18. The transformation was achieved by electroporation and transformants were selected for tetracycline resistance. Tetracycline resistance transformants were confirmed through PCR amplification of portion of the inserted vector. Such evidence allows the conclusion that M. hyopneumoniae is amenable to transformation and heterologous tetM determinant is functional in this pathogen.

Mycoplasma hyopneumoniae é o agente etiológico da pneumonia enzoótica, enfermidade distribuída mundialmente em rebanhos suínos nas fases de crescimento e terminação. A pneumonia enzoótica tem sido considerada uma das mais importantes causas de perdas econômicas na suinocultura mundial. Tendo em vista a disponibilidade dos genomas completos de três linhagens diferentes de M. pneumoniae, sendo duas patogênicas (linhagens 7448 e 232) e outra não patogênica (linhagem J) e a ausência de sistemas genéticos adequados para o estudo destes genomas, é necessidade emergente o desenvolvimento de ferramentas genéticas funcionais neste organismo. Atualmente, cinco espécies de micoplasmas possuem vetores replicativos disponíveis para transformação. No entanto nenhum deles possui a oriC de M. hyopneumoniae, e estudos sugerem que estes vetores são espécie-específicos e não seriam replicados em M. hyopneumoniae. Este trabalho teve como objetivos a construção de um vetor replicativo e o desenvolvimento de um sistema para transformação de M. hyopneumoniae. Os resultados alcançados constituem uma etapa prévia e imprescindível para o estudo de supostas regiões promotoras nesta espécie. O plasmídio replicativo pOSTM construído neste trabalho foi obtido a partir do vetor pUC18, adicionando-se a origem de replicação de M. hyopneumoniae e o cassete de expressão do gene de resistência à tetraciclina (tetM), controlado pelo promotor do gene da espiralina de Spiroplasma citri. A transformação foi realizada através de eletroporação e as células transformantes foram selecionadas pelo fenótipo de resistência à tetraciclina. Os transformantes resistentes à tetraciclina foram confirmados através da amplificação por PCR de porção do vetor inserido nas células. Tal comprovação permite concluir que o M. hyopneumoniae é um organismo susceptível à transformação e que o determinante tetM heterólogo é funcional neste patógeno. / Mycoplasma hyopneumoniae is the etiological agent of enzootic pneumonia of pigs.The disease has a worldwide distribution in growing and finishing pigs. The enzootic pneumonia has been considered one of the most important causes of economic losses in the worldwide swine breeding. The now available complete sequences of the genomes of two pathogenic (7448 and 232) and one non-pathogenic strain (J) of M. hyopneumoniae and the lack of suitable genetic systems to study these genomes points to the emergent need for the development of functional genetic tools for this organism. Currently, there are replicating vectors available for five species of mycoplasmas. However none of them posses oriC of M. hyopneumoniae, and studies suggest that these vectors are species-specific and they would not be functional in M. hyopneumoniae. The aim of the present study was to construct a replicating vector and the development of a system for transformation of M. hyopneumoniae. These constitute a previous and essential stage for the study of putative promoter regions in this species. To construct the replicating plasmid pOSTM the oriC of M. hyopneumoniae and the expression cassette containing the gene for tetracycline resistance (tetM), controlled by spiralin gene promoter of Spiroplasma citri, were introduced into the vector pUC18. The transformation was achieved by electroporation and transformants were selected for tetracycline resistance. Tetracycline resistance transformants were confirmed through PCR amplification of portion of the inserted vector. Such evidence allows the conclusion that M. hyopneumoniae is amenable to transformation and heterologous tetM determinant is functional in this pathogen.

Mycoplasma hyopneumoniae é o agente etiológico da pneumonia enzoótica, enfermidade distribuída mundialmente em rebanhos suínos nas fases de crescimento e terminação. A pneumonia enzoótica tem sido considerada uma das mais importantes causas de perdas econômicas na suinocultura mundial. Tendo em vista a disponibilidade dos genomas completos de três linhagens diferentes de M. pneumoniae, sendo duas patogênicas (linhagens 7448 e 232) e outra não patogênica (linhagem J) e a ausência de sistemas genéticos adequados para o estudo destes genomas, é necessidade emergente o desenvolvimento de ferramentas genéticas funcionais neste organismo. Atualmente, cinco espécies de micoplasmas possuem vetores replicativos disponíveis para transformação. No entanto nenhum deles possui a oriC de M. hyopneumoniae, e estudos sugerem que estes vetores são espécie-específicos e não seriam replicados em M. hyopneumoniae. Este trabalho teve como objetivos a construção de um vetor replicativo e o desenvolvimento de um sistema para transformação de M. hyopneumoniae. Os resultados alcançados constituem uma etapa prévia e imprescindível para o estudo de supostas regiões promotoras nesta espécie. O plasmídio replicativo pOSTM construído neste trabalho foi obtido a partir do vetor pUC18, adicionando-se a origem de replicação de M. hyopneumoniae e o cassete de expressão do gene de resistência à tetraciclina (tetM), controlado pelo promotor do gene da espiralina de Spiroplasma citri. A transformação foi realizada através de eletroporação e as células transformantes foram selecionadas pelo fenótipo de resistência à tetraciclina. Os transformantes resistentes à tetraciclina foram confirmados através da amplificação por PCR de porção do vetor inserido nas células. Tal comprovação permite concluir que o M. hyopneumoniae é um organismo susceptível à transformação e que o determinante tetM heterólogo é funcional neste patógeno. / Mycoplasma hyopneumoniae is the etiological agent of enzootic pneumonia of pigs.The disease has a worldwide distribution in growing and finishing pigs. The enzootic pneumonia has been considered one of the most important causes of economic losses in the worldwide swine breeding. The now available complete sequences of the genomes of two pathogenic (7448 and 232) and one non-pathogenic strain (J) of M. hyopneumoniae and the lack of suitable genetic systems to study these genomes points to the emergent need for the development of functional genetic tools for this organism. Currently, there are replicating vectors available for five species of mycoplasmas. However none of them posses oriC of M. hyopneumoniae, and studies suggest that these vectors are species-specific and they would not be functional in M. hyopneumoniae. The aim of the present study was to construct a replicating vector and the development of a system for transformation of M. hyopneumoniae. These constitute a previous and essential stage for the study of putative promoter regions in this species. To construct the replicating plasmid pOSTM the oriC of M. hyopneumoniae and the expression cassette containing the gene for tetracycline resistance (tetM), controlled by spiralin gene promoter of Spiroplasma citri, were introduced into the vector pUC18. The transformation was achieved by electroporation and transformants were selected for tetracycline resistance. Tetracycline resistance transformants were confirmed through PCR amplification of portion of the inserted vector. Such evidence allows the conclusion that M. hyopneumoniae is amenable to transformation and heterologous tetM determinant is functional in this pathogen.