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TUBERCULOSIS

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					TUBERCULOSIS




     Dr. Mohammed Farouq
ETIOLOGY

    Mycobacterium tuberculosis
    Mycobacterium avium
    Mycobacterium bovis [rare]
CHARACTERISTICS

    curved  rods
    obligate aerobes
    acid-fastness
EPIDEMIOLOGY

   High Risk Factors:
    – Infants
    – overcrowding and bad hygiene
    – Immunosuppresive states
        lymphoma
        viral illness: measles, HIV
        drugs eg. steroids
TRANSMISSION

   Person to person
   Inhalation of
    contaminated
    droplets from an
    infected adult
INCUBATION PERIOD

   2 - 8 weeks
INFECTIVITY (source of infection)

    Adolescents and   adults
    Young children (rare)
      – Tubercle bacilli are sparse in the
        endobronchial secretions
      – cough is weak or absent
CLINICAL MANIFESTATIONS
INFECTION (Latent TB Infection)

    Preclinical stage  of infection
      – No clinical features
      – Normal CXR
      – PPD-positive only
DISEASE (Active TB)

    Clinicalmanifestations are present
    (Symptoms and signs or chest x-ray
     findings)
Pulmonary Disease
Primary Pulmonary Disease

   Hilar adenopathy
   Primary (‘Ghon’)complex
        Parenchymal       focus
          –   70% subpleural
          –   Localized, nonspecific infiltrate
        Regional    lymphadenitis
          –   hilar adenopathy
          –   Asymptomatic
          –   Nonproductive cough and mild dyspnea
          –   Some infants have failure-to-thrive
Complicated Primary Pulmonary Disease

     Parenchyma
        Progressive     Primary Pulmonary Disease
             High fever
             severe cough with sputum production
             weight loss, and night sweats ( common)
             diminished breath sounds, crepitations
Complicated Primary Pulmonary Disease

     Regional      lymph nodes
     Tracheobronchial lymph          node disease
       –   focal hyperinflation  wheezing
       –   atelectasis
     Endobronchial       disease
       –   collapse-consolidation or segmental tuberculosis
Complicated Primary Pulmonary Disease

   Pleural Effusion
         6-12 months after the infection
         usually > 6 years
         Asymptomatic local pleural effusion with
          primary disease
         Larger effusions occur later
         radiographic resolution often takes months.
         The tuberculin skin test is positive in 70–80%
          of cases
         The prognosis is excellent
Reactivation Tuberculosis

       Rare in children, localized to the lungs (upper lobes)
       Fever, malaise, weight loss, night sweats, productive
        cough, chest pain
       Physical examination findings usually are minor or
        absent,
       Highly contagious
Systemic Disease
Miliary tuberculosis

     2–6 mo after the primary infection
     common in infants and young children
     onset is insidious or acute
     anorexia, weight loss
     low-grade fever later high
     lymphadenopathy &hepatosplenomegaly(50%)
     progressive pulmonary disease
       –   (respiratory distress, pneumothorax,
           pneumomediastinum)
Miliary tuberculosis

     meningitis(20–40%)
     Choroid tubercles occur in 13–87%


        tuberculin skin test is nonreactive in up to
     The
     40%

     Early sputum or gastric aspirate cultures have
      a low sensitivity.
     Biopsy of the liver or bone marrow offer better
      yield
Adenopathy
TB adenitis

     within   6–9 months
          – tonsillar, anterior cervical, submandibular, and
            supraclavicular nodes
          – epitrochlear, axillary, inguinal
               early: firm, discrete, nontender

               later: matting, feel fixed to underlying or
                overlying tissue
       The tuberculin skin test is usually reactive.
       The chest radiograph is normal in 70% of cases.
       Culture of lymph node tissue yields the organisms in
        about 50%
TB adenitis

     Differential diagnosis
       –   pyogenic infection
       –   nontuberculous mycobacteria (NTM)
       –   cat-scratch disease
       –   Toxoplasmosis
       –   Tumor
       –   branchial cleft cyst
       –   cystic hygroma
CNS Disease
Meningitis

