Mycobacterial Infections Flashcards
Acute cough exists for less than?
Whats it most commonly due to?
Subacute cough is how long?
Chronic cough is longer than what?
Three weeks
most commonly due to an acute respiratory tract infection, PE, pneumonia
3-8 weeks
8 weeks
HOw is TB charcterized pathologically?
6
- by inflammatory infiltrations,
- formation of tubercles, caseation,
- necrosis,
- abscesses,
- fibrosis, and
- calcification
What kind of pts account for 30-50% of the increase in TB?
HIV infected pts
Why do we do an acid fast stain?
Contains mycotic acid and needs the acid fast
Inhalation and deposition in the lungs leads to one of four possible outcomes. What are they?
4
- Immediate clearance of the organism
- Chronic or latent infection
- Rapidly progressive disease (or primary disease)
- Active disease many years after the infection (reactivation disease)
People with untreated active TB will die within how many years?
50% die 2 years
Chronic or Latent Infection
of TB is what?
3
This is the person that comes in with a positive PPD but who is asymptomatic, with a clear CXR.
Pathogenesis of TB?
3
- Small bacilli carried in droplets small enough (5 to 10 µm) to reach the alveolar space
- Bacilli proliferate inside alveolar macrophages and kill the cells
- Infected macrophages produce cytokines and chemokines that attract other phagocytic cells, which eventually form a nodular granulomatous structure called the tubercle or
Gohn Focus
What phagocytic cells do the TB infected macrophages attract with cytokines and chemockines?
3
- monocytes,
- other alveolar macrophages, and
- neutrophils
IF the bacterial replication is not controlled what happens?
What does this lead to?
2
tubercle enlarges and the bacilli enter the local draining lymph nodes
lymphadenopathy, a characteristic manifestation of primary TB
Caseation(cell necrosis-looks like cheese)/fibrosis/calcification
Ghon complex
What stage determines if the pt will have primary disease or chronic or latent TB?
Initial inflammatory granulomatous tubercle formation
–If bacterial replication is controlled here, patient will NOT develop primary disease and is said to have chronic or latent infection
What is the Ghon complex?
eponym which describes an inflammatory nodule in the pulmonary parenchyma (Gohn focus) with an accompanying hilar adenopathy, in line with lymphatic drainage from that pulmonary segment
Enlargemnt of tubercle and infiltration of lymph system!!
Frontal chest radiograph shows a calcified right lung nodule with associated calcified hilar lymph nodes.
What is this describing?
Ghon complex
end is that the complex becomes calcified
In those who develop active disease within the first two to three years after infection, it will cause severe illness. Including?
2
Lung necrosis
Extrapulmonary
Main symtpoms of pulmonary TB:
CNS?2
Lungs?3
Skin?2
- appetite loss and fatigue
- CHest pain, coughing up blood, productive prolonged cough
- night sweats, pallor
Where does the infection proliferate?
inside the alveolar macrophages
Whats the distinct lymphadenopathy you would identify in TB?
Hilar lymphadenopathy
(need to look for this on an XRAY)
Can be calcified noduels in the lung/apex and in the hilar region
HOw does Secondary infection/Reactivation occur?
4
(what is important to note here?)
What is the bacteria doing in a reactivation infection?
- Asymptomatic primary infection occurs!!!!
- Cell-mediated immunity
- Dormancy
- Then, recurrance may occur
Results when the persistent bacteria in a host suddenly proliferate
(immunocomprimised)
Secondary/Reactivation is Clearly associated with immunosuppression and can be seen in the following circumstances?
5
- HIV infection and AIDS
- End-stage renal disease
- Diabetes mellitus
- Malignant lymphoma
- Corticosteroid use
In contrast to primary disease, the disease process in reactivation TB tends to be what?
What is there little of compared to a primary infection?
Where do the lesions in secondary infections usually occur?
Localized (ghon region is reactivated)
there is little regional lymph node involvement and
the lesion typically occurs at the lung apices
Symptoms of Secondary/Reactivation infection?
6
- Cough, hemoptysis
- Persistent fever/night sweats
- Weight loss
- Malaise
- Adenopathy
- Pleuritic chest pain
What is Miliary Tuberculosis?
If the bacterial growth continues to remain unchecked, the bacilli may spread hematogenously to produce disseminated TB
miliary TB is now used to denote ALL forms of progressive, widely disseminated hematogenous tuberculosis, even if the classical pathologic or radiologic findings are absent.
Acute miliary TB presents how?
2 early
3 late
Who does it tend to infect?
- High fevers
- Night sweats
- Occ. Resp distress
- septic shock,
- multiorgan failure
young pts
Chronic miliary TB presents how?
3
Who does it tend to infect?
- Fever
- Anorexia
- Weight loss
Particularly in the elderly (FTT)
Extrapulmonary Manifestations of TB?
6
Frequency? History? Imagining? Most commonly infection type? Treatment?
- Frequency is increasing
- Past history is unreliable
- 50% have normal chest radiographic findings
- Clinical features vary widely
- Most common type is infection of an individual organ system
- In most cases, same regimens used for pulmonary TB are used
Extrapulmonary Manifestations:
PLaces where it can move to and affect?
7
- Pleural/Pericardial effusions
- Lymph node infection! (Scrofula)
- Kidney
- Skeletal (potts- in the spine)
- Joints
- CNS
- Intraabdominal/GI
What kind of infections would be caused by CNS tuberculosis?
3
- Meningitis;
2. Intracranial tuberculoma; 3. spinal tuberclous arachnoiditis
What kinds of Intraabdominal infections can be caused by TB?
4
- GI tract;
- peritoneum;
- renal tuberculosis;
- testicular granuloma
Most common cause of pericardial constriction in other countries?
TB
Most persons diagnosed with TB are begun on specific treatment before the diagnosis is confirmed by the laboratory (why do you think this is true?)
It can take months to grow the organims in the agar so you start it early
What constitutes a positive PPD?
10mm induration
