Objectives: Little is known about the effect of diet on the oral microbiota of infants, although diet is known to affect the gut microbiota. The aims of the present study were to compare the oral microbiota in breast-fed and formula-fed infants, and investigate growth inhibition of streptococci by infant-isolated lactobacilli.
Methods: A total of 207 mothers consented to participation of their 3-month-old infants. A total of 146 (70.5%) infants were exclusively and 38 (18.4%) partially breast-fed, and 23 (11.1%) were exclusively formula-fed. Saliva from all of their infants was cultured for Lactobacillus species, with isolate identifications from 21 infants. Lactobacillus isolates were tested for their ability to suppress Streptococcus mutans and S sanguinis. Oral swabs from 73 infants were analysed by the Human Oral Microbe Identification Microarray (HOMIM) and by quantitative polymerase chain reaction for Lactobacillus gasseri.
Results: Lactobacilli were cultured from 27.8% of exclusively and partially breast-fed infants, but not from formula-fed infants. The prevalence of 14 HOMIM-detected taxa, and total salivary lactobacilli counts differed by feeding method. Multivariate modelling of HOMIM-detected bacteria and possible confounders clustered samples from breast-fed infants separately from formula-fed infants. The microbiota of breast-fed infants differed based on vaginal or C-section delivery. Isolates of L plantarum, L gasseri, and L vaginalis inhibited growth of the cariogenic S mutans and the commensal S sanguinis: L plantarum >L gasseri >L vaginalis.
Conclusions: The microbiota of the mouth differs between 3-month-old breast-fed and formula-fed infants. Possible mechanisms for microbial differences observed include species suppression by lactobacilli indigenous to breast milk.
*Department of Odontology, Cariology, Umeå University
†Department of Odontology, Microbiology, Umeå University
‡Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden
§Department of Molecular Genetics, Forsyth Institute, Harvard School of Dental Medicine, Boston, MA.
Address correspondence and reprint requests to Pernilla Lif Holgerson, Department of Odontology, Umeå University, SE-901 87 Umeå, Sweden (e-mail: email@example.com).
Received 26 January, 2012
Accepted 2 August, 2012
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The study was supported by grants from Västerbotten County Council, the Swedish Patent Revenue Foundation, and by Public Health Service Grant DE-015847 (A.T.) from the National Institute of Dental and Craniofacial Research, and Henning and Johan Throne-Holst's Foundation (P.L.H.).
The authors report no conflicts of interest.