Proportional Distribution and Relative Adherence of Streptococcus miteor ( mitis ) on Various Surfaces in the Human Oral Cavity

Abstract

A group of streptococci possessing the characteristics of Streptococcus miteor (S. mitis) was found to predominate on nonkeratinized human oral mucosa. These organisms averaged from 76 to 89%C of the total flora cultivable on anaerobically incubated blood agar plates from cheek, lip, and ventral tongue surfaces. They averaged 34, 40, and 18%tof the streptococci in dental plaque, in saliva, and on the tongue dorsum, respectively. Their ability to adhere to oral surfaces was studied by introducing mixtures of streptomycin-resistant strains of S. miteor, S. salivarius, and S. mutans into the mouths of volunteers. Samples of oral surfaces taken 1 hr later indicated S. miteor adhered far better than the other streptococci to buccal mucosa and to teeth, but S. salivarius showed a higher affinity to the tongue dorsum. Glucose-grown cells of S. mutans adhered feebly to all oral surfaces studied and wele rapidly cleared from the mouth. Cells of S. miteor and S. salivarius present naturally in saliva adhered to cleaned teeth comparable to in vitro cultivated strains. Electron microscopy of cells of S. miteor attached to buccal epithelial cells obtained from germfree rats indicated that the organisms possessed a fibrillar "fuzzy" coat which appeared to mediate their attachment to the epithelial cell membrane. This "fuzzy" coat was removed by treatment with trypsin, and it appears to be similar to that previously observed on cells of S. pyogenes and S. salivarius.

On the Formation of Dental Plaques

“…However, several recent studies have shown that this is not true. 116,117,77,76,118 Differences in bacterial composition between "mature" plaque and saliva have been recognized for many years, 66,37 but these were considered to be due to differences in growth rates between the various bacterial species after they arrived on the tooth surface. For example, S.salivarius, which is present in high proportions on the tongue and in saliva, but only in low proportions on teeth ( Table 1), was presumed to grow only slowly or not at all on the tooth surface.…”

“…For example, certain bacterial species have been found to adsorb to human enamel powder or teeth in vivo to a greater extent than others. 50,116,117,77,76,118 If the enamel powder is exposed to saliva in vitro to form a film of selectively adsorbed salivary constituents mimicking the natural enamel pellicle, the adsorption of some bacterial species is enhanced while that of other organisms is either unaffected or reduced. This adsorbed salivary layer has been found to increase the adsorption of strains of S.sanguis and S.mitis whereas the adsorption of S.salivarius or S.mutans tends to be unaffected or reduced.…”

“…When the bacterial populations of teeth are reduced to negligible levels by thorough cleaning and then exposed to the normal oral environment for short periods, significant numbers of organisms will become adsorbed. 100,116,117,77,76,118 After 1 hr, up to 10 6 viable bacteria can be recovered per sq cm of tooth surface. 116 It may be calculated that in such instances the bacteria occupy about 1 % of the tooth surface area available for adsorption.…”

Bacteria in the Human Mouth

“…Studies by electronmicroscopy of oral streptococci which adhere to buccal epithelial cells in rats has revealed fuzzy coats on the bacteria (Liljemark & Gibbons 1972). These coats are removed by trypsin.…”

Use of an innovative and non-invasive device for virologic sampling of cough aerosols in patients with community and hospital acquired pneumonia: a pilot study

“…PneumoniaCheck TM (ARC Medical Inc.) is a new device designed to collect specimens from the lower respiratory tract exhaled with coughs; in particular, it retains aerosol particles in a dedicated filter, preventing contamination from the upper respiratory tract (figure 1). The filter is then analysed through molecular and microbiological tests, in order to detect the presence of different pathogens [27]. Fluid mechanics principles allow the filter to separate aerosol particles from the lungs and the air coming from the upper respiratory tract.…”