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Classification of oral pigmented anaerobic bacilli by pyrolysis mass spectrometry and biochemical tests
J T Magee1, J M Hindmarch, B I Duerden
1Department of Experimental and Clinical Microbiology, University of Sheffield Medical School.
Abstract:
Clinical (66) and reference (5) strains of pigmented gram-negative anaerobic bacilli, identified as Prevotella intermedia (47), Pr. melaninogenica (1), Pr. corpora (8), Porphyromonas asaccharolyticus (12), P. endodontalis (1) and P. gingivalis (2), were examined by pyrolysis mass spectrometry (PMS) and in conventional tests. Numerical classification based on conventional test reaction patterns (CTRPs) resolved five clusters, four comprising strains identified as Pr. intermedia, Pr. corpora, Pr. melaninogenica, and P. gingivalis respectively, and one comprising strains identified as P. asaccharolyticus and P. endodontalis. Numerical classification based on PMS showed a similar division, with decreasing homogeneity of chemical composition in the order Pr. intermedia, Pr. corpora, P. asaccharolyticus, which agreed with the order of homogeneity in CTRPs. PMS clusters corresponding to the genus Porphyromonas were clearly distinct from those of the genus Prevotella. PMS and CTRP classification disagreed on cluster membership for six strains. PMS identification from blind challenge sets was in agreement with conventional identification for 64 of 67 strains.
Insights
Pyrolysis mass spectrometry (PMS) effectively identified pigmented gram-negative anaerobic bacilli, closely matching conventional tests. This technique offers a reliable method for distinguishing Prevotella and Porphyromonas species.
Area of Science:
- Microbiology
- Analytical Chemistry
- Bacteriology
Background:
- Pigmented gram-negative anaerobic bacilli, including Prevotella and Porphyromonas species, are clinically significant.
- Accurate identification of these bacteria is crucial for diagnosis and treatment.
Purpose of the Study:
- To evaluate the efficacy of pyrolysis mass spectrometry (PMS) in identifying and classifying Prevotella and Porphyromonas species.
- To compare PMS-based classification with conventional phenotypic tests.
Main Methods:
- Analysis of 67 clinical and reference strains using pyrolysis mass spectrometry (PMS).
- Comparison of PMS data with conventional test reaction patterns (CTRPs).
- Numerical classification and cluster analysis for both methods.
Main Results:
- PMS and CTRPs yielded similar classifications, distinguishing Prevotella and Porphyromonas genera.
- Homogeneity of chemical composition by PMS correlated with CTRP homogeneity.
- PMS correctly identified 64 out of 67 strains in blind challenge sets.
Conclusions:
- Pyrolysis mass spectrometry (PMS) is a valuable tool for the identification and differentiation of Prevotella and Porphyromonas species.
- PMS provides a reliable and accurate alternative to conventional identification methods for these anaerobic bacilli.