IADR Abstract Archives

Selection of Mutans Streptococci Strains Following Caries Preventive Therapy

Objectives: Dental caries are induced by microorganisms in the oral cavity, and represents one of the major health concerns in children. Mutans streptococci (MS) are major microbiological determinants of dental caries. The objectives of this study are to genetically define and assess the cariogenic potential of MS isolates that emerge following caries preventive therapy in children.

Methods: Using arbitrarily-primed polymerase chain reaction (AP-PCR), MS genotypes were developed from nine pediatric patients undergoing caries preventive therapy, including restoration, antimicrobial rinse and fluoride varnish. Plaque was collected pre- and post-treatment (2-4 weeks), and MS strains were isolated by bacitracin selection, subjected to AP-PCR for assignment within genotypic groups, and characterized for acidogenesis and acid tolerance.

Results: Inter-patient variability in genotypes was high, but with selected patients, intra-patient variability was low between the pre- and post-treatment collections, with some genotypes undergoing significant shifts in number. One genotype (GB) in patient G increased from 14% to 78% of the population following treatment, and was highly acidogenic, yielding a pH of 4.368 (n=39; SE=0.017) after 3 days of growth in phenol red dextrose. Control S. mutans strains UA159, ATCC 25175 and ATCC 35668 generated pH values of 4.67-4.89 (n=4; SE<0.07). Another genotype (KD) in patient K increased from 2% to 24% of the population following treatment, and was highly acid-tolerant, with an acid tolerance (AT) index of 0.858 (n=14; SE=0.124). The AT index is defined by bacterial numbers surviving treatment at pH 2.8 divided by bacterial numbers surviving at pH 7.0.

Conclusions: Caries preventive therapy resulted in population increases of highly acidogenic or acid-tolerant MS strains. The implications are that caries preventive therapy may not always eliminate MS strains with high cariogenic potential, and that well-accepted practices for caries prevention should be more closely examined for efficacy.

Supported by OCTRI and OHSU School of Dentistry.


AADR/CADR Annual Meeting
2010 AADR/CADR Annual Meeting (Washington, D.C.)
Washington, D.C.
2010
1420
Microbiology / Immunology and Infection Control
  • Palmer, Elizabeth  ( Oregon Health & Science University, Portland, OR, USA )
  • Peterson, John  ( Oregon Health & Science University, Portland, OR, USA )
  • Maier, Tom  ( Oregon Health & Science University, Portland, OR, USA )
  • Machida, Curtis  ( Oregon Health & Science University, Portland, OR, USA )
  • Finlayson, Tyler  ( Oregon Health & Science University, Portland, OR, USA )
  • Nielsen, Truman  ( Oregon Health & Science University, Portland, OR, USA )
  • Peirano, Patricia  ( Oregon Health & Science University, Portland, OR, USA )
  • Nguyen, Aivan  ( Oregon Health & Science University, Portland, OR, USA )
  • Vo, Alex  ( Oregon Health & Science University, Portland, OR, USA )
  • Jackson, Stephen  ( Oregon Health & Science University, Portland, OR, USA )
  • Edwards, Issac  ( Oregon Health & Science University, Portland, OR, USA )
  • Marsh, Katie  ( Oregon Health & Science University, Portland, OR, USA )
    • Poster Session
    Streptococci
    03/06/2010