Pneumonia

What is pneumonia according to the summary?

Pneumonia is a respiratory infection characterized by inflammation of the alveolar space and/or the interstitial tissue of the lungs. Summary 1

In industrialized nations, what is the significance of pneumonia as a cause of death?

Pneumonia is the leading infectious cause of death in industrialized nations. Summary 2

How is pneumonia most commonly transmitted?

Most commonly transmitted via aspiration of airborne pathogens (primarily bacteria, but also viruses and fungi). Summary 3

What factors help narrow down the likely pathogens causing pneumonia?

The most likely causal pathogens can be narrowed down based on patient age, immune status, and where the infection was acquired (community-acquired or hospital-acquired). Summary 4

How is pneumonia classified based on clinical features according to the summary?

Classified as either typical or atypical pneumonia based on clinical features. Summary 5

What are the typical clinical manifestations of typical pneumonia?

Sudden onset of malaise, fever, and a productive cough. Auscultation reveals crackles and bronchial breath sounds. Summary 6

What are the typical clinical manifestations of atypical pneumonia?

Gradual onset of unproductive cough, dyspnea, and extrapulmonary manifestations. Auscultation is usually unremarkable. Summary 7

What finding on chest x-ray confirms the diagnosis of pneumonia when accompanied by characteristic clinical features?

A newly developed pulmonary infiltrate on chest x-ray confirms the diagnosis. Summary 8

What is the general approach to managing pneumonia according to the summary?

Management consists of empiric antibiotic treatment and supportive measures (e.g., oxygen administration, antipyretics). Summary 9

What is the definition of respiratory failure?

The acute or chronic inability of the respiratory system to maintain adequate gas exchange. Definitions 10

How is hypoxemic respiratory failure defined based on arterial blood gas?

Defined as a PaO2 < 60 mm Hg (8 kPa). Definitions 11

How is hypercapnic respiratory failure defined based on arterial blood gas?

Defined as a PaCO2 > 50 mm Hg (6.5 kPa). Definitions 12

What is respiratory arrest?

The complete cessation of breathing in patients with a pulse. Definitions 13

What is respiratory distress?

A clinical syndrome associated with breathing disorders. Definitions 14

What is the most common bacterial pathogen causing community-acquired typical pneumonia?

Streptococcus pneumoniae is the most common cause. Etiology 15

Name two other common bacterial pathogens causing community-acquired typical pneumonia besides S. pneumoniae.

Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, or Staphylococcus aureus. (Any 2) Etiology 16

What bacterial pathogen is the most common cause of community-acquired atypical pneumonia in the ambulatory setting?

Mycoplasma pneumoniae. Etiology 17

Name two other bacterial causes of community-acquired atypical pneumonia besides Mycoplasma.

Chlamydia pneumoniae, Chlamydia psittaci, Legionella pneumophila, Coxiella burnetii, or Francisella tularensis. (Any 2) Etiology 18

Name two common viral causes of community-acquired pneumonia.

Respiratory Syncytial Virus (RSV), Influenza viruses, Parainfluenza viruses, CMV, Adenovirus, or Coronaviridae (e.g., SARS-CoV-2). (Any 2) Etiology 19

Name two common pathogens causing hospital-acquired pneumonia (HAP).

Gram-negative pathogens (Pseudomonas aeruginosa, Enterobacteriaceae, Acinetobacter spp.), Staphylococci (S. aureus), or Streptococcus pneumoniae. (Any 2) Etiology 20

What does the mnemonic "Atypically, Legions of Clams Mind their P's and Q's!" help recall regarding pneumonia pathogens?

Helps recall bacterial causes of atypical pneumonia: Legionella, Chlamydia (pneumoniae/psittaci), Mycoplasma, Psittacosis, Q fever (Coxiella). Etiology 21

What pathogen typically causes lobar pneumonia?

Most commonly Streptococcus pneumoniae. Less commonly Legionella, Klebsiella, H. influenzae. Etiology 22

Name two pathogens commonly causing bronchopneumonia.

S. pneumoniae, S. aureus, H. influenzae, or Klebsiella. (Any 2) Etiology 23

What types of pathogens typically cause interstitial pneumonia?

