anaerobic bacilli in oral cavity

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 of medium in which the anaerobic
• Are contained is of critical importance,the species of clostridia,such as :
• 1-clostridium perfringens.
• 2-clostridium histilyticum
• Have different negative redox requirement
• These are lower than those suitable for aerobes
• 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 low enough to promote 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
• Clostridium 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
(ANAROBES)
• Anaerobic
• Sporing
• Gram positive
• Diameter of the spore is larger than the cell resemble a spindle
• Clostridium is derived from Kloster meaning spindle
CLASSIFICATION BASED ON THE TYPE OF DISEASE PRODUCED
• A . Tetanus Cl. tetani - Present in soil
• B. Gas gangrene
– Established Cl. perfringens ‘gut’ organism
Cl. septicum
Cl. novyi
- Less pathogenic Cl. histolyticum
Cl. fallax
- Doubtful Cl. bifermentans
Cl. sporogenes
• c. Food poisoning
1. Gastroenterritis - Cl perfringens Type A


2. Botulism - Cl. botulinum/ Soil

3- big –bel Cl.perfringens type c

• D. Acute colitis - Cl. difficile / gut’ organism
(pseudomembranous colitis)

– Commonest cause of ‘nosocomial’ diarrhoea

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
• Laryngospasm
• Fractures
• Hypertension
• Nosocomial infections
• Pulmonary embolism
• Aspiration pneumonia
• 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)