Mod 9 Tuberculosis Flashcards
What is the most common association/definition of Tuberculosis?
TB is a chronic infectious disease caused by nonmotile, nonspore, forming bacteria belonging to the family Myocobacteriaceae (M.Turberculosis).
- M. TB is the most important agent in any human agent of disease
- primarily affects the lungs but can invade any part of the body
Why is Mycobacteriacaeae an important agent of TB?
Time required to produce a new gen of bacteria is fast (x18-24h)
- Can exist in both aerobic and anaerobic environments
- Can survive within granuloma, macrophage, and cytoplasm
How does Tuberculosis spread (TB) spread?
Air droplets via cough, sneeze, or speaking (airborne pathogen)
- close contacts are at highest risk of infection (>8h or intense contact)
What lung fields are usually the most affected by Tuberculosis (TB)?
- What size of Tuberculosis (TB) can reach the alveoli
- what factors affect size of droplets?
1-5 um can affect the right middle/lower lobe
- droplet sizes > 5cm are trapped by mucosa and removed by cilia
- Humidity, Temp, ventilation affect droplet size
What happens to patients who contract Tuberculosis (TB) but remain unaffected?
TB remains dormant -> latent TB infection (LTBI)
- bc body can’t get rid of it
- few cases of infection directly progress to pulmonary disease
What population groups are most affected by Tuberculosis (TB)?
- Children < 4 yrs
- Immunocompromised
Is the initial stage of infection for Tuberculosis (TB) fast or slow?
They multiply Slow (2-12 wks)
- cell division q25-35hrs
What role do granulomas have with Tuberculosis (TB) and why is it important to pay attention to?
Granulomas develop around the bacteria to limit bacteria multiplication to other sites
- Granulomas = clusters of WBC
- Granulomas secrete pro and anti inflammatory cytokines
- This phase establishes latency of the infection
What usually develops in immunocompromised hosts with Tuberculosis (TB)?
Fibrosis and calcifications occur due to primary progressive TB
When is primary Tuberculosis (TB)/active TB usually experienced?
The first 2 years following infection
- Dormant bacteria may persist before reactivated following a temporary or permanent immune depression
What are the 3 categories of Tuberculosis (TB)?
- Primary TB aka primary infection stage
- Latent TB aka post/dormant TB
- Disseminated TB aka extrapulmonary/Miliary/TB-disseminated
What is Tuberculosis (TB) often mistaken for?
Pneumonia
- Inflammatory response is
- Symptoms can be mild-severe
- Conincides w/a positive tuberculin reaction
What are initials lesions that encapsulate Tuberculosis (TB) called?
Ghon nodules
What is the immune response to Tuberculosis (TB)?
Similar to pneumonia
- Immune system responds to infected area by producing protective cell walls called granulomas or tubercle
- Granuloma encapsulate TB halting spread of infection
- Body begins healing process
- Fibrotic and calcified tissue replace granuloma
What is Caseous necrosis?
Dead cells that are not completly digested since they’re trapped within a granuloma
What does a Granuloma consist of
Central core with caseous necrosis and TB bacilli
Why are Fibrotic and calcified tissue replacement a problem following a granuloma?
Can cause the Parenchyma to retract and scar leading to a restrictive component
- if too close to bronchi, could cause a bronchiectasis to occur
What are the clinical manifestations of Primary Tuberculosis?
- TB can occur w/o clinical signs and symptoms
- Or resemble mild resp tract infection i.e pneumonia
What can the infection caused by primary Tuberculosis (TB) progress to?
- Pleural Effusions
- Fever and Cough
- Pain
- Dyspnea
What locations of the lung fields are affected by Secondary Tuberculosis (TB)?
- When does it reactivate?
Secondary TB is contagious and reactivates from mycobacterial LTBI.
- located where O2 concentrations are the highest
- Apices are primarily affected, in some cases the base depending on position
What are the most frequently detected signs/manifestations of Secondary Tuberculosis (TB) or LTBI?
- Low grade fever
- Asthenia (physical weakness/lack of energy)
- Anorexia
- Night sweats
- Mucopurulent cough last > 2-3 wks
- Hemoptysis
- Pleuritic chest pain