tuberculosis

Mycobacterium

-does not gram stain

-rod shaped bacilli, nonmotile, no spores, no capsule, cord formation

-complex, waxy, layered

-aerobic, slow growth

-acid fast staining: red, fluorescent

TB etiology

-mycobacterium tuberculosis

-acid fast bacilli, aerobic, slow growing

-mycolic acid

-ziehl-neelsen staining

TB pathophysiology

-airborne droplet nuclei

-passed from people with active pulmonary TB

active TB

-caused by mycobacterium

-actively replicating and causing disease

-sx: cough, fever, weigh loss, fatigue

-contagious

latent TB

-bacteria are present but not causing illness

-TB present but not causing issues

-no sx

-NOT contagious

primary TB

-initial infection

-patho: inhaled > deposition in alveoli > forms Ghon focus> spread to hilar lymph nodes via drainage > go away(5%), latent infection(90%), or primary disease(5%)

secondary TB

-when infection becomes active again after period of being latent

-patho: in previously infected > reactivates or new infection > cavitation (abnormal thick wall, air filled space), fibrosis, local spread

TB risk factors

-HIV/AIDS

-healthcare workers

-homeless

-incarcerated

-foreign born/ endemic areas

-native american

-DM

-CKD

-immunosuppression

-cancer

TB pulmonary sx

-fever, night sweats, weight loss, fatigue

-chronic dry cough >3 weeks

-hemoptysis (cough blood)

-chest pain

-dyspnea

-lymphadenitis, joint pain, headache, dysuria, hematuria, abdominal pain

TB dx

1. tuberculin skin test (TST/PPD/mantoux)

-positive = >5 HIV+ recent contact/immunocomp, >10 high risk, >15 low risk

-according to diameter of induration

2. interferon-gamma release assay (IGRA): more specific, BCG vaccine

-1. confirmatory: CXR

-primary= hilar lymphadenopathy, lower/mid lobe

-reactivation= upper lobe, cavitation

-2. confirmatory: sputum study= ABF smear, culture(gold standard), PCR

-3. confirmatory: tissue biopsy= caseating granulomas (necrotizing)

Rifampin

-MOA: bind to bacterial RNA polymerase > inhibit RNA synthesis

-SE: turn all body fluids orange, hepatitis, flu syndrome

-strong CYP inducer

-empty stomach

-hepatotoxicity

Isoniazid

-MOA: inhibits mycolic acid synthesis by KatG

-SE: peripheral neuropathy > reversible vit B, hepatitis

Pyrazinamide

-MOA: inhibits cell membrane metabolism > accumulation of toxins in mycobacterial cell

-caution in pregnancy

-SE: hyperuricemia, hepatotoxicity

ethambutol

-MOA: inhibit mycobacterium arabinosyl transferase II > disrupt mycobacterial cell wall

-SE: optic neuritis: red and green color loss

active TB tx

-RIPE therapy for 2 months

-reduce to isoniazid and rifampin for 4 months

-isolation for 2-4 weeks

latent TB tx

only choose one method

1. isoniazid 9 months

2. rifampin 4 months

3. isoniazid + rifapentine 3 months

pregnancy TB tx

-active: RIP for 9 months, monitor LFT, vit B6 supplement

-latent: isoniazid for 9 months, vit B6 supplement