   Common in children between 6 mo and 4 yr
    of age.
   Gradual onset.
   Lethargy, headache, vomiting, seizures.
   Cranial nerve palsies, focal neurologic signs.
   decerebrate posturing, death.
Meningitis

   The tuberculin skin test is nonreactive in up
    to 50%
   20–50% of children have a normal chest
    radiograph
   CSF analysis
     – Leukocyte count 10 to 500 cells/mm3
       (lymphocytes)
     – Glucose less than 40 mg/dl
     – Protein level is elevated
Tuberculomas

   The tuberculin skin test is usually reactive
   Chest radiograph is usually normal
   Surgical excision
   Corticosteroids
   CT scan or MRI of the brain
   Angiographic studies (avascular)
Other Systems

      Abdominal T.B
        – Peritonitis
        – Mesenteric adenitis: obstruction, perforation
        – malabsorption, fistula formation,
      Bone and Joint Disease
         – spine  Pott’s disease
         – Hip, knee
    Cutanenous
    Ocular
DIAGNOSIS

    History
    Physical  examination
    Tuberculin Skin Tests
     ( Mantoux tuberculin skin test)
    Demonstration of Acid Fast Bacilli
       – (Ziehl-Neelsen stain)
    Culture
       – sputum/gastric washings
       – Pleural fluid, CSF, urine
       – Biopsy material
DIAGNOSIS

    Radiological Examination
       – CXR, CT, MRI, IVP
    Increased ESR, anemia, lymphocytosis
    QuantiFERON (LTBI)

    POLYMERASE CHAIN REACTION (PCR)
          employs a DNA probe
          only for smear-positive respiratory tract
            secretions
          sensitivity is similar to that for culture.
     Classification System for TB
Class         Type                     Description

 0      No TB exposure           No history of exposure
        Not infected             Negative reaction to tuberculin skin test


 1      TB exposure              History of exposure
        No evidence of infection Negative reaction to tuberculin skin test

 2      TB infection              Positive reaction to tuberculin skin test
        No disease                Negative bacteriologic studies (if done)
                                  No clinical, bacteriological, or radiographic
                                  evidence of active TB

 3      TB, clinically active    M. tuberculosis cultured (if done)
                                 Clinical, bacteriological, or radiographic
                                 evidence of current disease

 4      TB                       History of episode(s) of TB
        Not clinically active                 or
                                 Abnormal but stable radiographic findings
                                 Positive reaction to the tuberculin skin test
                                 Negative bacteriologic studies (if done)
                                              and
                                 No clinical or radiographic evidence of
                                 current disease
 5      TB suspected             Diagnosis pending
Tuberculin Skin Test (PPD)

     intradermal  injection of 0.1 ml.
     Containing 5 tuberculin units (TU) of purified
      protein derivative (PPD) stabilized with Tween
      80.
     The amount of induration in response to the
      test should be measured by a trained person
      48–72 hr.
PPD-Host-related Factors

   Very young age.
   Malnutrition.
   immunosuppression.
   Overwhelming tuberculosis.
   Corticosteroid therapy.
   10%-50% of those with meningitis or
    disseminated disease.
   Poor technique or misreading the results.
False-positive reactions

     cross-sensitizationto antigens of
      nontuberculous mycobacteria (NTM)
     Previous vaccination with BCG( < 10
      mm of induration)
Interpretation Of The PPD Skin Test

     epidemiologic    factors
     Host   factors
Interpretation Of The PPD Skin Test

    >5 mm Induration  POSITIVE
       For adults and children at the highest risk of infection
          – recent contact with infectious persons
          – clinical illnesses consistent with
            tuberculosis
          – HIV infection or other immunosuppression
Interpretation Of The PPD Skin Test

    >10 mm Induration  Positive
       children less than 3 yr of age
Interpretation Of The PPD Skin Test

