Pneumonia. Flashcards
What are the most common causative organisms of CAP in order of highest to lowest?
Streptococcus pneumoniae 70% Atypicals/viruses Haemophilus influenza Staphylococcus aureus. Other bacteria.
What is streptococcus pneumoniae?
Gram positive cocci in pairs or short chains.
It is alpha haemolytic on culture.
Has a draughtsman appearance.
What is the treatment for streptococcus pneumoniae?
Penicillin sensitive e.g. Amoxicillin.
What antibiotic can we use for staph aureus?
Coamoxiclav but not amoxicillin.
What are some predisposing factors to nosocomial pneumonia?
Intubation, ICU, antibiotics, surgery and immunosuppression.
What organisms most commonly cause nosocomial pneumonia?
60% are gram negative organisms.
Includes: pseudomonas aeriginosa and coliforms such as E.coli and Klebsiella sp.
When do we admit people with pneumonia to the hospital?
Signs of sepsis, low sats or respiratory failure.
What does pneumonia mean?
Disease of the lungs.
What is the pathophysiology of pneumonia?
Infection involving the distal airspaces usually with inflammatory exudation. Fluid filled spaces lead to consolidation.
Are the lungs sterile under normal circumstances?
No they contain commensal bacteria.
How do we classify pneumonia?
By clinical setting, by organism and by morphology.
What viruses can commonly cause pneumonia?
Influenza, parainfluenza, measles, varicella-zoster, respiratory syncytial virus (RSV).
Who does CAP classically affect?
Otherwise healthy young adults in close proximity e.g. Barracks or dormitories.
What 4 general patterns does CAP manifest as?
Lobar, bronchopneumonia, interstitial pneumonia and miliary pneumonia.
What is lobar pneumonia and what normally causes it?
Confluent consolidation involving a complete lung lobe.
Usually caused by streptococcus pneumoniae (pneumococcus)
Can be other organisms e.g. Klebsiella and legionella.
What is the pathology of pneumonia?
Classic acute inflammatory response with exudate and immune system involvement.
What does the classical inflammatory response cause in pneumonia?
E.g. Exudate contents.
Exudation of fibrin rich fluid
Neutrophil infiltration
Macrophage infiltration
Resolution.
What are the complications of pneumonia?
Organisation with fibrous scarring.
Abcess.
Bronchiectasis
Empyema.
What is bronchopneumonia?
Infection starting in the airways and spreading to adjacent alveolar tissue . Most often seen in pre-existing disease.
What are some secondary causes of pneumonia?
COPD, CF, complications of viral infection and as a result of aspiration.
What organisms are usually seen in aspiration pneumonia?
Staph, anaerobes and coliforms.
What is the definition of CAP?
Infection of the alveoli, distal airways and interstitium of the lungs that occurs outwith the hospital setting.
What are parenchyma?
The functional parts of the organ of the body.
What is stroma?
Structural tissues e.g. Connective tissue.
What is the annual incidence of CAP in the UK?
About 5-11 per thousand.
What causal agent of CAP are less frequent in the elderly?
Mycoplasma and legionella infections.
What are risk factors for CAP?
Winter months, being very young of very old. Chronic lung, heart, renal and liver disease. DM and immunosuppression.
How is CAP usually contracted? I.e what methods of transmission.
Acquired via inhalation into lung segment or lobe.
Less commonly from secondary bacteraemia from a secondary source such as E.coli urinary tract infection.
Can also be CAP from aspiration.
What is the only form of CAP involving multiple pathogens?
Aspiration CAP.
What are independent risk factors for CAP?
Alcoholism, asthma, immunosuppression, institutionalisation and age over 70.
How does alcohol use affect pneumonia? What is alcoholism an independent risk factor for in respiratory disease?
Higher incidence of gram neg bacterial pneumonia. Worse clinical symptoms. Require longer courses of antibiotics. Prolonged, fever, slower resolution and higher rates of empyema.
Excessive alcohol use is an independent risk factor for the development of acute respiratory distress syndrome.
What is ALPS and what is its mortality rate?
Alcoholism
Leukopenia.
Pneumococcal sepsis
Moratality rate of 80%
What do oral steroids do in relation to infection?
Increase infection risk as it knocks off the B cell numbers.