Atypical pathogens (Mycoplasma, Chlamydia, Legionella, Coxiella) or viruses (RSV, CMV, influenza, adenovirus). Etiology 24

What are common pathogens causing pneumonia in immunocompromised patients?

Encapsulated bacteria, Pneumocystis jirovecii, Aspergillus fumigatus, Histoplasma capsulatum, Coccidioides immitis, Candida species, CMV, S. aureus, Gram-negative bacteria. Etiology 25

What are common pathogens causing pneumonia in newborns?

Escherichia coli, Streptococcus agalactiae (Group B strep), Streptococcus pneumoniae, or Haemophilus influenzae. Etiology 26

What are common pathogens causing pneumonia in children (4 weeks - 18 years)?

C. trachomatis (infants), C. pneumoniae, S. pneumoniae, RSV, or Mycoplasma. Etiology 27

What are common pathogens causing pneumonia in young adults (18-40 years)?

Mycoplasma, Influenza virus, C. pneumoniae, or S. pneumoniae. Etiology 28

What are common pathogens causing pneumonia in adults (40-65 years)?

S. pneumoniae, H. influenzae, Mycoplasma, anaerobes, or viruses. Etiology 29

What are common pathogens causing pneumonia in elderly individuals?

S. pneumoniae, H. influenzae, Gram-negative bacteria, anaerobes, or Influenza virus. Etiology 30

List three major risk factors for developing pneumonia.

Old age, immobility, chronic diseases (cardiopulmonary), airway abnormalities (bronchiectasis, CF), immunosuppression (HIV, DM, meds), alcoholism, impaired airway protection (stroke, sedation), smoking. (Any 3) Etiology 31

What type of pneumonia should be considered in patients with altered mental status or risk factors for aspiration?

Consider aspiration pneumonia. Etiology 32

How is pneumonia classified based on location acquired?

Community-acquired pneumonia (CAP), Hospital-acquired pneumonia (HAP), or Ventilator-associated pneumonia (VAP). (Healthcare-associated pneumonia - HCAP - is no longer used). Classification 33

How is pneumonia classified based on clinical features?

Typical pneumonia (classic symptoms, often lobar/bronchopneumonia) or Atypical pneumonia (indolent course, extrapulmonary symptoms, often interstitial). Classification 34

How is pneumonia classified based on the area of the lung affected?

Lobar pneumonia (one lobe), Bronchopneumonia (around bronchi/bronchioles), Interstitial pneumonia (between alveoli), or Cryptogenic organizing pneumonia (noninfectious). Classification 35

What is the most common route of infection for pneumonia pathogens?

Microaspiration (droplet infection) of airborne pathogens or oropharyngeal secretions. Pathophysiology 36

How does pneumonia impair gas exchange?

Infiltration/inflammation → impaired alveolar ventilation → V/Q mismatch with intrapulmonary shunting → hypoxia (increased A-a gradient). Pathophysiology 37

What is the characteristic pathological feature of lobar pneumonia?

Inflammatory intra-alveolar exudate resulting in consolidation of an entire lobe (or segment). Pathophysiology 38

Describe the "red hepatization" stage of lobar pneumonia (days 3-4).

Macroscopic: red-brown, dry, firm, liver-like consolidation. Microscopic: Alveoli filled with exudate rich in fibrin, bacteria, erythrocytes, and inflammatory cells; thickened alveolar walls. Pathophysiology 39

Describe the "gray hepatization" stage of lobar pneumonia (days 5-7).

Macroscopic: uniformly gray, liver-like consistency. Microscopic: Alveoli filled with suppurative exudate (neutrophils, macrophages); erythrocytes/bacteria degraded; thickened walls. Pathophysiology 40

What characterizes bronchopneumonia pathologically?

Acute inflammatory infiltrates filling the bronchioles and adjacent alveoli, typically in a patchy distribution, often involving lower lobes or RML. Pathophysiology 41

What characterizes interstitial pneumonia pathologically?

Diffuse patchy inflammation primarily involving the alveolar interstitial cells. Pathophysiology 42

What are the characteristic symptoms of typical pneumonia?

