Objective To establish and compare the pulsed-field gel electrophoresis （PFGE）, multiple-locus variable number tandem repeat analysis （MLVA） and automated ribotyping for subtyping of Citrobacter strains. Methods P...Objective To establish and compare the pulsed-field gel electrophoresis （PFGE）, multiple-locus variable number tandem repeat analysis （MLVA） and automated ribotyping for subtyping of Citrobacter strains. Methods PFGE protocol was optimized in terms of plug preparation procedure, restriction enzymes and configuration of electrophoretic parameters. MLVA method was evaluated by finding variable number tandem repeats in two genomes of Citrobacter strains. The ribotyping was performed by using the automated RiboPrinter system. Results We optimized the plug preparation procedure, focused on the cell suspension concentration （turbidity of 2.5 to 3.5）, SDS addition （no SDS needed） and lysis time （1 h）, and selected the appropriate restriction enzyme （Xbal） and the electrophoretic parameters （1.0 s-20.0 s for 19 h） of PFGE. There was nearly no discriminatory power of MLVA between Citrobacter strains. For 51 Citrobacter strains, automated ribotyping gave a D-value of 0.9945, while PFGE gave a D-value of 0.9969. Both PFGE and automated ribotyping clustered strains from the same sources （with the same species from the same place at the same time identified as the same source） and divided strains from different sources （from different years, places and hosts） into different subtypes. Conclusion PFGE protocol established in this paper and automated ribotyping are suitable for application in Citrobacter subtyping.展开更多
基金supported by the project (grant 2005CB522904 and 2005CB522905) from the Ministry of Scientific Technologythe project (grant 2008ZX10004-001, 2008ZX10004-008, and 2009ZX10004-101) from the Ministry of Scientific Technology and the Ministry of Health of the People’s Republic of China
文摘Objective To establish and compare the pulsed-field gel electrophoresis （PFGE）, multiple-locus variable number tandem repeat analysis （MLVA） and automated ribotyping for subtyping of Citrobacter strains. Methods PFGE protocol was optimized in terms of plug preparation procedure, restriction enzymes and configuration of electrophoretic parameters. MLVA method was evaluated by finding variable number tandem repeats in two genomes of Citrobacter strains. The ribotyping was performed by using the automated RiboPrinter system. Results We optimized the plug preparation procedure, focused on the cell suspension concentration （turbidity of 2.5 to 3.5）, SDS addition （no SDS needed） and lysis time （1 h）, and selected the appropriate restriction enzyme （Xbal） and the electrophoretic parameters （1.0 s-20.0 s for 19 h） of PFGE. There was nearly no discriminatory power of MLVA between Citrobacter strains. For 51 Citrobacter strains, automated ribotyping gave a D-value of 0.9945, while PFGE gave a D-value of 0.9969. Both PFGE and automated ribotyping clustered strains from the same sources （with the same species from the same place at the same time identified as the same source） and divided strains from different sources （from different years, places and hosts） into different subtypes. Conclusion PFGE protocol established in this paper and automated ribotyping are suitable for application in Citrobacter subtyping.
