Anaerobic Bacteria part II

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Anaerobic Bacteriapart II

• Praphan Luangsook

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Conclusion

• Terms anaerobe, facultative anaerobe, obligate
  anaerobe etc
• Toxic of oxygen and defense mechanism from
  bacteria

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• Some anaerobes produce Superoxide Dismutase
• Levels correlate with O2 Sensitivity
• Allow survival outside of usual niche ? Cause
  Disease

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• Redox potential
• Anaerobes as Normal flora
• Anaerobic infection
• Characteristic mechanism
• Clues
• Specimen collection
• Culture and identification

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Classification

• - Anaerobic GPC- Anaerobic GNB
• - Anaerobic GPB, non-sporeforming- Anaerobic
  GPB, sporeforming

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Sporeforming, gram positive bacilli

• Genus Clostridium
• all species form endospores
• most Clostridium hemolysis RBC
• active form secrete exotoxins as
  tetanus, botulism and gas gangrene

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Clostridium perfringens

• produces a huge array of invasins and exotoxins
• causes wound and surgical infections that lead to
  gas gangrene
• Protease and toxin activity are apparent in
  wound.
• Alpha-toxin (phospholipase C or lecithinase)
• Theta toxin hemolytic and necrotizing effects
• Spreading factors DNAse, collagenase and
  hyaluronidase

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• C. perfringens also produces an enterotoxin and
  is an important cause of food poisoning.

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• Double zone hemolysis
• lecithinase , motile -
• C.perfringens A-E
• Food poisoning type A
• enteritis necroticans type C beta-toxin to
  damage intestinal villi
• gas gangrene

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Treatment

• Treatment Pen G, tetracycline, antitoxin
• Passive anti-alpha toxin theraphy
• Hyperbaric oxygen is another form of wound
  treatment.
• Drainage and debridement are used to expose
  tissues to aerobic condition.

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Clostridium perfringens
B

• A

A. Double zone hemolysis on BRU/BA B. Gram
positive bacilli, car-box shaped
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??????????? C. perfringens
Common
Rare

• Enterotoxin producing type A
  beta-toxin producing type C

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?????????????????????????
???????????, ????????????
???????????????
???????????
???????????, ?????????? trypsin
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????? enterotoxin ???????????
????? beta-toxin ???????????
- ????????????????????? - ???????????????????? -
?????????????
Acute necrotinizing
Disease (pig-bel) - ??????? - ????????????? -
???????? 50
????????
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Clostridium tetani

• the causative agent of tetanus.
• organism is found in soil and in the intestinal
  tracts and feces of various animals.
• produces terminal spores giving it a distinctive
  drumstick appearance.
• a typical Gram-positive cell wall, it may stain
  Gram-negative or Gram-variable, especially in
  older cells.
• tetanus toxin or tetanospasmin

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A
B

• A Stained pus from a mixed anaerobic infection.
• B Electron micrograph of Clostridium tetani
  cells.

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Pathogenesis

• The toxin is produced during cell growth,
  sporulation and lysis.
• sites of action central nervous system.
• spasms and rigidity of the voluntary muscles.
• "lockjaw" involves spasms
• of the masseter muscle.

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Pathogenesis of tetanus caused by C. tetani
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Toxin action

• Tetanospasmin heat labile toxin,150kDa, AB type
  toxin, A bind tissue, B toxic effect
• initially binds to peripheral nerve terminals.
• transported within the axon and across synaptic
  junctions until it reaches the CNS
• becomes rapidly fixed to gangliosides at the
  presynaptic inhibitory motor nerve endings, and
  is taken up into the axon by endocytosis.

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Toxin action (cont.)

• block the release of inhibitory neurotransmitters
  glycine and gamma-amino butyric acid (GABA)
• If nervous impulses cannot be checked by normal
  inhibitory mechanisms, it produces the
  generalized muscular spasms characteristic of
  tetanus.

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Immunity

• usually does not confer immunity, since even a
  lethal dose of tetanospasmin is insufficient to
  provoke an immune response.
• Prophylactic immunization is accomplished with
  tetanus toxoid, as part of the DPT vaccine or the
  DT (Td) vaccine.

