Differentiation of Protein L-Containing and Albumin-BindingPeptostreptococcus magnusIsolates by DNA Amplification, Ribotyping, and Pulsed Field Gel Electrophoresis
Abstract Protein L (L) and albumin-binding (A) proteins may be virulence factors of Peptostreptococcus magnus isolates. When 32 P. magnus isolates from different countries were screened for protein L gene sequences by the polymerase chain reaction (PCR), the only positive isolates were three which had been previously identified. Protein L-containing (L + A − ) or albumin-binding isolates (L − A + ) and unrelated isolates (L − A − ) were analysed using three genotyping methods not previously used to distinguish strains with these putative virulence factors — PCR-restriction endonuclease analysis (REA) of 16 SrRNA, ribotyping, and macrorestriction endonuclease analysis of DNA by pulsed-field gel electrophoresis (PFGE). PFGE produced the greatest discrimination (ten banding patterns), followed by ribotyping (nine banding patterns) and PCR-REA of 16S rRNA amplicons (two banding patterns). Based on patterns from PFGE and ribotyping, cluster analysis showed that the three L + A − isolates were more closely related to each other than with other isolates. Six of eight L − A + isolates formed two indistinguishable groups of three isolates each, but these two groups were genetically distant from the other two unrelated L − A + isolates. L − A − isolates were not related, either among themselves, or to any other isolates. Thus, L + and A + phenotypes and genotyping methods (PFGE and ribotyping) are useful for differentiating P. magnus isolates and identifying specific strain types.