Pneumonia Flashcards
How can pneumonia be classified?
- Anatomic distribution e.g bronchopneumonia/lobar pneumonia
- Etiology e.g primary/secondary
- Clinical setting e.g community acquired/healthcare associated
Describe lobar pneumonia
- Usually involves an entire lung - entire lobe affected
- Usually caused by Strep. pneumoniae
- Congestion, red and gray hepatization and resolution are present
- Opacification of entire lobe present on CXR
Describe bronchopneumonia.
- Patchy consolidation in lobe of lung
- Gravitation of secretions means can be bilateral basal in location
- Affects extremes of ages i.e infants and elderly
- CXR shows patchy opacification of lobe
Describe typical pneumonia
- Caused by extracellular organisms e.g bacteria
- Characterised by neutrophilic infiltration and presence of intra-alveolar exudates (causing consolidation)
- Acute onset of high graded fever and mucopurulent cough
- May be associated with pleuritic pain
Describe atypical pneumonia
- Caused by intracellular organisms e.g Chalmyida pneumoniae and viruses e.g rhinovirus and influenza
- Associated with lymphocytic infiltration and alveolar septal and interstitial inflammation
- Absence of alveolar exudates
- CLINICAL FEATURES - fever, dry cough, headache, myalgia
- PRODUCTIVE COUGH, PLEURAL INVOLVEMENT - UNCOMMON
Give examples of community acquired and hospital acquired infections.
- COMMUNITY - Strep, pneumoniae, Staph. aureus, Mycoplasma/Chlamydia pneumoniae
- HOSPITAL - E. coli, Pseudomonas, MRSA
What are some predisposing factors for lobar pneumonia?
Patients with the following
- Immunosuppression
- Neurological impairment of cough reflex
- Secretion retention
- Pulmonary oedema
- Impaired mucociliary clearance
- Respiratory tract infection (viral)
- Antibiotics/cytotoxics
- Tracheal instrumentation
- Impaired alveolar macrophages
- Other/Neoplasia
ACRONYM - INSPIRATION
Describe characteristics of lobar pneumonia.
- Common in adults (vagrants and alcoholics)
- Microorganisms gain entry to distal air spaces
- If treated promptly, recover
Describe the natural evolution of bacterial lobar pneumonia.
- RED HEPATISATION - Acute pneumonia
- GREY HEPATISATION - Sub-acute pneumonia
- RESOLUTION - Organising pneumonia
What are the pathological stages of lobar pneumonia? PART 1
- CONGESTION - outpouring of protein-rich exudate into alveoli
- RED HEPATISATION - accumulation of RBCs and polymorphs in alveolar spaces - appears like the alveoli
What are the pathological stages of lobar pneumonia? PART 2
- GREY HEPATISATION - accumulation of fibrin in lung spaces with red cell disintegration
- RESOLUTION - recover - lungs return to normal structure and function
What causes pleuritic chest pain in pneumonia?
- Pleurisy - inflammation of the pleura
- Pleura become red and inflamed
- Rub against one another when lungs expand to breathe in air
What causes dullness to percussion?
- Usually resonates due to presence of air
- Appears dull due to solid appearance of lung
What does C-reactive protein indicate?
- Activated during the immune response
- High CRP count indicates bacterial infection
When a patient is diagnosed with community-acquired pneumonia, what further tests might be sent to find out the cause of infection?
- SPUTUM - Gram stain and culture
- BLOOD - culture
- Nasal swabs - test for influenza and COVID
- Urine - test for legionella and pneumococcal antigens
What does pneumonia diagnosis in the hospital rely on?
- Symptoms and signs of acute lower respiratory tract infections
- Opacities on CXR not due to other causes
What are the key diagnostic factors for community-acquired pneumonia?
- Cough with increasing sputum production
- Dyspnoea
- Pleuritic chest pain
- Rigors/night sweats
What are some other diagnostic factors considered in community-acquired pneumonia?
