Download CP 12 Chapter 8 - Trends in Clinical Periodontology

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PART 1 Biologic Basis of Periodontology
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Figure 8-1 Various periodontal and cariogenic species grown on agar plates. A, Streptococcus mitis are gram-positive, fast-growing, facultatively anaerobic bacteria that are easy to culture on a blood-agar plate. A clear halo surrounding the colonies appears through hemolytic
activity. B, Veillonella parvula are anaerobic gram-negative small cocci. They form small transparent colonies (<1.0 mm) after 48 hours of
incubation. C, Actinomyces viscosus are microaerophilic to anaerobic gram-positive rods with possible branches (pseudomycelium). They
form slimy white spherical colonies in 48 hours. D, The typical colony morphology of Streptococcus sanguinis (right) and Actinomyces
odontolyticus (left). E, Lactobacillus spp. will typically grow on Rogosa agar as a sesame seed. F, Streptococcus gordonii are facultative,
anaerobic, gram-positive cocci. On a blood plate, colonies of 1 mm to 3 mm are formed within 48 hours. These bacteria are α-hemolytic,
which results in the formation of a clear halo surrounding the colony. G, This selective agar plate, which contains crystal violet and erythromycin (i.e., a CVE-agar plate), will allow Fusobacterium nucleatum to grow as a round, flat rhizoid, opaque purple colony. H, A detailed
picture of Porphyromonas gingivalis (green-brown colony) and Prevotella intermedia (black colony) on a classic nonspecific blood-agar plate.
I, Prevotella nigrescens forms like Prevotella intermedia, a black pigmented colony on a blood agar plate. It is a strictly anaerobic bacterium
with growth that is limited to an oxygen-free environment. J, A detailed picture of Parvimonas micra (small white colony) next to Porphyromonas gingivalis (green-brown colony) on a classic nonspecific blood-agar plate. K, A detailed picture of Aggregatibacter actinomycetemcomitans grown on a selective agar plate that contains tryptic soy, horse serum, bacitracin, and vancomycin (i.e., a TSBV-agar plate).
CHAPTER 8 Biofilm and Periodontal Microbiology
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Figure 8-1, cont’d L, It is extremely difficult to culture Treponema denticola (spirochete) on an agar plate and therefore not possible to
identify this bacteria with classic culture. A phase-contrast microscope, a dark-field microscope, or an electron microscope is often used to
visualize this bacterium. Identification and quantification is only possible through DNA analysis. M, On a selective agar plate that contains
trypticase yeast extract, cystine, sucrose, and bacitracin (i.e., a TYCSB agar plate), Streptococcus mutans will grow as a sugar cube.
N, Eubacterium nodatum colony morphology strongly depends on its substrate. Its growth is very slow, and it is an obligate anaerobic
gram-positive rod. O, Tannerella forsythia are fastidious bacteria that are therefore difficult to culture. This organism grows on a blood-agar
plate as a smooth white colony with a faded edge. The bacteria are strictly anaerobic. P, The typical colony morphology of Streptococcus
sobrinus on TYCSB agar (colony with a white halo). Q, Capnocytophaga are slowly growing bacteria that require an elevated CO2 concentration for their growth. They are facultative anaerobic rods. R, Campylobacter rectus grows on a Hammond plate as small, smooth,
opaque, round colonies with a black color. S, Eikenella corrodens has a variable colony morphology and shows different biochemical and
serologic reactions. Because of the difficult determination with classic culture, identification and quantification through DNA techniques
are very suitable for this organism. E. corrodens cells are facultative, anaerobic, gram-negative rods. (A, B, C, F, I, L, N, O, Q, and S courtesy
ADD Clinident, Malden, The Netherlands.)
The Oral Cavity From a Microbe’s
Perspective
With the exception of those microorganisms that are present in
feces and in secretory fluids, all bacteria maintain themselves
within their host by adhering to a surface. This principle also
applies to the oral cavity. From an ecologic viewpoint, the
oral cavity, which communicates with the pharynx, should be
considered as an “open growth system” with an uninterrupted
ingestion and removal of microorganisms and their nutrients. A
dynamic equilibrium exists between the adhesion forces of microorganisms and a variety of removal forces that originate from the
following sources: (1) swallowing, mastication, or blowing the
nose; (2) tongue and oral hygiene implements; (3) the wash-out
effect of the salivary, nasal, and crevicular fluid outflow; and (4)
the active motion of the cilia of the nasal and sinus walls. Most