Pneumonia Flashcards
What is the pathological classification of pneumonia?
lobar vs bronchopneumonia
-
BRONCHOPNEUMONIA
- widespread patchy inflammation centred on airways
- often bilateral
- patchy areas of consolidation
- bronchi containing acute inflammatory exudate
- also upper lobe emphysema
-
LOBAR PNEUMONIA
- diffuse inflammation affecting an entire lobe/lobes
- photo - entire lobe, paler than other
- consolidation due to accum of acute inflammatory exudate within alveoli
- abrupt demarcation at interlobar fissure
This classification largely was based on macroscopic exam of lungs at autopsy in pts w/ florid pneumonias in a pre-antibiotic era. Problem - difficult to apply in most cases as patterns overlap + classical picture is extremely blurred by modern day abx therapy.
What does consolidation refer to?
- on CXR - refers to replacement of air in alveoli by fluid or other material, with preservation of underlying alveolar architecture
- in case of pneumonia, air is replaced by acute inflammatory exudate
- there is no destruction of underlying architecture
What are the typical organisms that cause community-acquired pneumonia?
- streptococcus pneumonia (pneumococcus) - most common bacterial cause, affects all ages particularly elderly. Also presents w/ herpes labialis + rusty sputum. Most common (60-75%). Lobar consolidation on CXR.
- haemophilus infulenzae - common cause of pneumonia in pre-existing lung disease: COPD. Can be diffuse or confined to one lobe.
The remainder of organisms causing CAP are a mixed bag termed ‘atypicals’ (an unhelpful term).
What are the ‘atypical’ organisms that cause CAP?
What organisms are responsible for hospital-acquired pneumonia (HAP)?
- E.coli (gram-negative)
- staphlococcus aureus
- pseudomonas
- klebsiella
- bacteroides
- clostridia
What organisms are responsible for pneumonia in the immunocompromised patient?
- bacteria: strep pneumoniae, staph aureus, pseudomonas
- fungi: pneumocystitis, candida albicans, aspergillus
- virus: influenza A virus, adenovirus, CMV, HSV, SARS, varicella
What are risk factors for pneumonia?
- underlying lung disease (COPD, bronchiectasis, obstruction)
- age (v young + v old)
- smoking
- alcohol xs
- winter months
- hospitalisation
- immunocompression
- IV drug use
- inhalation from oeseophageal obstruction
What are the symptoms of pneumonia?
- fever + rigors
- malaise
- anorexia
- dyspnoea
- cough + purulent sputum
- haemoptysis
- pleuritic chest pain
What are the signs of pneumonia?
- tachypnoea
- reduced chest expansion over affected area
- inc vocal resonance/tactile fremitus
- dull percussion note
- bronchial breathing
- coarse inspiratory crackles
- confusion
- cyanosis
- tachycardia
- hypotension
The severity of CAP is assessed based on the CURB-65 criteria.
What is the criteria?
- Confusion of new onset (AMT ≤8)
- Urea >7mmol/L
- Resp rate ≥30
- BP <90 systolic or ≤60 diastolic
- 65 years or
0-1 = home tx, 2 = hosp therapy, >3 = severe pneumonia (ITU)
What are clinical features that suggest an atypical organism is responsible?
- headache + flu-like symptoms
- dry cough
- extra-thoracic, systemic symptoms:
- abdo pain + diarrhoea (legionella)
- night sweats + weight loss (pneumocystitis or tb)
- discordance between chest signs and illness of pt
- NO leukocytosis
- sometimes no consolidation
What are the investigations for pneumonia?
- Bloods - FBC, U+E, LFT, CRP, cultures
- Urine (-> strep pneumoniae + legionella ag)
- Sputum
- CXR
- Oxygen saturation
- ABG
- Pleural fluid
- Bronchoscopy + bronchoalveolar lavage
What might a CXR show for pneumonia?
- lobar or multilobar consolidation
- cavitation
- pleural effusion
What is the management of CAP?
-
NON-SEVERE (CURB65 0-1)
- oral amoxicillin or clarithromycin or doxycycline
-
SEVERE (CURB65 2-5)
- benzylpenicillin IV
- clarithromycin IV
Oral switch to doxycycline or amoxicillin (+/- carithromycin PO)
What antibiotic should be used for legionella?
fluoroquinolone combined w/ clarithromycin or rifampicin