- Myalgia
- Malaise
- Anorexia
- Lethargy
Describe the CURB-65 test.
- Higher CURB score, greater risk of mortality
- CONFUSION
- UREA > 7 mmol per litre
- Respiratory rate > 30
- BP - Systolic < 90 OR Diastolic < 60 mmHg
- Age > 65
What is the most common cause of community acquired pneumonia?
Strep. pneumoniae
What is bronchopneumonia characterised by?
- Patchy distribution affecting one or more lobes
- Inflammatory infiltrate extending from bronchioles into adjacent alveoli
What are the main characteristics of bronchopneumonia?
- Common in infancy and old age
- Pre-disposing conditions are debility and immobility
- Primary infection centred at bronchi can spread to adjacent alveoli
- Involvement of pleura - pleurisy common
What cases is bronchopneumonia particularly frequent in?
- Terminal event in chronic debilitating disease
- In infancy and old age
- Secondary infection to viral conditions
What are the pathological features of bronchopneumonia?
- Inflammation spreads from terminal bronchioles to related alveoli
- Lesions initially focal - involve one or more lobules
- Red to grey to bronchiole containing pus
Describe the macroscopic features of bronchopneumonia.
- Slightly elevated, dry, granular, grey-red to yellow areas with poorly defined margins
Describe the microscopic features of bronchopneumonia.
- Neutrophil-rich exudate filling bronchi, bronchioles and adjacent alveolar spaces
Name four types of acute pneumonias based on clinical setting.
- Community-acquired
- Hospital-acquired (nosocomial)
- Immunocompromised
- Aspiration
Describe nosocomial pneumonia. PART 1
- Pulmonary infections acquired in course of hospital stay
- Patients at risk - patients on ventilation, on immunosuppression, with severe underlying diseases and prolonged antibiotic regimens
Describe nosocomial pneumonia. PART 2
- Most common agents - Gram-negative rods e.g Pseudomonas, Enterobacteria and Staph. aureus
- Adverse impact on clinical course of ill patients and heightened cost of care
What are the risk factors for hospital acquired pneumonia?
- Advanced age
- Chronic underlying disease
- Immunosuppression
- Obesity and malnutrition
- Smoking, drug abuse and alcohol abuse
- Altered levels of consciousness
What are the risk factors for lobar pneumonia?
- Prolonged hospital/nursing home stay
- Chronic illness
- Prior antibiotic exposure
- Home infusion therpay/wound care
- Recent hospital admission
- Immunosuppression
- Haemodialysis
Describe what can cause pneumonia in immunocompromised hosts.
- Diseases such as AIDS
- Immunosuppressive drugs
- Therapeutic irradiation
- Opportunistic pathogens - bacteria e.g Pseudomonas aerguinosa, Legionella pneumophila, viruses e.g herpesvirus and fungi
- Splenectomy, chemotherapy-induced neutropenia and abnormal T-lymphocyte function
When does aspiration pneumonia occur?
- When fluid or food aspirated into lung
- Causes secondary inflammation and consolidation
Describe the characteristics of aspiration pneumonia. PART 1
- POPULATION AT RISK - debilitated patients or those aspirate gastric contents whilst unconscious or during repeated vomiting
- Can be caused chemically or bacterially
- Most common agents are anaerobic oral flora and aerobic bacteria
Describe the characteristics of aspiration pneumonia. PART 2
- Often necrotising
- Fulminant evolution
- COMPLICATIONS - Death and abscess formation
What are the complications of pneumonia? PART 1
- LUNG FIBROSIS - inflammatory exudate not fully absorbed - organised with residual fibrous scarring - causes lung dysfunction
- BACTERAEMIA - leading to septicaemia with meningitis, arthritis, enddocarditis
- LUNG ABSCESSES - single/multiple areas of suppuration
What are the complications of pneumonia? PART 2
- EMPYEMA - pus in pleural cavity due to extension of infection into pleural cavity
- PLEURAL EFFUSION
- DEATH
