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Experiment seven Experiment seven
Mycobacterium Mycobacterium
tuberculosistuberculosis
PathogenesisPathogenesis
primary infectionprimary infection
1) lung infection 1) lung infection
secondary secondary infection infection
2) Out lung infection 2) Out lung infection
PULMONARY TUBERCULOSISPULMONARY TUBERCULOSIS
Symptoms:Activation of macrophages -> cytokine secretion, IL-1: fever,
TNF: lipid metabolism, weight loss, tissue necrosis. Oxygen radicals: tissue damages
Tissue necrosis -> inflammation -> mucous secretion, destruction of
blood vessels -> frequent cough and bloody sputum
Who is at risk:Who is at risk:
Primary infection: children Primary infection: children
Secondary infection: age>25 Secondary infection: age>25
MM. . tuberculosistuberculosisGeneral FeaturesGeneral Features
EUGONIC GROWTH 14 DAYS DYSGONIC GROWTH 14 DAYS
Mycobacterium tuberculosis Mycobacterium bovis
COLONIAL MORPHOLOGY OF THE
TUBERCULOSIS COMPLEX MYCOBACTERIA
COLONIAL MORPHOLOGY OF THE COLONIAL MORPHOLOGY OF THE
TUBERCULOSIS COMPLEX MYCOBACTERIATUBERCULOSIS COMPLEX MYCOBACTERIA
ResistanceResistance::
UVMalachite green(1:13000)
Alcohol (to nonspore-forming bacteria)
3%HCL, 6%H2SO4,
4%NaOH (15min)
Heat(62-63℃,15min)Chemical disinfectants (more)
WetDry (highly)
SensitiveNot sensitive
EUGONIC GROWTH 14 DAYS DYSGONIC GROWTH 14 DAYS
Mycobacterium tuberculosis Mycobacterium bovis
COLONIAL MORPHOLOGY OF THE
TUBERCULOSIS COMPLEX MYCOBACTERIA
COLONIAL MORPHOLOGY OF THE COLONIAL MORPHOLOGY OF THE
TUBERCULOSIS COMPLEX MYCOBACTERIATUBERCULOSIS COMPLEX MYCOBACTERIA
Clinical syndromesClinical syndromes
a. a. fatigue, weakness, weight loss and fatigue, weakness, weight loss and feverfever
b. pulmonary involvement: chronic b. pulmonary involvement: chronic cough,spit bloodcough,spit blood
c. meningitis or urinary tract c. meningitis or urinary tract involvementinvolvement
d. bloodstream dissemination: miliary d. bloodstream dissemination: miliary tuberculosis with lesions in many tuberculosis with lesions in many organs and a organs and a high mortality ratehigh mortality rate..
MYCOBACTERIUM TUBERCULOSIS 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)
DiagnosisDiagnosisThe steps to diagnose TB infection The steps to diagnose TB infection
and disease include: and disease include:
• A medical evaluation that includes A medical evaluation that includes history and risk assessment history and risk assessment
• The tuberculin skin test The tuberculin skin test
• A chest x-ray A chest x-ray
• A bacteriological examination A bacteriological examination
Treatment for TuberculosisTreatment for Tuberculosis
• Treated with a combination of Treated with a combination of multiple drugs for a long period of multiple drugs for a long period of time: rifampin, isoniazid (INH), time: rifampin, isoniazid (INH), pyrazinamide, ethambutol, and pyrazinamide, ethambutol, and streptomycin.streptomycin.Emergence of multi-drug resistant M. tuberculosis strains.
PrinciplePrinciple
While the majority of bacterial While the majority of bacterial organisms are stainable by either organisms are stainable by either simple or Gram-staining procedures, simple or Gram-staining procedures, a few genera, particularly the a few genera, particularly the members of the genus members of the genus Mycobacterium like M tuberculosis, Mycobacterium like M tuberculosis, are resistant and can only be are resistant and can only be visualized by the acid fast method. visualized by the acid fast method. The stain is of diagnostic value in The stain is of diagnostic value in identifying these organisms.identifying these organisms.
PrinciplePrinciple
The characteristic difference between The characteristic difference between mycobacteria and other organisms is the mycobacteria and other organisms is the presence of a thick waxy (lipoidal) wall that presence of a thick waxy (lipoidal) wall that makes penetration by stains extremely makes penetration by stains extremely difficult. Once the stain has penetrated, difficult. Once the stain has penetrated, however, it cannot be readily removed even however, it cannot be readily removed even with the vigorous use of acid alcohol as a with the vigorous use of acid alcohol as a decolorizing agent. Because of this property, decolorizing agent. Because of this property, these organisms are called acid-fast, while all these organisms are called acid-fast, while all other microorganism, which are easily other microorganism, which are easily decolorized by acid alcohol, are non-acid-decolorized by acid alcohol, are non-acid-fast.The acid-fast stain use three different fast.The acid-fast stain use three different reagents as follows:reagents as follows:
Acid-fast stain
1.Prepare a Smear1.Prepare a Smear
Smear Dry Smear Dry FixedFixed
2.Acid-fast stain2.Acid-fast stain
Process of Acid-fast stain
9% carbolfuchsin9% carbolfuchsin acid-acid-alcoholalcohol
(Primary staining)(Primary staining) (Decoloration)(Decoloration)
Methylene blue Methylene blue
(Conterstain)(Conterstain)
Washing
5min5min
1-2min
Washing
Washing
dry the slide with bibulous papers Observation with the oil immersion lensResults :acid-fast bacteria:red color non-acid-fast:blue color
Mycobacterium tuberculosis:red colourMycobacterium tuberculosis:red colourShape:silm rod,o.4×3μm Background and the other bacteria:blue colour
Corynebacterium Corynebacterium diphtheriaediphtheriae
Thick grey ‘pseudomembrane’composed of fibrin, epithelial cells, bacteria and polymorph neutrophils
Pseudomembranemay cause blockage, suffocation
The cervical lymph nodes enlarge causing The cervical lymph nodes enlarge causing oedemaoedemaof the neck (a classical condition of of the neck (a classical condition of ‘‘bullneckbullneck’’))
Largely controlled now by vaccination
However, factors such as poverty and other social factors have led to diphtheria being an endemic/epidemic in many regions of the world
EpidemiologyEpidemiology
Gray-black colonies on Gray-black colonies on telluritetellurite 亚碲酸盐亚碲酸盐 mediummedium
Gram stainGram stain
• PROCEDURE:PROCEDURE:– Smear: Smear: size of a dime to size of a dime to
form a thin filmform a thin film– Dry : Dry : air dryair dry– Fix: Fix: through the warm air through the warm air
above the flame two or above the flame two or three times.three times.
NEISSER’S STAIN and Ⅰ Ⅱ
NEISSER’S STAIN Ⅲ
washing 2min
Blot dry with bibulous papers Observation with the oil immersion lens
30s
Process of Neisser’sStain
Metachromatic granulesMetachromatic granules
•
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