Tuberculosis

Question 1

Tuberculosis

Clinical features

Tuberculosis

• TB affects millions of children worldwide; low but increasing incidence in many developed countries
• Clinical features follow a sequence – primary infection, then dormancy, which may be followed by reactivation to post-primary TB
• Diagnosis is often difficult, so decision to treat is usually based on contact history, Mantoux test, interferon-gamma release assays (IGRA), chest X-ray and clinical features. Young children swallow their sputum, so gastric washings are required
• Adherence to drug therapy can be problematic but is essential for successful treatment
• Contact tracing is important
• TB is more difficult to diagnose and more likely to disseminate in the immunosuppressed.

Answer 1

Presentation:

History:

• HIV infection
• History of a positive purified protein derivative (PPD) test result
• History of prior TB treatment
• TB exposure
• Travel to or emigration from an area where TB is endemic
• Homelessness, shelter-dwelling, incarceration

Classic clinical features associated with active pulmonary TB are as follows:

• Cough
• Weight loss/anorexia
• Fever
• Night sweats
• Hemoptysis
• Chest pain
• Fatigue

Question 2

Tuberculosis

Diagnosis

Answer 2

• Diagnosis of TB in children is even more difficult than in adults. The clinical features of the disease are nonspecific, such as prolonged fever, malaise, anorexia, weight loss or focal signs of infection
• gastric washings on three consecutive mornings are required to visualise or culture acid-fast bacilli originating from the lung#
• Although it is difficult to culture TB from children, the presence of multi-drug resistant strains makes it important to try to grow the organism so that antibiotic sensitivity can be assessed
• The primary screening method for tuberculosis (TB) is Mantoux tuberculin skin test with purified protein derivative (PPD). An in vitro blood test based on interferon-gamma release assay (IGRA) with antigens specific for Mycobacterium tuberculosis can also be used to screen for latent TB infection. IGRA assays offer certain advantages over tuberculin skin testing.

Obtain the following laboratory tests for patients with suspected TB:

• Acid-fast bacilli (AFB) smear and culture - Using sputum obtained from the patient
• HIV serology in all patients with TB and unknown HIV status

Question 3

Tuberculosis

Treatment

Answer 3

• Triple or quadruple therapy (rifampicin, isoniazid, pyrazinamide, ethambutol) is the recommended initial combination
• Once the TB isolate is known to be fully susceptible, ethambutol (or streptomycin, if it is used as a fourth drug) can be discontinued
• After 2 months of therapy (for a fully susceptible isolate), pyrazinamide can be stopped. Isoniazid plus rifampin are continued as daily or intermittent therapy for 4 more months.
• After 2 months of therapy (for a fully susceptible isolate), pyrazinamide can be stopped. Isoniazid plus rifampin are continued as daily or intermittent therapy for 4 more months
• Directly observed therapy (DOT) is recommended for all patients. With DOT, patients on the above regimens can be switched to 2- to 3-times per week dosing after an initial 2 weeks of daily dosing