The American Thoracic Society (ATS), Centers for Disease Control and Prevention (CDC), and Infectious Diseases Society of America (IDSA) developed an algorithm for the treatment of a patient with possible tuberculosis and negative initial smears.
Patient selection:
(1) risk factors for tuberculosis
(2) positive tuberculin skin test
(3) abnormal chest X-ray and/or clinical symptoms
(4) negative sputum smears for acid fast bacilli (AFB)
(5) no other diagnosis
If the initial cultures are positive, then the person needs to be treated for active tuberculosis.
The differential diagnosis if the initial cultures are negative:
(1) active, culture-negative tuberculosis
(2) inactive tuberculosis
Parameters:
(1) suspicion for tuberculosis
(2) change in chest X-ray and clinical symptoms after initial 2 months
Level of Suspicion for Tuberculosis |
Therapy During First 2 Months |
Change After 2 Months |
Subsequent Management |
high |
4 drug regimen (see below) |
none |
treatment complete (see note) |
high |
4 drug regimen (see below) |
improvement |
2 months INH and RIF |
low |
none |
none |
one of 3 regimens (below) |
The 4 drug regimen includes:
(1) isoniazid (INH)
(2) rifampin (RIF)
(3) ethambutol (EMB)
(4) pyrazinamide (PZA)
NOTE: A multidrug-resistant strain of tuberculosis might not show improvement after 2 months of the 4 drug regimen.
Possible drug regimens for the patient with a low suspicion for active tuberculosis:
(1) rifampin plus pyrazinamide for 2 months
(2) rifampin with or without isoniazid for 4 months
(3) isoniazid for 9 months
Specialty: Infectious Diseases, Pharmacology, clinical, Pulmonology