TB Flashcards
5 Stages of Pulmonary Pathology of TB
- TB Bacilli 1-Smm in alveolar macrophage
- once inside, the Macrophage destroys or uninhibited
Scavenging non activated alveolar macrophages
5 Stages of Pulmonary Pathology of TB
- Caseous necrosis has tendency to liquefy
- Discharges into the airways & spread to other parts of the body
Liquefaction
5 Stages of Pulmonary Pathology of TB
- Weak CMI
> Enlargement of Tubercle with hematogenous dessimination - Strong CMI
> stabilization & regression of tubercle
CMI
5 Stages of Pulmonary Pathology of TB
- Inhibited by CELL MEDIATED immunity
- (CMI) & Delayed type hypersensitivity (DTH)
- infected macrophages present TB antigens to T lymphocytes
- necrosis
Logarithmic increase in the # of bacilli
5 Stages of Pulmonary Pathology of TB
- Macrophage fails to destroy the bacilli, bacilli undergoes replication
- More bacilli accumulate in the developing lesion “tubercle or granuloma”
Symbiosis
- a child has had significant contact (“shared the air”) with an adult or adolescent with infectious tuberculosis but lacks proof of infection.
- In this stage, the tuberculin skin test (TST) or interferon-y release assay (IGRA) result is negative, the chest radiograph is normal, the physical examination is normal, and the child lacks signs or symptoms of disease
TB Exposure
- patient inhales the bacilli surviving intracellularly w/in lung assoc lymphoid tissue
— HALLMARK: (+) TST or IGRA
— Child has no signs & symptoms, PE normal,
— CXR: +/- granuloma or calcifications in the lung or normal
***lmmunocompetent adult with untreated LTBI:
5-10% lifetime risk of developing dse
***Infected child <lyo: 40% develop dse within 9 mos.
TB INFECTION:
- can be local or general
- originate in the discharge of bacilli into the pleural space from a subpleural pulmonary focus or caseated lymph node.
- Asymptomatic local: common in primary tuberculosis & part of the primary complex.
- Larger and clinically significant effusions occur months to years after the primary infection.
- Uncommon in children younger than 6 yr of age
- Rare in children younger than 2 yr of age
- Unilateral but can be bilateral
TUBERCULOUS PLEURAL EFFUSION
Clinical Manifestations & LAB
- Clinical onset
- Fever
- TST
- pleural fluid
- specific gravity
- protein level
- glucose conc.
- WBC
- Acid-fast smears
- culture
- biopsy
- Clinical onset: often sudden, characterized by low to high fever, shortness of breath, chest pain on deep inspiration, and diminished breath sounds.
- Fever and other symptoms can last for several weeks after the start of antituberculosis chemotherapy.
- The TST is positive in only 70-80% of cases.
- pleural fluid is usually yellow and only occasionally tinged with blood.
- Specific gravity is usually 1.012-1.025
- protein level is usually 2-4 g/dL
- the glucose concentration may be low, although it is usually in the low-normal range (20-40 mg/dL).
- Increased WBC: early predominance of polymorphonuclear cells followed by a high percentage of lymphocytes
- Acid-fast smears of the pleural fluid are rarely positive.
- Cultures of the fluid are positive in <30% of cases.
- Biopsy of the pleural membrane is more likely to yield a positive acid-fast stain or culture, and granuloma formation
TB symptomatic or PRESUMPTIVE TB (for less than 15 years old): 3 or more of the following symptoms:
- cough/ wheezing
- fever
- antibiotic response
- follow-up
- physical acitivties
- > 2 weeks cough/wheezing
- > 2 weeks unexplained fever
- Failure to respond after 2 weeks on appropriate antibiotic for LRTI
- After 2 weeks of Viral infection or Exanthem (ex measles), failure to regain previous state of health
- Loss of appetite, wt loss, failure to gain wt or wt faltering
- Fatigue, reduced playfulness or lethargy
TB symptomatic or PRESUMPTIVE TB (for MORE than 15 years old): 3 or more of the following symptoms:
Cough of at least 2 weeks duration with or without the following symptoms:
- Significant and unintentional weight loss
- Fever
- Bloody sputum (hemoptysis)
- Chest/back pains not referable to any musculoskeletal disorders
- Easy fatigability or malaise
- Night sweats
- Shortness of breath or difficulty of breathing
2. Unexplained Cough of any duration in:
- A close contact of a known active TB case;
- High-risk clinical groups (e.g., HIV/AIDS, diabetes, end-stage renal disease, cancer connective tissue diseases, autoimmune diseases, silicosis, patients who underwent gastrectomy or solid organ transplantation and patients on prolonged systemic steroids)
- High risk populations (e.g., elderly, urban poor, inmates and other congregate settings)
Wallgren’s timetable of TB
Manifestation can be predicted:
• Pumonary-
• Miliary, Tb Meningitis, disseminated TB:
• TB adenitis:
• Bones & joints:
• Renal:
Pumonary-months after primary infection
• Miliary, Tb Meningitis, disseminated TB: 2-6mos
• TB adenitis:3-9 mos
• Bones & joints: 1 year
• Renal: 5-25 yrs
TST POSITIVE:
> 5mm if with history of close contact with known/suspected case of TB, clinical findings suggestive of TB, chest x-ray suggestive of tb & immunocompromised patients
Lab Test for child more than 5 years old or can expectorate
Sputum collection
Lab procedure For child less than 5 years old or cannot expectorate
Gastric Washing collection
- Primary diagnostic toll in NTP case finding
- The only contraindication to collecting is massive hemoptysis which is expectoration of large volumes of blood (200-600 ml in 24 hours) from the respiratory tract. A Blood streaked can still be examined.
Sputum exam/ DSSM (5-10ml)
- are not as sensitive as sputum cultures1
- At least 5000 to 10,000 bacilli per mL are needed for detection of bacteria in stained smears;
• In contrast, 10-100 organisms are needed for a positive culture
AFB Smear
AFB Smear false positive results caused
by the presence of nontuberculous mycobacteria
can occur
should not be used for the diagnosis of Pulmonary or extrapulmonary TB nor for diagnostic work-up of adults and children suspected of active TB, irrespective of HIV status
Interferron Gamma Release Assay
- is the first fully automated cartridge-based NAAT for TB
• It is simplifies molecular testing by fully integrating and automating three processes (sample preparation, amplification & detection)
• This real time PCR based molecular test can simultaneously detect TB bacteria & Rifampicin resistance in clinical specimens outside conventional laboratory settings in less than 2 hours.
Xpert MTB/Rif (NAAT)
EXTRAPULMONARY TB
- most common
- most fatal
• Most common :Lymphatic, pleural, Bone TB
• Most fatal: pericardial, meningeal & Miliary
Clues to suspect EXTRAPULMONARY TB
• Monoarticular joint inflammation, negative cultures
• Persistent sterile pyuria
• Unexplained pericardial effusion, constrictive pericarditis, calcifications
• Vertebral Osteomyelitis involving the thoracic spine
• Ascites with lymphocytic predominance,negative cultures
• Chronic lymphadenopathy (cervical)
• CSF lymphocytic pleocytosis with elevated protein & low glucose
• Exudative pleura effusion, lymphocyte predominance, negative cultures.
- MOST common form of Extrapulmonary in children
– Unilateral, can be bilateral
– Supported w/ + PPD, + FNAB/Excision biopsy & CS
– Painless, firm,discrete, movable, become adherent to each other & anchored to the surrounding tissues as they enlarge
Cervical LAD(scrofula), Tb adenitis