Sudden onset of severe malaise, high fever, chills, and productive cough with purulent sputum. Clinical 43

What are characteristic auscultation findings in typical pneumonia?

Crackles and bronchial breath sounds over the affected area. Clinical 44

What are characteristic percussion and palpation findings in typical pneumonia?

Dullness on percussion and enhanced tactile fremitus over the affected area. Clinical 45

What are characteristic symptoms of atypical pneumonia?

Gradual onset, nonproductive dry cough, dyspnea, and often extrapulmonary symptoms (fatigue, headache, sore throat, myalgias). Clinical 46

What are typical auscultation findings in atypical pneumonia?

Auscultation is often unremarkable. Clinical 47

What is the diagnostic basis for pneumonia according to general principles?

Diagnosis is based on new pulmonary infiltrates on chest imaging in patients with respiratory symptoms and systemic inflammatory response. Diagnosis 48

What laboratory finding strongly suggests a bacterial cause for lower respiratory tract infection?

Elevated serum procalcitonin (PCT) levels (≥ 0.25 mcg/L correlate with increased probability). Diagnosis 49

When are microbiological studies (blood/sputum cultures, urinary antigens) indicated for severe Community-Acquired Pneumonia (CAP)?

Indicated for ALL patients with severe CAP. Diagnosis 50

When are microbiological studies indicated for nonsevere Community-Acquired Pneumonia (CAP)?

Specific tests (Influenza, COVID, Legionella antigen) based on exposure/transmission. Sputum culture if prior hospitalization/IV Abx, MRSA/Pseudomonas risk, or structural lung disease. Diagnosis 51

What imaging modality is indicated for all patients suspected of having pneumonia?

Chest x-ray (posteroanterior and lateral views). Diagnosis 52

What is the characteristic chest x-ray finding in lobar pneumonia?

Opacity (consolidation) of one or more pulmonary lobes, potentially with air bronchograms. Diagnosis 53

What is the characteristic chest x-ray finding in bronchopneumonia?

Poorly defined patchy infiltrates scattered throughout the lungs, potentially with air bronchograms. Diagnosis 54

What is the characteristic chest x-ray finding in atypical/interstitial pneumonia?

Diffuse reticular opacity, often with absent or minimal consolidation. Diagnosis 55

When is Chest CT indicated for evaluating pneumonia?

For inconclusive chest x-ray, recurrent pneumonia, poor response to treatment, or suspected complications (empyema, abscess). Diagnosis 56

What scoring system helps determine the need for hospitalization in Community-Acquired Pneumonia (CAP)?

The CURB-65 score or the Pneumonia Severity Index (PSI/PORT score). Disposition 57

What do the letters in the CURB-65 score stand for?

Confusion, Urea (>7 mmol/L or BUN >20 mg/dL), Respiratory rate (≥30/min), Blood pressure (SBP ≤90 or DBP ≤60 mmHg), Age (≥65 years). Disposition 58

What CURB-65 score generally indicates a need for hospitalization?

CURB-65 score ≥ 2 generally indicates hospitalization is needed. (Score ≥ 3 suggests ICU). Disposition 59

What empiric antibiotic is recommended first-line for outpatient CAP in previously healthy patients without risk factors?

Monotherapy with Amoxicillin OR Doxycycline OR a Macrolide (if resistance <25%). Treatment 60

What empiric antibiotic approach is recommended for outpatient CAP in patients with comorbidities/risk factors?

Combination therapy (Antipneumococcal β-lactam + Macrolide/Doxycycline) OR Respiratory Fluoroquinolone monotherapy. Treatment 61

What empiric antibiotic approach is recommended for inpatient, nonsevere CAP?

Combination therapy (Antipneumococcal β-lactam + Macrolide/Doxycycline) OR Respiratory Fluoroquinolone monotherapy. Treatment 62

What empiric antibiotic approach is recommended for inpatient, severe CAP (ICU treatment)?

Combination therapy (Antipneumococcal β-lactam + Macrolide OR Respiratory Fluoroquinolone). (Alternative: Aztreonam + Fluoroquinolone for penicillin allergy). Treatment 63

If Pseudomonas risk factors are present in severe CAP, what antibiotic class must be included in the regimen?

