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Mycobacterium ----Tuberculosis

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					Experiment seven
Mycobacterium
tuberculosis
Pathogenesis

                    primary infection
1) lung infection
                    secondary infection

2) Out lung infection
Who is at risk:


 Primary infection: children
 Secondary infection: age>25
M. tuberculosis
General Features
Clinical syndromes

 a. fatigue, weakness, weight loss and
 fever
 b. pulmonary involvement: chronic
 cough,spit blood
 c. meningitis or urinary tract
 involvement
 d. bloodstream dissemination:
 miliary tuberculosis with lesions in
 many organs and a high mortality
MYCOBACTERIUM TUBERCULOSIS

  Can infect (disseminate) and cause disease
  in many different body locations such as:
  1. Meninges
  2. Brain
  3. Bone
  4. Kidney
  5. Essentially any organ (lung primary target)
 Diagnosis
The steps to diagnose TB infection and
  disease include:
• A medical evaluation that includes
  history and risk assessment
• The tuberculin skin test
• A chest x-ray
• A bacteriological examination
  Treatment for Tuberculosis

• Treated with a combination of multiple
   drugs for a long period of time:
   rifampin, isoniazid (INH), pyrazinamide,
   ethambutol, and streptomycin.
 Emergence of multi-drug resistant M.
  tuberculosis strains.
Principle
   While the majority of bacterial
 organisms are stainable by either simple
 or Gram-staining procedures, a few
 genera, particularly the members of the
 genus Mycobacterium like M
 tuberculosis, are resistant and can only
 be visualized by the acid fast method.
 The stain is of diagnostic value in
 identifying these organisms.
Principle
    The characteristic difference between mycobacteria
     and other organisms is the presence of a thick waxy
     (lipoidal) wall that makes penetration by stains
     extremely difficult. Once the stain has penetrated,
     however, it cannot be readily removed even with the
     vigorous use of acid alcohol as a decolorizing agent.
     Because of this property, these organisms are called
     acid-fast, while all other microorganism, which are
     easily decolorized by acid alcohol, are non-acid-
     fast.The acid-fast stain use three different reagents
     as follows:
Acid-fast stain

  1.Prepare a Smear
  Smear        Dry    Fixed
  2.Acid-fast stain
  Process of Acid-fast stain
                    5min
 9% carbolfuchsin 5                       acid-alcohol
 (Primary staining)Washing
                     m
   (Decoloration) i
                     n                      Washing
                    1-2min

                       Washing            Methylene
   blue
                                          (Conterstain)
dry the slide with bibulous papers
Observation with the oil immersion lens
Results :acid-fast bacteria:red color
         non-acid-fast:blue color
Mycobacterium tuberculosis:red colour
Shape:silm rod,o.4×3μm
Background and the other bacteria:blue colour
Corynebacterium
  diphtheriae
Gray-black colonies on tellurite
亚碲酸盐medium
   Gram stain
• PROCEDURE:
 – Smear: size of a dime to form
   a thin film
 – Dry : air dry
 – Fix: through the warm air
   above the flame two or three
   times.
 Process of
Neisser’sStain
           NEISSER’S STAIN
               Ⅰand Ⅱ

         washing    2min


          NEISSER’S STAIN
                Ⅲ

                      30s


 Blot dry with bibulous papers
 Observation with the oil immersion lens
Metachromatic granules

•

				
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posted:5/26/2013
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