Anaerobiosis in oral cavity
Lecter-15
Dr.Baha,H. Al-Amiedi
Ph.D.Microbiolgy
Anaerobiosis in oral cavity
There have been many attempt to identify the mechanism that allow clostridia &other
Anaerobic to colonize in oral cavity
1-It is known that the oxidation-reduction potential oforal cavity is suitable for species of clostridia,such as :
1-clostridium perfringens.
2-clostridium histilyticum
2-Free-flowing saliva has high positive redox potential which shifts towered the
Negative side with the elapse of time.
3-salive is stagnant area, such as the periodental pocket and dental interproximal space where oxygen uptake may be retarded,has redox potential enough to prompte anaerobic growth
.
4-other factors that may be acting to promote suitable growth conditions in saliva for oral anaerobes include the the lack of peroxidase in saliva,the presence of salivary catalase and the depletion of oxygen by the aerobic flora,
Clostridium
Clostridiun are gram positive,obligate anaerobic,the endo spore are wider than bacilli bodies may be of central or terminal
In position &spherical or oval in shape
Clostridium are widely distributed in soil and in the intestinal tract of human &other animals it is responsible for disease:
1-tetanus
2-gas gangrene
3-botulism
4-psedomembranoud colitis
Clostridium tetani
Anaerobic gram-positive, spore-forming bacteria characteristic drumstick appearance because the terminal spore.
Spores found in soil, animal feces; may persist for months to years
Multiple toxins produced with growth of bacteria
Tetanospasmin estimated human lethal dose = 2.5 ng/kg
Transmission
Spores of clostridium tetani are commonly
Found in soil&intestinal tract of human&
Animals infection associated with:
1-puncture wounds.
2-contaminated injuries
3-sever burns
4-Non-sterile surgary,
Tetanus Pathogenesis
Anaerobic conditions allow germination of spores and production of toxins
Toxin binds in central nervous system
Interferes with neurotransmitter release to block inhibitor impulses
Leads to unopposed muscle contraction and spasm
Tetanus Complications
1-Laryngospasm
2-Fractures
3-Hypertension
4-Nosocomial infections
5-Pulmonary embolism
6-Aspiration pneumonia
7-Death
Neonatal Tetanus
Generalized tetanus in newborn infant
Infant born without protective passive immunity
Estimated >215,000 deaths worldwide in 1998
Laboratory diagnosis
1-smear from wound material show gram positive bacilli with dram stick appearance.
2-cultur is more dependable by use in cooked meat &lactose egg yolk medium
On blood agar produce hemolysin(tetanolysin)