    >15 mm Induration -> Positive
       For low-risk persons, especially those residing in
        communities where the prevalence of tuberculosis is low
        Administering the Tuberculin Skin Test


• Inject intradermally 0.1 ml of 5
  TU PPD tuberculin

• Produce wheal 6 mm to 10 mm
  in diameter

• Do not recap, bend, or break
  needles, or remove needles from syringes

• Follow universal precautions for infection control
          Reading the Tuberculin Skin Test


• Read reaction 48-72 hours after
  injection

• Measure only induration

• Record reaction in millimeters
TREATMENT

     USE MULTIPLE DRUGS
     Bactericidal Drugs
       –   Isoniazid,
       –   rifampin,
       –   Streptomycin
       –   Pyrazinamide
     Bacteriostatic Drugs
       –   ethambutol at low doses
       –   ethionamide
       –   cycloserine
ISONIAZID (INH).

      daily dose of 10 mg/kg
      metabolized by acetylation in the liver
         – Peripheral neuritis
         – Hepatotoxicity
         – increase phenytoin levels
         – interacts with theophylline
         – hemolytic anemia in patients with glucose-6-
           phosphate dehydrogenase deficiency
         – lupus-like reaction with skin rash and arthritis.
RIFAMPIN (RIF)

      orange discoloration of urine and tears
      gastrointestinal disturbances
      hepatotoxicity
      thrombocytopenia
      influenza-like syndrome
      render oral conceptives ineffective
      interacts with several drugs, including quinidine, sodium
       warfarin, and corticosteroids
PYRAZINAMIDE (PZA)

      30 mg/kg/24 hr
         – Arthralgias
         – arthritis, or gout
         – hepatotoxicity
STREPTOMYCIN (STM).

      given intramuscularly
      when initial INH resistance is suspected
      when the child has a life-threatening form of tuberculosis
         – Toxicity to the vestibular and auditory portions
           of the 8th cranial nerve.
         – Renal toxicity
      contraindicated in pregnant women
ETHAMBUTOL (EMB)

       25 mg/kg/24 hr EMB has some bactericidal activity
      treatment of drug-resistant disease
        –   optic neuritis
OTHER DRUGS

     Aminoglycosides (kanamycin and amikacin)
     Capreomycin
     Cycloserine
     Ciprofloxacin and ofloxacin are fluoroquinolones
Pulmonary tuberculosis

      6 mo of INH and RIF
      supplemented during the first 2 mo by PZA
      administration be directly observed
      If community rate of INH resistance > 5–10%
          – add a 4th drug— STM, EMB, or ETH
Extrapulmonary tuberculosis

     same as for pulmonary tuberculosis
     9–12 mo
       – bone and joint tuberculosis
       – Tuberculous meningitis
Drug-Resistant Tuberculosis

    Types of drug resistance
      – Primary resistance
      – Secondary resistance
Treatment For Drug-Resistant
Tuberculosis

     at least three and usually four or five drugs
      should be administered initially
     for INH-resistant tuberculosis
        – Treat for 9 months with RIF, PZA, and EMB
     INH and RIF resistance are present
        – Treat for 12–18 months
Corticosteroids

       tuberculous meningitis
       endobronchial tuberculosis
       pericardial effusion
       pleural effusion
       severe miliary tuberculosis

       prednisone 1–2 mg/kg/24 hr in 1–2 divided doses for 4–
        6 wk with gradual tapering.
Supportive Care

      Adequate nutrition
      REGULAR FOLLOWUP
TREATMENT OF LTBI

   9 mo of daily INH therapy
PREVENTION

   Bacille Calmette-Guérin Vaccination
      intradermal injection
         – Local ulceration
         – regional suppurative adenitis occur in 0.1–1%
         – Osteitis is a rare
         – disseminated BCG infection
       BCG is 50%–80% effective in disseminated and
       meningeal tuberculosis

				
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posted:12/21/2011
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