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Background: Lactobacillus species can contribute positively to general and oral health and are frequently acquired by breastfeeding in infancy. The present study aimed to identify oral lactobacilli in breast and formula-fed 4 month-old infants and to evaluate potential probiotic properties of the dominant Lactobacillus species detected. Saliva and oral swab samples were collected from 133 infants who were enrolled in a longitudinal study (n=240) examining the effect of a new infant formula on child growth and development. Saliva was cultured and Lactobacillus isolates were identified from 16S rRNA gene sequences. Five L. gasseri isolates that differed in 16S rRNA sequence were tested for their ability to inhibit growth of selected oral bacteria and for adhesion to oral tissues. Oral swab samples were analyzed by qPCR for Lactobacillus gasseri. Results: 43 (32.3%) infants were breastfed and 90 (67.7%) were formula-fed with either a standard formula (43 out of 90) or formula supplemented with a milk fat globule membrane (MFGM) fraction (47 out of 90). Lactobacilli were cultured from saliva of 34.1% breastfed infants, but only in 4.7% of the standard and 9.3% of the MFGM supplemented formula-fed infants. L. gasseri was the most prevalent (88% of Lactobacillus positive infants) of six Lactobacillus species detected. L. gasseri isolates inhibited Streptococcus mutans binding to saliva-coated hydroxyapatite, and inhibited growth of S. mutans, Streptococcus sobrinus, Actinomyces naeslundii, Actinomyces oris, Candida albicans and Fusobacterium nucleatum in a concentration dependent fashion. L. gasseri isolates bound to parotid and submandibular saliva, salivary gp340 and MUC7, and purified MFGM, and adhered to epithelial cells. L. gasseri was detected by qPCR in 29.7% of the oral swabs. Breastfed infants had significantly higher mean DNA levels of L. gasseri (2.14 pg/uL) than infants fed the standard (0.363 pg/uL) or MFGM (0.697 pg/uL) formula. Conclusions: Lactobacilli col

This study assessed whether the persistence of Lactobacillus reuteri DSM 17938 and ATCC PTA 5289 in saliva could delay the regrowth of mutans streptococci (MS) after a full-mouth disinfection with chlorhexidine (CHX). A randomised, double-blind, placebo-controlled study with a 6-week intervention period and 3- and 6-month follow-up was performed. 62 healthy subjects with moderate to high counts of MS were randomly assigned to a test group (n = 32) or a placebo group (n = 30). Before onset of the intervention, subjects received two sessions of professional cleaning, flossing, and application of CHX varnish and rinsed their mouth with a CHX solution between the sessions (2 days). Thereafter, the test group used probiotic lozenges (2/day) containing L. reuteri (DSM 17938 and ATCC PTA 5289; 1 × 108 CFU of each strain), and the placebo group used identical lozenges lacking the lactobacilli. Saliva samples were collected and cultured onto selective media, and isolates of L. reuteri as well as DNA directly extracted from saliva were tested by polymerase chain reaction (PCR) with specific primers. Presence of salivary MS was analysed with a chair-side test. L. reuteri was frequently detected by culture during the intervention period but in only 3 test group subjects at follow-ups. Regrowth of MS statistically significantly differed depending on the presence or absence of L. reuteri DSM 17938 detected by PCR. We conclude that cultivable L. reuteri strains may only sporadically be confirmed after termination of the intervention, but subjects with PCR-detected L. reuteridemonstrated slower regrowth of MS.