Infants’ oral microbiota differs according to feeding method

By Sarah Guy, medwireNews Reporter

The oral microbiota of 3-month old infants is distinguishable by whether they are breast- or formula-fed, show study findings.

Lactobacilli were successfully cultured from almost a third of exclusively and partially breastfed infants, while none were cultured from their formula-fed counterparts, report the researchers.

Indeed, isolates of various of these lactobacilli inhibited the growth of known dental-caries-causing oral streptococci, writes the team in the Journal of Pediatric Gastroenterology and Nutrition.

"The finding that the oral microbiota differs between breastfed and formula-fed infants, with a potentially more health-associated oral flora in breastfed infants indicates the value of prospective longitudinal studies where health outcomes, primarily early childhood caries but possibly also gut microflora and associated health conditions, are evaluated," suggest Pernilla Holgerson (Umeå University, Sweden), and co-workers.

The team took saliva samples from 207 3-month-old infants, of whom 70.5% were exclusively breastfed, 18.4% were partially breastfed, and 11.1% were exclusively formula-fed.

Overall, viable Lactobacillus species were detected in saliva from 32.4% and 27.0% of fully and partially breastfed infants, respectively, while none were detected in formula-fed infants, report the researchers.

L. gasseri was the most prevalent (87.5%) of isolates, and was detected in 25.3% of all oral swabs taken, and L. plantarum and L. vaginalis were also observed.

Holgerson and colleagues tested an isolate of each of these species from one randomly selected infant for its ability to inhibit growth of Streptococcus mutans and S. sanguinis, using a 0-2 scale where 0 denotes no visible colonies and 2 denotes no growth inhibition.

All three isolates inhibited growth of the caries-causing bacteria. L. plantarum showed the strongest growth inhibition, with a score of 0 for S. mutans and S. sanguinis at all concentrations, followed by L. gasseri and then L. vaginalis, which had dose-dependent effects

"Breast milk provides nutrition for the infant and is a source of lactobacilli, bifidobacteria and streptococci," say the authors; therefore, it is likely to affect the "establishment of the microbiota in the mouth as well as in the gut."

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