| 0150 A General PTS Sugar Transport Mutant of Streptococcus mutans Fails to Colonize and Induce Caries in Rats | ||
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J.M. TANZER, University of Connecticut Health Center, Farmington, USA, L. GRANT, Univ. Connecticut, Farmington, USA, A. THOMPSON, Univ Connecticut Health Center, Farmington, USA, and D.G. CVITKOVITCH, University of Toronto, Canada
Objective: Multiple mechanisms of carbohydrate transport by S. mutans confound the analysis of their individual roles in virulence (cariogenicity). A ptsI mutant of WT strain BM71, termed DC10, is defective in the general PTS enzyme I (EI) and cannot transport any sugar via the PTS. We sought to characterize its virulence. Methods: We compared growth rates of BM71 and DC10 after adaptation to FMC defined medium and appropriate sugars, their abilities to colonize SPFOM rats, and the associated caries scores. Three groups of weanling SPFOM rats, free of indigenous mutans streptococci were provided a 56% sucrose diet and demineralized water, ad libitum, and were inoculated one day later with either 3.7 x 109 log phase CFU of DC10 or 3.7 x 108 log phase CFU of BM71. One group remained uninoculated. Recoveries of inoculants were quantified during the experiment and after euthanasia, and caries lesions scored blindly. Results: The DC10 was able to grow in defined medium supplemented with high concentration sucrose or glucose, albeit more slowly than BM71; they grew with virtually the same yield. Those of DC10 were unaffected by the presence/absence of erythromycin. This ptsI knockout apparently failed to colonize and persist in the rats as no emR-mutans streptococci could be recovered 2 weeks post-inoculation or at time of euthanasia; its wild type could be abundantly recovered at both times. The BM71-inoculated group had high caries scores, while the DC10-inoculated group had low scores that were not different from those of the uninoculated rats with their indigenous mutans-free flora. Conclusion: ptsI is a virulence determinant of S. mutans. Presumably, even when inoculated at 10-fold higher levels than its progenitor, it fails to colonize and persist on the teeth due to its defective general PTS EI. Supported by grants from Church & Dwight and MRC Canada (MT-3546). | ||
| Seq #29 - Gram-positive Cocci I 9:00 AM-11:00 AM, Thursday, 13 March 2003 Henry B. Gonzalez Convention Center Room 214C | ||
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