Tuberculosis and Its Treatment

These flashcards cover the key concepts related to tuberculosis, its transmission, treatment phases, and the medications used in its management.

Granuloma

A small, organized collection of immune cells that forms in infected tissues, primarily in the lungs, as the body's defensive response to contain and prevent the spread of Mycobacterium tuberculosis bacteria.

Latent TB infection

A stage where a person has Mycobacterium tuberculosis bacteria present in their body but does not exhibit symptoms of active tuberculosis, is not infectious, and has a normal chest X-ray. Individuals with latent TB are often treated to prevent progression to active disease.

Pulmonary TB

The most common form of active tuberculosis, occurring when Mycobacterium tuberculosis bacteria escape from a granuloma and actively multiply, leading to inflammation and destruction of lung tissue. It is characterized by symptoms such as persistent cough, fever, night sweats, and weight loss, and is infectious.

Isoniazid (INH)

A potent bactericidal medication and a cornerstone of tuberculosis treatment, effective against actively growing Mycobacterium tuberculosis. It is used for both latent TB treatment and as part of a multi-drug regimen for active TB.

• Adverse Reactions: Can cause peripheral neuropathy (nerve damage leading to numbness/tingling in hands/feet, especially in malnourished, alcoholic, or diabetic patients; often preventable with concomitant pyridoxine (Vitamin B6)), hepatotoxicity (liver injury causing elevated LFTs, fatigue, dark urine, jaundice), rash, and gastrointestinal upset.

• Toxicities: Severe, potentially fatal, hepatotoxicity.

• Tests to be Ordered: Baseline and periodic liver function tests (LFTs) including AST, ALT, and bilirubin. Monitor for symptoms of peripheral neuropathy and vision changes.

• Contraindications: Acute liver disease, history of previous isoniazid-associated liver injury.

Extrapulmonary TB

Active tuberculosis disease that occurs when Mycobacterium tuberculosis bacteria spread beyond the lungs to other parts of the body, such as the lymph nodes, pleura, bones, joints, kidneys, central nervous system, or gastrointestinal tract. Symptoms vary depending on the affected organ.

First line medications for TB

The initial and most effective antimicrobial agents used in combination to treat active tuberculosis. These typically include Isoniazid (INH), Rifampin (RIF), Ethambutol (EMB), and Pyrazinamide (PZA), chosen for their synergistic activity and ability to minimize resistance.

Side effects of Ethambutol (EMB)

The primary adverse reaction is optic neuritis (dose-dependent inflammation of the optic nerve, leading to decreased visual acuity, red-green color blindness, and possible visual field defects, which is often reversible upon drug discontinuation). Other side effects may include dermatitis, hyperuricemia (which can precipitate gout), and general GI reactions like nausea or abdominal pain.

• Toxicities: Ocular toxicity (optic neuritis).

• Tests to be Ordered: Baseline and monthly visual acuity tests, red-green color discrimination tests, and ophthalmoscopic examinations.

• Contraindications: Pre-existing optic neuritis, or in patients unable to report visual changes (e.g., young children, unconscious individuals).

Direct Observational Therapy (DOT)

A critical public health strategy for tuberculosis treatment adherence, where healthcare workers directly observe patients taking their prescribed tuberculosis medications. This ensures proper dosing, promotes completion of therapy, and helps prevent drug resistance.

Pyrazinamide (PZA)

A bactericidal medication primarily used in the intensive initial phase of active TB treatment due to its unique activity in acidic environments, such as within macrophages and inflammatory lesions.

• Adverse Reactions: Can cause hepatotoxicity (liver injury characterized by elevated LFTs, fatigue, jaundice), hyperuricemia (elevated uric acid levels, often leading to acute gouty arthritis or arthralgia), rash, and gastrointestinal upset.

• Toxicities: Significant hepatotoxicity and hyperuricemia.

• Tests to be Ordered: Baseline and periodic liver function tests (LFTs) and serum uric acid levels.

• Contraindications: Acute gout, severe hepatic impairment.

Jaundice

A medical sign characterized by yellow discoloration of the skin, mucous membranes, and whites of the eyes (sclera), caused by elevated bilirubin levels in the blood. It is a key indicator of liver dysfunction or damage, such as hepatotoxicity, which can be an adverse reaction to anti-tuberculosis medications like Isoniazid and Pyrazinamide.

Peripheral neuropathy

Damage to the peripheral nerves, typically resulting in numbness, tingling, burning pain, or weakness, most commonly in the hands and feet. It is a significant adverse reaction to Isoniazid, which interferes with pyridoxine (Vitamin B6) metabolism, and can often be prevented or mitigated by co-administration of pyridoxine.

Bactericidal

Referring to medications or substances that directly kill bacteria, rather than merely inhibiting their growth. Bactericidal drugs, such as Isoniazid and Pyrazinamide, are crucial for rapidly reducing bacterial load and achieving cure in active tuberculosis infections.

Acute gout

A painful form of inflammatory arthritis caused by the deposition of uric acid crystals in the joints, leading to sudden, severe attacks of pain, swelling, redness, and tenderness. It is a contraindication for the use of Pyrazinamide, as this medication can elevate uric acid levels (hyperuricemia) and worsen or precipitate gout attacks.