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Children acquire tooth decay bacteria from multiple sources

BOSTON — Children acquire Streptococcus mutans, a bacterium that can cause tooth decay, from sources outside their families and within their families other than their mothers, according to data presented at ASM Microbe 2016.

“While the prevailing theory on S. mutans transmission suggests mother-to-child transmission as the primary route of infection, in this study 40% of children shared no strains with their mothers,” Stephanie S. Momeni, MS, MBA, a doctoral candidate in the biology department at the University of Alabama at Birmingham, said in a press release. “Of the children that did not share strains with any household members, 33% were found to have only one isolate, indicating these strains to be rare or transient.”

Stephanie S. Momeni

To determine the extra- and intrafamilial sources of dental bacteria among children, Momeni and colleagues studied S. mutans isolates (n = 13,145) from 119 African-American children and 414 of their household members. Repetitive extragenic palindromic PCR was used to compare S. mutans strains of children to their household members. The researchers noted whether PCR identified a match, and, if not, labeled the S. mutans source as extrafamilial. Strains were further analyzed to determine and catalog their genotypes.

The investigators found that 72% of children had at least one S. mutans strain that did not match any household members. Further, 28% of children shared all genotypes with members of their household, while 24% shared no genotype with any household members. Momeni and colleagues said this data is significant because it suggests that about one-third of children carry S. mutans that may not be clinically relevant and can complicate identification of strains related to disease.

Momeni and colleagues also found that genotypes matched mothers in 54% of cases, while 46% matched siblings, and 23% matched cousins. Although mothers are still considered the primary source of genotypes, the investigators said, data indicate horizontal transmission among children.

“While the data support that S. mutans is often acquired through mother-to-child interactions, the current study illuminates the importance of child-to-child acquisition of S. mutans strains and the need to consider these routes of transmission in dental caries risk assessments, prevention and treatment strategies,” Momeni said. – by David Costill 

Reference:
Momeni SS, et al. Abstract Friday-349. Presented at: ASM Microbe; June 16-20, 2016; Boston.

Disclosure: The researchers report no relevant financial disclosures.