Tuberculosis is the second topic of Sivakumar and Pelly's chapter on tropical diseases in Oh's Manual. It has not been interrogated in the SAQs directly, but it comes up as a differential fairly often.
A good alternative resource is this clinical review article from Critical Care (2013).
- HIV infection
- Chronic renal failure/haemodialysis,
- Solid organ transplant (or bone marrow transplant),
- Gastrectomy (prevents chemical destruction of the swallowed organsim)
- Jejunoileal bypass
- Injecting and inhalational drug abuse
- Prolonged steroid use
- Institutional living conditions (nursing homes, homeless shelters, prisons)
- Urban dwelling
- Poverty, crowding, and lack of access to health care
- Apical lung lesions
- Cough, dyspnoea, haemoptysis
- Hilar lymphadenopathy
- Bronchopleural fistula
- Pleural effusion
Central nervous system disease
- A "thick gelatinous exudate around the sylvian fissures, basal cisterns, brainstem and
- Prodrome lasts 2-8 weeks
- Cranial nerve palsies occur in 20–25% of patients
- Choroidal tubercles may be present (pathognomonic)
- Mortality approaches 50%
ICU emergencies involving tuberculosis
This is present in the Manual as a straight-up point form list, suggesting that it has SAQ importance; eg. List six life-treatening complications of tuberculosis in the ICU patient.
- Massive haemoptysis
- Respiratory failure
- Pericardial tamponade
- Small intestinal obstruction
- Tuberculous meningitis
- Status epilepsy due to tuberculomas
Diagnosis of tuberculosis
- Culture of the bacillus
- Takes a long time
- Also provides drug susceptibility information
- Identification of acid-fast bacilli
- Sputum induction increases rates of TB detection
- It appears to be as good as BAL
- Histological identification of caseating granulomae
- TB PCR in CSF and pleural fluid
- Typical associated CSF findings are high protein, low glucose and predominately lymphocytic CSF.
Nucleic acid amplification
- Rapidly available
- High specificity
- Useful in ruling in rather than ruling out TB.
- If clinical suspicion is high, a negative NAA does not exclude TB.
- NAA results may remain positive for months.
Some important points:
- interferon-γ release assays (IGRAs) cannot discriminate between latent and active TB
- A negative result does not exclude TB and a positive result does not give drug sensitivities.
In this brief summary, one does not even attempt to discuss the management, as it is a complex topic best left to ID professionals. Suffice to say all the drugs you will use will interact with everything, cause organ toxicity, and likely involve some combination of isoniazid, rifampicin, pyrazinamide and ethambutol.
- In-hospital nortality for active TB requiring mechanical ventilation is 33 to 67%.