An antipneumococcal, antipseudomonal β-lactam (e.g., piperacillin-tazobactam, cefepime, ceftazidime, meropenem, imipenem). Treatment 64

If MRSA risk factors are present (or nasal swab positive) in severe CAP, what antibiotic should be added?

Add Vancomycin OR Linezolid. Treatment 65

What is the empiric antibiotic approach for Hospital-Acquired Pneumonia (HAP) in patients without high mortality/MRSA risk?

Monotherapy with an antipneumococcal, antipseudomonal β-lactam OR Levofloxacin. Treatment 66

What empiric antibiotic approach is recommended for HAP patients with MRSA risk factors (but not high mortality risk)?

Combination therapy: Agent with MRSA activity (Vancomycin/Linezolid) PLUS an antipseudomonal agent (β-lactam or fluoroquinolone or aztreonam). Treatment 67

What empiric antibiotic approach is recommended for HAP patients at high risk for mortality or with structural lung disease?

Triple therapy: Agent with MRSA activity PLUS TWO different antipseudomonal agents (e.g., β-lactam + fluoroquinolone/aminoglycoside/aztreonam; avoid two β-lactams). Treatment 68

What is the typical duration of antibiotic treatment for HAP/VAP?

Seven days of therapy are usually sufficient. Treatment 69

What pathogen is a common cause of atypical pneumonia outbreaks in schools, colleges, or military facilities?

Mycoplasma pneumoniae. Pathogen-Specific 70

What extrapulmonary finding can be associated with Mycoplasma pneumoniae infection?

Generalized papular rash or Erythema multiforme. Elevated cold agglutinin titers may also be seen. Pathogen-Specific 71

What antibiotic classes are effective against Mycoplasma pneumoniae?

Macrolides, Doxycycline, or Fluoroquinolones. (Beta-lactams are ineffective). Pathogen-Specific 72

What is aspiration pneumonia?

Pneumonia occurring as a result of oropharyngeal secretions and/or gastric contents aspiration into the respiratory tract. Aspiration PNA 73

What is aspiration pneumonitis?

Chemical pneumonitis caused by aspiration of gastric acid, initially causing tracheobronchitis. Aspiration PNA 74

List two major risk factors for aspiration (leading to aspiration pneumonia/pneumonitis).

Altered consciousness (alcohol, sedation, stroke), apoplexy/neurodegenerative conditions, GERD/esophageal disorders, NG feeding tube use. (Any 2) Aspiration PNA 75

How do the immediate symptoms typically differ between aspiration pneumonitis and aspiration pneumonia?

Pneumonitis: Immediate bronchospasm, dyspnea, wheezing/crackles. Pneumonia: Often no immediate symptoms. Aspiration PNA 76

What lung segments are most commonly affected by aspiration when in the supine position?

Superior segment of the right lower lobe and posterior segment of the right upper lobe. Aspiration PNA 77

Does aspiration pneumonitis typically require antibiotic therapy?

No, aspiration pneumonitis typically requires supportive care only and self-resolves within 24-48 hours. Aspiration PNA 78

How does pregnancy affect the risk and management of community-acquired pneumonia (CAP)?

Physiological changes may increase risk of severe course. Chest x-ray is not contraindicated. Low threshold for admission. Use pregnancy-safe antibiotics (avoid certain macrolides, FQs, tetracyclines). CAP in Pregnancy 79

What is a common complication involving the pleura in pneumonia?

Parapneumonic pleural effusion. Complications 80

What serious infection involves pus accumulating in the pleural space, often secondary to pneumonia?

Pleural empyema. Complications 81

List two severe pulmonary or systemic complications of pneumonia.

Lung abscess, ARDS, respiratory failure, or sepsis. (Any 2) Complications 82

How does the CURB-65 score correlate with mortality risk in pneumonia?

Score 0: ~1% risk; Score 1-2: ~10% risk; Score 3: ~14% risk; Score 4: ~40% risk. Prognosis 83

List two key preventative measures against pneumonia.

Immunization (Pneumococcal, Influenza, COVID-19), smoking cessation, or prevention of ventilator-associated infections. (Any 2) Prevention 84