Assessment of clonality and serotypes of Streptococcus mutans among children by multilocus sequence typing

Abstract

Studies using multilocus sequence typing (MLST) have demonstrated that Streptococcus mutans isolates are genetically diverse. Our laboratory previously demonstrated clonality of S. mutans using MLST but could not discount the possibility of sampling bias. In this study, the clonality of randomly selected S. mutans plaque isolates from African American children was examined using MLST. Serotype and presence of collagen-binding proteins (CBP) cnm/cbm were also assessed. One hundred S. mutans isolates were randomly selected for MLST analysis. Sequence analysis was performed and phylogenetic trees were generated using START2 and MEGA. Thirty-four sequence types (ST) were identified of which 27 were unique to this population. Seventy-five percent of the isolates clustered into 16 clonal groups. Serotypes observed were c (n=84), e (n=3), and k (n=11). The prevalence of S. mutans isolates serotype k was notably high at 17.5%. All isolates were cnm/cbm negative. The clonality of S. mutans demonstrated in this study illustrates the importance of localized populations studies and are consistent with transmission. The prevalence of serotype k, a recently proposed systemic pathogen, observed in this study is higher than reported in most populations and is the first report of S. mutans serotype k in a US population.

Genetic Diversity and Evidence for Transmission of Streptococcus mutans by DiversiLab rep-PCR

“…This finding indicates that these strains have identical housekeeping genes but differ within the repetitive extragenic elements. This finding offers more support of the recent report that rep-PCR can be more discriminative than MLST in some cases when evaluating S. mutans (Momeni, Whiddon, Cheon, Moser and Childers, 2015). It should also be noted that one of the previous library genotypes (L16) was reassigned to L23 due to similarities in rep-PCR profiles.…”

“…Genotypes were determined using a three minor or 1 major band difference guideline. Percent similarity was not used for determining genotypes as percent similarity becomes increasing unreliable when larger numbers of isolates are analyzed (Momeni et al, 2015). Major and minor bands were differentiated using a cut-off of 100 fluorescence units.…”

Streptococcus mutans serotypes and collagen‐binding proteins Cnm/Cbm in children with caries analysed by PCR

“…Serotype k is typically reported as representing less than 5% of S mutans isolates . Our laboratory previously reported the first detection of serotype k in a United States population at a notably high prevalence of 17.5% from a random selection of S mutans isolates . These findings suggested that the prevalence of serotype k in this population would be higher if biofilms (ie plaque) and saliva were evaluated instead of individual isolates.…”

Transmission patterns of Streptococcus mutans demonstrated by a combined rep-PCR and MLST approach

“…Three sequence types were shared among multiple individuals within different families. ST119 (Thailand), ST132 (Thailand), and ST92 (Japan) were isolates matching strains identified in published studies from other countries, while all other isolates were unique to the Uniontown population (United States) [11,39,16,40,17].…”