Background: This study aimed to detect enolase and pyruvate kinase, key metabolic enzymes in glycolysis, in fluoride-resistant and fluoride-sensitive Streptococcus mutans strains isolated from diabetic dental caries. Enolase catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate (PEP), while pyruvate kinase converts PEP to pyruvate. Methods: This cross-sectional study involved 32 Streptococcus mutans strains isolated from dental caries in Khartoum, Sudan, between April and June 2022. The strains were identified using conventional methods, and their fluoride sensitivity was tested by culturing them in BHI agar under microaerophilic conditions with and without fluoride. The presence of enolase and pyruvate kinase was detected using conventional PCR, and the results were analyzed with SPSS software version 23.0.
Results: In this study, enolase and pyruvate kinase enzymes were detected in 32 Streptococcus mutans strains using PCR. Enolase was present in 59% of strains, while pyruvate kinase was found in 75%. The presence of pyruvate kinase was linked to fluoride resistance, with significant resistance observed at fluoride concentrations of 80, 125, and 250 ppm, showing p-values of 0.037, 0.002, and 0.009, respectively.
Conclusion: Among the isolated fluoride-resistant and fluoride-sensitive Streptococcus mutans, 53% harbored both enolase and pyruvate kinase. Only 6% carried the enolase gene, and 22% had the pyruvate kinase gene. The absence of pyruvate kinase in fluoride-resistant strains may contribute to higher fluoride resistance, with significant resistance observed at concentrations of 80, 125, and 250 ppm, where 87%, 75%, and 50% of strains resisted fluoride, respectively.