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Treatment

• Penicillin
• Remove necrotic tissue
• Muscle relaxants, sedation and assisted
  ventilation are supportive therapy

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Clostridium botulinum

• forms subterminal endospores.
• widely distributed in soil, sediments of lakes
  and ponds, and decaying vegetation
• The botulinum toxins are designated A, B, C1, D,
  E, F, and G.
• Botulism is not spread from one person to
  another.

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Three categories of Botulism

• 1. Classical food-borne Botulism
• 2. Wound botulism
• 3. Infant botulism

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Food-borne botulism

• Home canned foods with low acid content
• symptoms occur 18-36 hr nausea, vomiting, double
  vision, paralysis, respiratory failure and death
  (rate 75 for type A)
• neurotoxin binds to nerve synapse and blocks
  release acetylcholine

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Wound botulism

• This type of botulism is caused by a botulism
  toxin that is produced from a wound that was
  contaminated with Clostridium botulinum.

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Infant botulism

• This type of botulism occurs when infants consume
  spores of Clostridium botulinum, which then
  release toxins in the intestines.
• Most common, associated with honey, floppy baby,
  Sudden infants death syndrome (SIDS)

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Pathogenesis of botulism caused by C. botulinum
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How does botulinum toxin work?
- Normally, muscle contraction is stimulated by
a chemical called acetylcholine. - In some
diseases, such as cerebral palsy, too much
acetylcholine is released, overstimulating the
muscle and resulting in muscle spasm. - Botulinum
toxin releases muscle contraction by inhibiting
acetylcholine release.
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Normally when a message comes from the nerve, Ach
is released and the muscle contracts
When botulinum toxin is added, the release of Ach
is reduced and the muscle stays relaxed.
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How botox works?
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Botox Cosmatic/medical application
Toxin A
Before
After
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Diagnosis

• Spinal Tap (Also called a lumbar puncture)
• A small amount of cerebral spinal fluid
  (CSF) can be removed and sent for testing to
  determine if there is an infection or other
  problems.
• Test for botulism toxin in the patients serum or
  stool

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Prevention

• proper food handling and preparation.
• spores survive boiling (100 OC at 1 atm) for
  more than one hour.
• Because the toxin is heat-labile boiling or
  intense heating (cooking) of contaminated food
  will inactivate the toxin.
• Antitoxin effective against toxin types A-E

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Treatment

• No antibiotic give except in infant botulism
• Potent trivalent (A,B,E) antitoxin

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Clostridium difficile

• Major cause of antibiotic-associated diarrhea and
  pseudomembranous colitis
• motile , gelatin , casein
• C.difficile toxin A, B (heat and acid labile)
• toxin A enterotoxin
• toxin B cytotoxin cell damage

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Pathogenisis of pseudomembranous colitis cause by
C. defficile
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• leukocytosis in feces 30,000-50,000 cells/ml
• Prior symptoms acute diarrhea, electrolyte loss,
  nausea, sepsis, shock and death
• Nosocomial infection
• Treatment vancomycin

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Non-sporeforming, gram negative bacilli

• normal flora in GI tract of human and animal
• Bacteroides fragilis group, Fusobacterium,
  Porphyromonas, Prevotella, and etc.
• some species of Prevotella and Porphyromonas
  produce a dark pigment

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A B
A. Bacteroides fragilis B. Fusobacterium nucleatum
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Bacteroides fragilis group

• Gram negative, pleomorphic bacilli
• Resistance to PenG, Cephalosporin, tetracycline
• produce beta-lactamase
• bile-tolerant

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Pathogenicity

• Adherence ??????????? agglutinate ??? RBC
  ??????????? fimbriae-like
• Capsule acidic polysaccharides, ??????????
  phagocytosis ??? WBC
• Enzymes collaginase, protease, hyaluronidase,
  fibrinolysin, Dnase,, etc.
• Endotoxins (LPS) activate C3 pathway,
  ??????????????????? PMNs ????

