This study shows for the first time that the primary gut flora in infants born by cesarean delivery may be disturbed for up to 6 months after the birth. The clinical relevance of these changes is unknown, and even longer follow-up is needed to establish how long-lasting these alterations of the primary gut flora can be.

— Oral health, the amount of salivary Streptococcus mutans and lactobacilli, and the flow rate, pH and buffer capacity of paraffin‐stimulated whole saliva were analyzed in 35 adult diabetic patients and their age‐ and sex‐matched non‐diabetic, clinically healthy controls. All patients had insulin‐dependent diabetes (IDDM) with a mean (± SD) duration of 14.0 ± 9.1 yr. The prevalence of dental caries was as high in the diabetic group as in the controls but the past caries experience was remarkably lower in those individuals whose diabetes had started at a very early age (= 7 yr). In agreement with the clinical data, the salivary levels of cariogenic microorganisms were of the same order of magnitude in both study groups. However, the relative proportion of S. mutans from the total cultivable aerobic microflora was significantly higher (P<0.01) in diabetics compared to the controls. The other studied salivary parameters did not differ between the groups. Remarkable individual differences were observed in the correlation between glucose levels of blood and whole saliva among diabetics. In spite of the noncariogenic dietary habits, the adult diabetic patients seem to be at least as susceptible to dental caries as non‐diabetics, probably due to the leakage of glucose from blood into the oral cavity.

Immunoglobulin A (IgA) and IgG antibodies against Streptococcus mutans KlR and 10449 were measured in serum and in stimulated whole saliva from two groups of naval recruits, representing high or low caries susceptibility. The antibody assays were performed by using the enzyme-linked immunosorbent assay, and the results were expressed by a method able to estimate the amount of high-avidity and total specific antibodies. As a control, concentrations of salivary total immunoglobulins were related to the amounts of specific antibodies. Further, antibodies were assayed against three antigens, unrelated to the streptococci. No clear differences were observed in serum antibodies between the subjects with high or low caries susceptibility. However, in saliva, low caries susceptibility was associated with a high amount of total antigen-specific IgA, and possibly IgG, against S. mutans. This difference between the groups still existed when the amounts of specific antibodies were related to the amounts of salivary immunoglobulins. There were no differences in the amounts of total specific antibodies against the unrelated antigens. No differences were observed in the estimates of high-avidity anti-S. mutans antibodies between the groups, either in serum or saliva. Thus, within the limitations of the assays and crude antigen, lack of high-avidity antibodies is not responsible for caries susceptibility. Instead, the amount of anti-S. mutans antibodies seems to be linked with caries protection. The results of the present study indicate that salivary antibodies are linked with the control of human dental caries.

Gas-liquid chromatography of cellular fatty acids was used in automatic identification of clinical bacterial isolates. The intraspecies variation in the occurrence of fatty acids and the variation in the relative gas-liquid chromatography peak areas of different fatty acids were evaluated and compared with the relative peak areas of these acids. A new chromatogram comparison method involving the use of an exponential function was developed to adjust to data variation optimally. This method was compared with several previously published methods of correlation analysis with data from representative clinical bacteriological isolates. The efficacies of the methods in separating different bacterial species into distinct clusters were compared. The new exponential function method was superior to the others both in its ability to separate species into different clusters and in giving a greater degree of identity to strains within a proper cluster. The results indicate that the gas-liquid chromatography of bacterial cellular fatty acids can be used effectively in the identification of clinically isolated bacteria. However, the usefulness of the analysis depends on the comparison method used and on its ability to cope with data variations.

Twenty-eight children, aged 0.8–3.8 years, were studied with respect to the presence of mutans streptococci (MS) in dental plaque and the amount and avidity of specific serum IgG and IgM antibodies against whole cells and streptococcal protein antigen I/II (SA I/II) of Streptococcus mutans. The presence or absence of MS in dental plaque at the median age of 1.9 years predicted the caries development during a 2.7-year follow-up period with a sensitivity and specificity of 73 and 92%, respectively. The caries predictive value of a positive finding of MS at this age was as high as 92%. Almost all children had detectable amounts of serum IgG and IgM antibodies against whole cells and SA I/II of S. mutans, irrespective of the presence of detectable levels of this bacterium in dental plaque. These antibodies increased with age. The antibody levels did not differ significantly between children who were MS-negative or MS-positive. However, in MS-free children as well as in the whole study group, total specific and high-avidity antibodies of IgG class against whole cells correlated positively with antibodies against SA I/II. In MS-infected children such an association was observed for IgM but not for IgG antibodies. This different serum antibody profile in MS-negative and -positive children may be related to the mode of immunization with S. mutans.