Pneumonia Flashcards
Basic definition of pneumonia
Infection of the lung parenchyma
Community acquired pneumonia (CAP):
- stats on death
- risk factors (8)
- pattern of infection
- CAP/influenza is the 6th most common form of death
- Risk factors:
- -> age >65 years
- -> asthma
- -> immunosuppression
- -> COPD
- -> CHD
- -> smoking
- -> drinking
- -> cerebrovascular disease
- seasonal pattern - influenza pneumonia; also bacterial pneumonia is secondary to influenza
Pneumonia pathogenesis
- 3 ways of acquiring infection
- change in lungs
1) contiguous
2) from oral pharyngeal cavity (aspiration)
3) hematogenous pneumonia
- pus cells enter alveoli from capillaries, result in purulent/suppurative inflammation; consolidation of lungs
Clinical presentation
- on presentation (6)
- on examination (3)
- lab work-up
On presentation:
- sputum, cough, shortness of breath, fever, chills, pleuritic chest pain,
On examination:
- tachycardia, tachypnea, evidence of consolidation
Lab work-up:
- leukocytosis (white blood cells in blood)
Diagnosis
- what do you need?
- clinical diagnosis requires 2 things. Caveat?
- microbiological diagnosis (what to do? - 3 things)
- Chest X-ray (clinical symptoms and history are not specific enough)
1) Both evidence of new pulmonary infiltrate compatible with pneumonia
2) clinical symptoms of pneumonia - -> BUT! Chest infiltrates on X-ray can also be due to other things (RBCs, cancer, etc)
Microbiological diagnosis:
- -> difficult (only 50% of pneumonia cases identify specific pathogens)
- sputum sample (for gram stain and culture and sensitivity)
- nasopharyngeal sample
- 2 blood culture sets
ETIOLOGY of CAP!!!
- Typical (40-60%)
a) Streptococcus pneumoniae (15-25%)
b) haemophilus influenzae (2-10%)
c) moraxella catharralis (0-5%) - Atypical (10-30%)
a) mycoplasma pneumoniae (1-10%)
b) chlamydophilia pneumoniae (5-15%)
c) Legionella pneumophilia (0-15%) - Other pathogens (5-25%)
a) Viral agents (2-15%)
b) pneumocystis jirovecii (0-10%)
c) mycobacterium tuberculosis (0-10%) - Unknown etiology (30-60%)
Streptococcus pneumoniae
- feature of culture (2)
- haemolysis?
- morphology (detailed)? gram-stain? cellular respiration?
1) little dips in centre of culture (virulent factor)
2) greening
- alpha-haemolytic
- gram-positive diplococci (lancet shaped), aerobic
Etiology and risk factors (4)
- bronchiectasis
- influenza season
- aspiration
- 4th one
1) bronchiectasis = pseudomonas aeruginosa
2) staphylococcus aureus
3) oral anaerobes
4) animal exposure
Difference between CAP and hospital acquired pneumonia (HAP)
HAP are:
- more likely to be gram-negative (enterobacteriaceae
or pseudomonas aeruginosa), and more likely to be staphylococcus aureus
CRB-65 score
- 4 features
- point system?
- how does treatment differ?
1) age >65
2) respiratory rate >30 per minute
3) confusion
4) blood pressure: sbp <90 mmHg; dbp <60 mmHg
One point for each feature
0 points: treated at home
- -> treat with antibiotics that covers “typical” etiology of pneumonia
- -> amoxicillin-clavulanic acid
1-2 points: admit to hospital
- -> treat with antibiotics that cover both “typical” and “atypical”
- -> amoxicillin-clavulanic acid and azithromycin
3-4 points: ICU or step-up/step-down ward
–> cefotaxime and azithromycin
Prevention (4)
1) smoking
2) drinking
3) influenza vaccination
4) pneumococcal vaccination (for s. pneumoniae)
QUIZ:
You are seeing a 70-year-old otherwise well patient with left lower lobe pneumonia. You do not have a microbiologic diagnosis.
What is the most likely etiologic agent?
Streptococcus pneumonia
