RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS OF PCR-AMPLIFIED 16S RIBOSOMAL DNA OF HUMAN CAPNOCYTOPHAGA

The confusion in the taxonomic status of the genus Capnocytophaga has made identification of strains and studies on the role of this genus i n infectious diseases equivocal. In this study 33 strains of Capnocyto phaga including reference strains and various clinical isolates, were studied using RFLP analysis of 16S ribosomal RNA genes. The 16S riboso mal RNA (rRNA) gene sequences from whole cell suspensions and isolated genomic DNA samples were amplified by the polymerase chain reaction ( PCR) using eubacterial specific primers. PCR products were purified an d characterized by single digestions with 12 restriction endonucleases . Five of these, BanI, CfoI, HaeIII, HphI and RsaII were found to disc riminate reproducibly between strains, and restriction patterns (ribot ypes) produced by these were analysed to clarify the classification of Capnocytophaga strains. Dendrograms inferring similarities were deriv ed from these data by the UPGMA method. This analysis produced three m ajor clusters of strains, each of which was associated with a previous ly proposed species type strain: C. gingivalis, C. sputigena and C. oc hracea. The results support the division of Capnocytophaga into three species and demonstrate that, despite the heterogeneity of this genus, the modified ribotyping method provides a simple, rapid and reproduci ble way to identify Capnocytophaga strains,