TB & HIV: An Online Course for Clinicians

Glossary

A

acid-fast bacilli (AFB): Organisms that retain certain stains, even after being washed with acid alcohol. Most acid-fast organisms are mycobacteria. When seen on a stained smear of sputum or other clinical specimen, a diagnosis of tuberculosis should be considered.

adherence: Following the recommended course of treatment by taking all the prescribed medications for the entire length of time necessary.

anergy: The inability to react to a skin test because of a weakened immune system, often caused by HIV infection or severe illness.

B

BACTEC system: Method used for inoculating a liquid medium for growth. When BACTEC is used, results can be obtained within 5 days of inoculation; conventional methods, which use solid media for growth, can take as long as 21 days after inoculation. Faster than conventional methods for determining susceptibility to first-line TB medications.

boosting: A positive reaction to a tuberculin skin test, due to a boosted immune response from a skin test given up to a year earlier; occurs in people who were infected a long time ago and whose ability to react to tuberculin had lessened. Two-step testing is used in TB screening programs to tell the difference between boosted reactions and reactions caused by recent infection (skin test converter).

bronchoscopy: A procedure used to obtain pulmonary secretions or lung tissue with an instrument called a bronchoscope; used only when patients cannot cough up sputum on their own and an induced specimen cannot be obtained.

D

directly observed therapy (DOT): A strategy devised to help patients adhere to treatment; means that a health-care worker or another designated person watches the TB patient swallow each dose of the prescribed drugs.

E

ethambutol (EMB): A first-line drug used to treat TB disease; may cause optic neuritis. Ethambutol should not be given to children who are too young to be monitored for changes in their vision.

G

granuloma: Nodular lesions caused by an organized inflammatory response to the TB bacilli, often becoming calcified.

I

induration: Swelling that can be felt around the site of injection after a Mantoux skin test is done; the reaction size is the diameter of the indurated area (excluding any redness), measured across the forearm (perpendicular to the long axis).

infiltrates: A collection of fluid and cells in the tissues of the lung; visible on a chest x-ray in people with pulmonary TB disease.

isoniazid (INH): The first-line drug that is most often used for preventive therapy and also used to treat TB disease; although relatively safe, it may cause hepatitis and other adverse reactions in some patients.

M

Mantoux tuberculin skin test: The preferred method of testing for TB infection; done by using a needle and syringe to inject 0.1 ml of 5 tuberculin units of liquid tuberculin between the layers of the skin (intradermally), usually on the forearm; the reaction to this test, usually a small swollen area (induration), is measured 48 to 72 hours after the injection and is classified as positive or negative depending on the size of the reaction and the patient’s risk factors for TB.

mediastinal, hilar lymphadenopathy: Swelling of lymph nodes in chest area

miliary disease : TB disease that occurs when tubercle bacilli enter the bloodstream and are carried to all parts of the body, where they grow and cause disease in multiple sites; the chest x-ray of a patient with miliary TB often looks like millet seeds are scattered throughout the lung.

Mycobacterium tuberculosis (M. tuberculosis): The organism that causes TB and is sometimes called the tubercle bacillus; M. tuberculosis and three very closely related mycobacterial species (M. bovis, M. africanum, and M. microti) can cause tuberculous disease, and they compose what is known as the M. tuberculosis complex.

N

non-nucleoside reverse transcriptase inhibitors: a new class of drugs used to treat HIV infection.

nucleic acid amplification (NAA): A method for amplifying DNA or RNA that facilitates rapid detection of microorganisms.

nucleic acid probe (NAP): Nucleic acid probes provide a rapid method of species identification, specific for the genus Mycobacterium, the M. tuberculosis complex, M. avium, and M. intracellulare. Once the mycobacteria have been grown in culture, nucleic acid probes can identify the species in 2 to 8 hours.

P

polymerase chain reaction (PCR): A type of nucleic acid amplification test.

protease inhibitors: a new class of drugs used to treat HIV infection.

purified protein derivative (PPD): The type of tuberculin used in the Mantoux skin test.

pyrazinamide (PZA): A first-line drug used to treat TB disease, usually during the initial phase of treatment; should not be given to pregnant women.

pyridoxine (B₆): Supplement used with isoniazid chemotherapy to help prevent neuropathy.

R

rifabutin: a rifamycin drug similar to rifampin and used to treat TB in HIV-infected patients who are taking protease inhibitors

rifampin (RIF): A first-line drug used to treat TB disease; also used for preventive therapy in people with a positive skin test reaction who have been exposed to isoniazid-resistant TB. Rifampin has several possible side effects; i.e., hepatitis, turning body fluids orange and drug interactions).

S

serum glutamic-oxaloacetic transaminase (SGOT or AST): A measurement of liver function taken to assess hepatotoxicity.

streptomycin (SM): A first-line injectable drug used to treat TB disease; may cause hearing problems. Streptomycin should not be given to pregnant women.