The diagnostic and epidemiological use of express-PCR and ribotyping in typhoid fever and salmonella infections
1998
Satorov, S. (Tajdik State Medical Univ., Dushanbe (Tadjikistan)) | Suvorov, A.N. (Institute of Experimental Medicine, St. Petersburg, (Russian Federation)) | Tez, V.Y.
Epidemically-related and non-related Salmonella strains of different serotypes were studied employing ribotyping and modified express-Polymerase Chain Reaction (express-PCR). The modified method of express-PCR (Suvorov et al., 1995) allowed us to carry out the analysis without the preliminary separation of the bacteria chromosome DNA. For ribotyping Salmonella chromosome DNA was hydrolysed with restriction enzymes (EcoRI and PstI) and separated by gel electrophoresis. DNA encoding 23S ribosomal RNA of E. coli was used as a probe for analysis. As a result of PCR for salmonella chromosome DNATs it was determined that the DNA primers do not induce DNA amplification of S. paratyphi B and S. infantis and at the same time amplify the DNA of S. typhi and S. paratyphi A strains. Amplification of the latter in turn was characterized by strict individual specificity, and permitted us to distinguish these species without a preliminary serodiagnosis. After ribotyping, the hybridizing DNA fragments containing loci for genes encoding the ribosomal RNA synthesis were determined. By comparing electrophoregrams for S. typhi DNA of the streptomycin and tetracycline-resistant strains belonging to the same phagetype and biovariant, we found two kinds of hybridizing fragments. However, the DNAs of the tetracycline-resistant epidemically non-related strains gave hybridizing fragments with sizes which were different both from each other and from conforming fragments of the streptomycin-resistant specimens
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