TB Flashcards
What is the pathogen that causes TB?
MycobacteriumTuberculosis
What is the leading killer of HIV pts?
TB
What is a major characteristic about m. tuberculosis?
Acid-fast bacilli (AFB)
How is TB spread and acquired?
- Spread from infected person to susceptible host
2. Infection with M. tuberculosis with inadequate containment by immune system
How are TB infections presented in the lungs?
- Initial infection may be contained and walled off leading to the formation of granulomatous inflammation
- Initial infections that are not contained
A. May cause either local disease (primary progressive pulmonary tuberculosis)
B. May disseminate hematogenously to seed other organs such as kidney, CNS, or bones
What is the pathophys of TB?
- Person inhales airborne droplet nuclei containing viable organism
- Tubercle bacilli that reach alveoli are ingested by alevolar macrophages
If not contained, replicate
Attract inflammatory cells
Form tubercle
Spread hematogenously
Seed other parts of body (eye, skin, kidney)
Most become suppressed by immune system at this point
No symptoms develop
Form caseating granulomas
Bacilli can survive in granulomas for years to decades (primary TB)
What is primary TB?
Initial infection, (+) tuberculin skin test (PPD test)
Usually self limiting
5-10% develop TB over lifetime
What is Progressive Primary or Active TB?
(+) PPD
Early progression of infection
Clinically ill
What is Latent TB?
No active disease
TB bacteria in lungs but body prevents infection from developing- not contagious or infectious
(+) PPD, asymptomatic, (-) CXR, (-) sputum Cx
Can have reactivation of disease if host immune system is compromised- latent TB active TB
What are the sxs of TB?
Cough (chronic) > 3 weeks Dry to productive Fatigue, malaise Anorexia, wt loss Fever Night sweats \+/- Hemoptysis Patient appears chronically ill & malnourished
(Sx’s progress slowly)
What are the dx studies for TB?
1. Sputum culture for AFB A.May take up to 12 weeks to grow B. AFB smear takes several hours 2. Nucleic acid amplification (NAA) test for M tuberculosis 3. CXR A. Cavitations B.Infiltrates C. Apical segment involvement 4. Needle biopsy of pleura A. Caseating granulomas hallmark
What is the criteria for a PPD reaction for ppl with HIV or repeated contact with active TB?
> 5mm
When is a PPD reaction os >10mm with evidence of TB on CXR considered a positive reaction?
Recent immigrants from TB prevalent country
Mycobacteria lab personnel
Diabetics or others with immunocompromised health status
When is a PPD reaction >15mm considered positive?
Patients with no risk for TB
How latent TB treated?
- INH x 9 months daily (Vit B 6 to ↓ neuropathy) OR
- Rifampin x 4 months daily
