CLASSIFICATION OF BLACK-PIGMENTED ANAEROBES BY PYROLYSIS MASS-SPECTROMETRY (PMS) AND CONVENTIONAL TESTS (CTS)

Clinical (66: dental 53; vaginal 4; wound 9) and reference (5) strain s of pigmented Gram-negative anaerobic bacilli were examined in pyroly sis mass spectrometry (PMS) and conventional tests (CTs). The strains were identified in CTs as: Prevotella intermedia (48); Pr. melaninoge nica (1); Pr. corporis (7); Porphyromonas asaccharolytica (12); P. en dodontalis (1) and P. gingivalis (2*). Numerical classification based on CTs resolved five clusters comprising strains identified as (I) Pr . corporis, (II) Pr. melaninogenica, (III) Pr. intermedia, (IV) P. gin givalis and (V) P. asaccharolytica and P. endodontalis. Numerical clas sification based on PMS showed a similar division, with decreasing hom ogeneity in the order Pr. intermedia, Pr. corporis, P. asaccharolytica , in agreement with the ordering of homogeneity for these species in C Ts. PMS clusters corresponding the Porphyromonas spp. were clearly dis tinct from those of Prevotella spp. PMS and CT classifications disagre ed on cluster membership for only six of the strains. PMS identificati on from blind challenge sets agreed with conventional identification f or 64 of 67 strains.