LRTI and Pneumonia Flashcards
(31 cards)
What is pneuomnia?
General term denoting inflammation of the the lung parenchyma due to infection
What is pneumonitis?
Inflammation of the lung due to non-infective causes e.g. physcial damage or chemical damage
What is the common feature of pnemonias?
A cellular exudate in the alveolar spaces
What common microbiota exist in the respiratory tract?
- Viridans streptococci
- Neisseria species
- Anaerobic candida species
Why aren’t the lungs sterile?
- Have normal alveolar microbiota
- Aspirate microbiomes from the URT
- Microbiomes spread from blood stream
- Direct spread of bacteria
What defences does the respiratory tract have to prevent infection?
- Muco-ciliary clearance mechanisms: nasal hair, ciliated epithelium
- Cough and sneezing reflex
- Respiratory immune system from lymphoid follicles of the pharynx and tonsils
- Alveolar macrophages
- Secretory IgA and IgG
- Alveolar microbiota prevent other organisms attaching and growing
What happens to the lungs in the course of a typical infection?
- Alveolar macrophages fail to stop pathogen
- Cytokines recruit more macrophages
- Inflammation causes increased permability
- More WBC/ proteins recruited to aid macrophages
What happens outside the lungs in a typical respiratory tract infection?
- Inflammatory mediators (cytokines and chemokines) released into systemic circulation
- Activates bones marrow to produce more neutrophils
- Cardiac output increased to deliver more blood to the lungs
- Raised body temperature to fight infection
What host factors make it harder to deal with a respiratory tract infection?
- Age >65
- Lifestyle: smoking, alcohol, drugs
- Chornic lung diseases
- Aspiration
- Immunocompromised
- Metabolic problems
- Co-infection with other viruses
What kind of drugs can pre-dispose to respiratory tract infections?
- Antacids (PPI/ H2 antagonists)
- Antiphyschotics
- ACE inhibitors
- Glucocorticoids
What symptoms do you get with a upper resiratory tract infection?
- Rhinitis
- Pharyngitis
- Epiglottis
- Laryngitis
- Sinusitis
- Trachetitis
- Otitis media
What is the difference between chronic and acute bronchitis
Acute bronchitis - usually and infective cause that causes inflammation of the medium sized airways
- CXR normal
- Can be managed with bronchodilation and antibiotics
Chronic bronchitis - is not due to an infective cause
What is the main way to classify pneumonias? Give the main categories
Classified based on the source of infection
- Community Aquired
- Hospital Aquired
- Aspiration Pneumonia
- Pneumonia in the immunocompromised patient
What is the difference between lobar pneumonia and bronchpneumonia?
Lobar = affects 1 lobe of the lung
Bronchopneumonia = patchier infection
What can you see microscopically in pneumonia?
- exudate- fibrin rich fluid
- neutrophil infiltration
- macrophage infiltration
What is the most common caustative organisms in community aquired pneumonia?
Streptococcus Pneumonia (most common)
What other organisms can cause community aquired pneumonia?
- Haemophillus influenzae
- Moraxella Catarrahalis
- Klebsiella Pneumonia
- Staphylociccus aureus
Which ‘atypical’ organisms can cause community aquired pneumonia?
- Mycoplasma pneumoniae (most common)
- Chlamydia pneumoniae
- Legionella Pneumonphila
How do you diagnose community aquired pneumonia?
Clinical findings: Cough (+/- sputum), dyspnoea, pleurisy, fever, tachycardia, crackles
Imaging: must see changes on CXR consolidations, inflitrates, cavitations
How do you define hospital aquired pneumonia?
Infection of lower respiratory tract in hospitalised patients occuring >48 hours afer admission
What are the causative organisms of hospital aquired pneumonia?
- Gram Negative bacteria
- Staphylococcus Aureus (including MRSA)
How do you assess the severity of pneumonia?
CURB 65
- Confusion
- Urea >7 mmol/L
- Resp Rate >30
- Blood Pressure <90 Systolic, <60 diastolic
- >65 years old
Score of 2-5 managed as severe
What investigations would you do if you suspected pneumonia?
- FBC
- U&Es
- CRP
- Arterial Blood Gas
- CXR
What microbiological investigations would you order for suspected pneumonia?
- sputum test
- blood culture
- broncho alveolar lavage fluid (BAL)
- Nose and throat swabs
- Urine (testing for legionella/ pneumococcus)
- Serum antibodies
