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Peroxidase reaction as a parameter for discrimination of Streptococcus mutans and Streptococcus sobrinus
1Department of Operative Dentistry and Periodontology, School of Medicine, University of Leipzig, Germany.
Abstract:
425 strains of mutans streptococci and 12 reference strains were investigated by membrane fatty acid spectra (MFAS) and peroxidase reaction (PR) after aerobic and anaerobic incubation. 423 strains were identified as Streptococcus mutans. The remaining 2 strains were identified as Streptococcus sobrinus. The PR of 29 strains was doubtful; immediately after anaerobic incubation a negative PR changed into a slightly positive PR. To test the diagnostic value of PR the strains were additionally investigated by means of species-specific polymerase chain reactions (PCR). The species-specific PCRs were developed on the basis of the respective genes of 16S rRNA of the pathogens S. mutans and S. sobrinus. Specificity and sensitivity were tested on reference strains (n = 17) and negative control strains (n = 39). The results of this investigation showed that an anaerobic incubation regime could lead to false-positive (S. mutans) or false-negative (S. sobrinus) PR. The 425 MS strains were classified as either S. mutans (n = 420) or S. sobrinus (n = 5). The findings on the reference strains required a reclassification of S. mutans V 100 into S. sobrinus V 100. Summarising, it is possible now to differentiate strains of mutans streptococci by MFAS and PR after aerobic incubation.
Insights
Membrane fatty acid spectra (MFAS) and peroxidase reaction (PR) effectively differentiate mutans streptococci strains after aerobic incubation. Anaerobic conditions can yield inaccurate PR results, impacting Streptococcus mutans and Streptococcus sobrinus identification.
Area of Science:
- Microbiology
- Molecular Biology
- Clinical Diagnostics
Background:
- Mutans streptococci are key pathogens in dental caries.
- Accurate identification of Streptococcus mutans and Streptococcus sobrinus is crucial for epidemiological studies and treatment strategies.
- Current identification methods may face challenges with certain incubation conditions.
Purpose of the Study:
- To evaluate the diagnostic accuracy of membrane fatty acid spectra (MFAS) and peroxidase reaction (PR) for identifying mutans streptococci.
- To compare the reliability of MFAS and PR under aerobic versus anaerobic incubation.
- To validate species-specific polymerase chain reactions (PCR) for differentiating S. mutans and S. sobrinus.
Main Methods:
- Investigated 425 mutans streptococci strains and 12 reference strains using MFAS and PR.
- Performed aerobic and anaerobic incubation for PR analysis.
- Developed and utilized species-specific PCR assays targeting the 16S rRNA gene.
- Tested specificity and sensitivity of PCR on reference and control strains.
Main Results:
- MFAS and PR after aerobic incubation accurately differentiated S. mutans (420 strains) and S. sobrinus (5 strains).
- Anaerobic incubation led to false-positive PR for S. mutans and false-negative PR for S. sobrinus.
- PCR confirmed the classification of strains and necessitated reclassification of one reference strain.
- A total of 423 strains were identified as S. mutans and 2 as S. sobrinus initially.
Conclusions:
- MFAS combined with PR under aerobic incubation provides a reliable method for differentiating mutans streptococci.
- Anaerobic incubation should be avoided for PR-based identification to prevent misclassification.
- Species-specific PCR serves as a valuable tool for confirming the identification of S. mutans and S. sobrinus.