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• Beta-lactamase production
• B. fragilis protect themselves and other
  species in mixed infections
• Superoxide dismutase production
• Protects bacteria from toxic O2 radicals as they
  move out of usual niche

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Fusobacterium

• Delicate gram (-) rods
• Tapering ends
• F. nucleatum
• Mouth, Upper Resp. tract, GI tract, Genital tract
  
• Head, neck and lower respiratory tract infections
• F. necrophorum
• Anaerobic tonsillitis/pharyngitis
• Involve jugular vein ? Sepsis
• Liemeres Disease

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Prevotella Porphyromonas

• Small, pale staining coccobacillary gram (-) rods
• Dental plaque and gingival crevices
• Infections of oral cavity and upper respiratory
  tract

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Anaerobic gram positive cocci

• Family Peptococcaceae
• Rearrangement single, pairs, chains
• motile - , flagella - , endospore -
• colonies size from 0.5-2 mm in diameter
• Susceptible PenG, Clindamycin,
• Chloramphenicol, Cephalosporin

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• Normal flora in mouth, URT, large intestine, GU
  and skin
• Sensitive to Sodium polyanethol sulfonate (SPS, gt
  12 mm) Peptostreptococcus anaerobius
• indole in P. asaccharolyticus

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Non-sporeforming, gram positive bacilli

• Actinomyces, Propionibacterium
• Actinomyces found sulphur granule in pus,
  Actinomycosis
• P.acnes resident flora at skin, sometimes
• contaminated in blood
• culture, endocarditis
• ? acne

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Anaerobic Gram Positive Non-sporeforming Bacilli

• Bifidobacterium
• Lactobacillus
• Nl flora of gut and vagina
• Ferments glucose to lactic acid (vaginal pH lt5)
• Mobiluncus
• Eubacterium

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ACTINOMYCES

• Anaerobic, filamentous, gram positive bacillus
• Exhibit true branching
• Mykes Greek for fungus
• Thought by early microbiologist to be fungi
  because of
• Morphology
• Disease they cause

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ACTINOMYCOSIS

• Not highly virulent (Opportunist)
• Component of Oral Flora
• Periodontal pockets
• Dental plaque
• Tonsilar crypts
• Take advantage of injury to penetrate mucosal
  barriers
• Coincident infection
• Trauma
• Surgery

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ACTINOMYCOSIS

• Form indurated masses with fibrous walls and
  central loculations with pus
• Pus contains "Sulfur Granules"
• Gritty, yellow white
• Average diameter - 2mm
• Composed of mineralized mycelial mass
•  
• Chronic infection
• Form burrowing sinus tracts to skin or mucus
  membranes
• Discharge purulent material

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Actinomycosis - sulfur granule
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Pulmonary Actinomycosis

• 15 of cases
• Aspiration of organism from the oropaharynx
• Slowly progressive process involving lung and
  pleura
• May be mistaken for malignancy
• Chest pain, fever, wgt loss and hemoptysis

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• Gram postive spore-forming rods
• Clostridium - obligate anaerobes normally
  exogenous however C. difficile andC. perfringins
  may be found in the bowel flora
• C. botulinum-produces neurotoxin which acts on
  pre-synaptic cholinergics
• C. tetani - neurotoxin that inhibits glycine (an
  inhibitor itself). Also produces the hemolysin
  tetanolysin.

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• C. perfringins-toxin phospholipase C (or
  lecithinase) egg yolk medium isthe assay for
  lecithinase or lipase activity
• C. difficile - cytotoxin is responsible for
  ulcerative colitis

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• Gram negative rods
• Bacteriodes fragilis - known for its
  polysaccharide capsule which is anti-phagocytic
• B. melaninogenicus - utilizes hemin in
  blood-containing media and deposits a black
  pigment (which is not melanin). It is most
  frequently found in the oral cavity and works
  synergistically in fusospirochetal disease and
  advanced peridontitis produces enzymes and
  chronic inflammation.
• Fusobacterium necrophorum- distinguished from
  Bacteroides on the basis of end products - also
  produces enzymes that allow it to be invasive.

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• Gram positive cocciPeptostreptococcus -
  frequently involved in respiratory infections

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• Gram positive non-spore-forming rods-- not
  necessarily obligate anaerobes, but may be
  capnophilic (utilizing carbon monoxide)Actinomyce
  tes - produces the actinomycoses, involved in
  chronic infections, particularly localized
  respiratory infections

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• Gram negative cocciVeillonella (not usually
  pathogenic)