title: Mutans streptococci genetic strains in children with severe early childhood caries: follow-up study at one-year post-dental rehabilitation therapy.
abstract: BACKGROUND
  Genotypic strains of cariogenic mutans streptococci (MS) may vary in important virulence properties. In previous published studies, we identified 39 MS strains from pediatric patients undergoing full-mouth dental rehabilitation, including the removal and/or repair of carious lesions and application of antimicrobial rinse and fluoride varnish.
  
  
  OBJECTIVE
  The objectives of this current 1-year follow-up study are to assess the variability of MS strains that occur at 1-year post-rehabilitation and characterize the xylitol-resistance properties of MS strains that predominate.
  
  
  METHODS
  Plaque from five children with severe early childhood caries was collected 1-year post-rehabilitation. MS isolates were subjected to arbitrarily primed-polymerase chain reaction (AP-PCR) for identification of genetic strains and in vitro xylitol-inhibition experiments. To more precisely define strain distributions within each patient, we isolated large numbers of isolates per patient.
  
  
  RESULTS
  MS strains diminished from several strains pre-rehabilitation, to one dominant strain at 1-year post-rehabilitation, with several new emergent strains. The majority of the clinical MS strains, as well as the Streptococcus mutans laboratory strains ATCC 25175 and 35668, were predicted to undergo 50% inhibition with 2.48-5.58% xylitol, with some clinical MS strains being significantly more resistant in vitro.
  
  
  CONCLUSIONS
  Our follow-up study using patients from the original cohort demonstrates that specific MS strains are dominant at 1-year post-dental rehabilitation. Most of the clinical MS strains are similar in xylitol resistance to the attenuated S. mutans ATCC control strains, with some strains being more resistant to xylitol in vitro.
authors.affiliation: Department of Pediatric Dentistry, Oregon Health & Science University (OHSU) School of Dentistry, Portland, OR.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Palmer
authors.forename: Alex
authors.initials: A
authors.lastname: Vo
authors.forename: Shelby B
authors.initials: SB
authors.lastname: Hiles
authors.forename: Patricia
authors.initials: P
authors.lastname: Peirano
authors.forename: Samyia
authors.initials: S
authors.lastname: Chaudhry
authors.forename: Amy
authors.initials: A
authors.lastname: Trevor
authors.forename: Iraj
authors.initials: I
authors.lastname: Kasimi
authors.forename: Jill
authors.initials: J
authors.lastname: Pollard
authors.forename: Christopher
authors.initials: C
authors.lastname: Kyles
authors.forename: Michael
authors.initials: M
authors.lastname: Leo
authors.forename: Beth
authors.initials: B
authors.lastname: Wilmot
authors.forename: John
authors.initials: J
authors.lastname: Engle
authors.forename: John
authors.initials: J
authors.lastname: Peterson
authors.forename: Tom
authors.initials: T
authors.lastname: Maier
authors.forename: Curtis A
authors.initials: CA
authors.lastname: Machida