8. Lower Respiratory Tract Infection And Pneumonia Flashcards
What are the common microbiota of the respiratory tract?
Viridans streptococci, neisseria spp., anaerobes candida sp
What are some less common microbiota of the respiratory tract?
Streptococcus pneumoniae, streptococcus pyogenes, haemophilus influenzae
What are the defences of the respiratory tract?
- Muco-ciliary clearance mechanisms: nasal hairs, ciliated columnar epithelium
- Cough and sneezing reflex
- Respiratory mucosal immune system: lymphoid follicles of the pharynx and tonsils, alveolar macrophages, secretory IgA and IgG
- Alveolar microbiota
What is the course of a typical infection in the lungs?
- Alveolar macrophage fails to stop pathogen
- Cytokines to recruit more macrophages
- Inflammation leads to increased permeability
- More WBC/proteins to aid macrophages
What causes dysregulation?
Pathogen
Host factors
Drugs
What are some host factors?
Age >65 Smoking, alcohol, drugs Chronic lung diseases Aspiration Immunocompromised Metabolic - malnutrition, hypoxamia, acidosis Co-infection with virus
What are some common upper respiratory tract infections?
Rhinitis (cold) Pharyngitis Epiglottitis Laryngitis Tracheitis Sinusitis Otitis media
What are some lower respiratory tract infections?
Bronchitis Pneumonia Bronchioles is Bronchiectasis Empyema Lung abscess
What is acute bronchitis?
Inflammation of medium sized airways
What are the symptoms of acute bronchitis?
Cough Fever Increased sputum production Increased SOB CXR normal
What organisms can cause acute bronchitis?
S. pneumoniae
H. influenzae
M. catarrhalis
What is the treatment for acute bronchitis?
Bronchodilation
Physiotherapy
Antibiotics if bacterial
What are some common lower respiratory tract infections?
Community acquired pneumonia
Hospital acquired pneumonia
Ventilated acquired pneumonia
What is the pathology in pneumonia?
Acute inflammatory response
Exudation of fibrin-rich fluid
Neutrophil infiltration
Macrophage infiltration
What are the typical organisms that cause most CAP?
Strep. pneumoniae Haemophillus influenzae Moraxella catarrhalis Staph aureus and MRSA Klebsiella pneumonia Group A streptococcus pyogenes
What are some of the atypical organisms that cause pneumonia?
Mycoplasma
Legionella - contaminated water
Chlamydophila pneumoniae
Chlamydophila psittaci - exposure to birds
What are the clinical findings in CAP/
Cough Dyspnoea Pleurisy Fever Tachycardia Organ dysfunction Crackles
What is present on imaging in CAP?
Consolidations
Infiltrates
Cavitations
How do you assess severity of CAP?
CURB-65 - confusion, urea >7, respiratory rate >30, BP <90 and <60, >65 years
Score 2 maybe admit
Score 2-5 manage as severe
What investigations should be done in CAP?
FBC U and E C reactive protein Arterial blood gases CXR
What are the microbiological investigations done in CAP?
Sputum Blood untrue Broncho alveolar lavage fluid Nose and throat swabs Urine Serum
How do you manage CAP?
Mild - treat empirically
Moderate - investigations (blood cultures, sputum, urinary streptococcal antigen)
Severe - moderate + bronchoscopic specimens
What are the differential diagnoses for CAP?
Heart failure and pulmonary oedema PE Atelectasis Aspiration Drug reactions Lung cancer Interstitial lung disease
What is the treatment for CAP?
Antibiotics - 5-7 days for mild, 7-10 for severe
Mild-moderate: amoxicillin or doxycycline or erythromycin
Moderate-severe: needing admission, co-amoxiclav and clarithromycin/doxycycline
What are some complications of pneumonia?
Empyema, lung abscess, bacteraemia
What is the aetiology of HAP?
Staphylococcus aureus MRSA Enterobacteriaciae Pseudomonas spp Fungi (candida sp)
What is the first line and second line treatment for HAP?
First line: co-amoxiclav
Second line/ITU: piperacillin/tazobactam or meropenem
What is aspiration pneumonia?
Aspiration of exogenous material or endogenous secretions into respiratory tract
Common in patients with neurological dysphagia, epilepsy, alcoholics, drowning
How do you treat aspiration pneumonia?
Mild - no treatment
Moderate to severe - co-amoxiclav
How can you prevent pneumonia?
Immunisation - flu vaccine, pneumococcal vaccine
Chemoprophylaxis - oral penicillin/erythromycin
Smoking advice
