Pneumonia Flashcards
What is the definition of pneumonia?
Pneumonia = infection of the lung parenchyma by bacteria, fungi, viruses characterised by exudation into the alveoli.
Case Definition: Lower respiratory tract signs with radiological evidence of consolidation
If no radiological evidence of consolidation 🡪 this is diagnosed as LRTI instead
What are LRTI signs?
- Cough
- Fever
- Breathless +/- Wheeze
How do you differentiate between bronchopneumonia vs lobar pneumonia?
Bronchopneumonia = Characterized by patchy foci of consolidation (pus in many alveoli and adjacent air passages) scattered in one or more lobes of one or both lungs
Lobar pneumonia = Characterized by an acute inflammation of the entire lobe or lung. Histologically, tissue changes are classified into four stages: congestion, red hepatization, grey hepatization and resolution
What are the 4 phases of progression of lobar pneumonia?
1) Congestion Day 1- 2
- Pulmonary vessels dilate, exudate enters alveoli
- Patient is febrile, develops dyspnoea and cough
2) Red hepatisation Day 2-4
- Alveoli fills with RBCs and fibrin strands 🡪 lobe of lung is solid
- No gas exchange 🡪 Patient is hypoxic, breathless; may cough up blood stained sputum (due to RBC that fills alveoli)
3) Grey hepatisation Day 4-8
- Alveoli full of neutrophils and dense fibrous strands 🡪 Lung remains solid
- Patient coughs up purulent sputum; remains breathless
4) Resolution Day 8-10
- Monocytes clear the inflammatory debris; normal lung architecture restored
How do you decide if a patient has pneumonia (IFLASH)?
Infiltrate* - consolidation on CXR: this is the single most definitive sign of pneumonia
Fever
Leucocytosis
Auscultatory findings
- Coarse crepitation
- Decreased air entry
- Bronchial breath sounds
Sputum
- Pneumonia usually p/w productive cough
- Atypical pneumonia may be non-productive
- Colour of sputum have no definite correlation
Hypoxemia
What are the symptoms of pneumonia?
- Cough – painful, dry, productive, haemoptysis
- Sputum and colour
- Fever and rigors (shivers)
- Dyspnoea
- Fever – swinging fever suggests empyema
- Pleuritic chest pain
- Anorexia
- Sudden onset malaise
What is the physical examination findings of pneumonia?
- Vitals -> pyrexia, tachypnoea, tachycardia, hypotension, desaturation
- Mental status -> confused
- Respiratory
- Consolidation -> decreased chest expansion, dullness to percussion, bronchial breath sounds, increased vocal resonance
- Signs of respiratory distress, cyanosis (if severe)
When do you decide to admit a patient with pneumonia?
CURB 65
- Confusion of new onset (AMTS ≤8 – abbreviated mental test score)
- Urea ≥7
- Respiratory rate ≥30/min
- Blood pressure: systole ≤90mmHg and/or diastole ≤60mmHg
- Age ≥65
Score 2= admit to ward
Score >2= admit to ward, may need ICU
What are the pathogens responsible for community acquired pneumonia?
Typicals: Strep Pneumo; Moraxella Cattarhalis, Haemophilus Influenzae
Atypicals (Walking Pneumonia): Legionella; Chlamydophila, Mycoplasma
What is hospital acquired pneumonia and what are the pathogens responsible for it?
Think: MRSA, Pseudomonas
Pneumonia that develops ≥48h after admission to hospital
CXR on admission must be clear
What is healthcare associated pneumonia?
- Develops within 3 months of having been in a healthcare setting for which pt has been hospitalized for 2 or more days
- Nursing home or long-term care facility (common)
- Hospital or haemodialysis clinic
What is VAP and what are the pathogens responsible for it?
Think: MRSA, Pseudomonas
48-72 hours after endotracheal intubation
What is aspiration pneumonia normally caused by and what are the PMH associated with it?
Think: Klebsiella, anaerobes and gram negatives
Pts w/ stroke, myasthenia, bulbar palsies, ↓ consciousness, oesophageal disease etc
What are the pathogens more likely causing pneumonia in a patient post URTI?
Influenza, Staph Aureus (but rare)
What are the pathogens more likely causing pneumonia in a diabetic patient?
Melioidosis & Klebsiella
What is the pathogen most likely causing pneumonia in an immunocompromised patient with soil exposure patient? What are the antibiotics used to treat?
Melioidosis
Drug of choice – Ceftazidime
Empirical Abx – ABC: Azithromycin, (Benzyl) Penicillin, Ceftazidim
What are the pathogens more likely causing pneumonia in a HIV patient?
- CD4>200: S. pneumoniae, H. influenza, TB
- CD4<200: S. pneumoniae, H. influenza, TB, PCP, Cryptococcus, Histoplasma
What pathogens cause cavitatory lesions on cxr?
- Staph A, Klebsiella, TB
- However, TB has less dyspnoea, more constitutional symptoms of weight loss, night sweats, fever + chronic cough >2 weeks
What pathogen is likely to cause pneumonia in a patient with antibiotic exposure?
Pseudomonas
What pathogen is likely to cause pneumonia in a patient with bats exposure?
histoplasma (spelunking)
What pathogen is likely to cause pneumonia in a patient with birds exposure?
chlamyhophilia psittaci (psittacosis)
What pathogen is likely to cause pneumonia in a patient with cats parturient exposure?
coxiella burnetti (Q fever)
What pathogen is likely to cause pneumonia in a patient with rabbits exposure?
Fransicella Tularensis (Tularaemia)
What are the CXR findings in a patient with pneumonia?
Classically: Looking for heterogenous opacification of the lung field w/ air bronchograms
- Restricted to 1 lobe if lobar; or diffuse if atypical
- However, requires adequate hydration for consolidation to appear on CXR
Other possible findings
- Cavitatory lesions w/ air fluid level
- Parapneumonic effusion w/ blunting of costophrenic angles
- Lung Collapse
What are the investigations (other than CXR) to conduct in a patient with pneumonia?
Sputum culture, Gram-stain, AFB Smear
Urine Antigen Test
- Strep pneumoniae and Legionella (only possible thru urine Ag)
- Advantages over culture: faster; not affected by antibiotics
Influenza nasopharyngeal swab PCR – if viral is suspected
Blood cultures – before starting antibiotics
FBC (check leucocytosis)
- Typical pneumonia: WBC > 15 x 109/L, ESR >100mm/hr, CRP >10mg/L
- No Leucocytosis in Atypical Pneumonia
CRP, ESR, Procalcitonin (sign of bacterial sepsis / severe bacterial infection)
ABG if SpO2 <92%
ECG – for QTc prolongation
Renal Panel (UECr)
- To assess hydration levels and electrolyte derangement
- ↑ Urea is a marker of severity (CURB-65)
- Legionella: hyponatremia, renal failure
LFT
- Baseline LFTs: antibiotics can cause cholestatic picture
- Legionella: deranged LFTs, hepatitis
Bronchioalveolar lavage – if no sputum production and a Dx is mandatory (eg: ICU pt)
What antibiotics to treat a patient with CAP (Home/ general ward setting)
Augmentin & Clarithromycin (Klacid)
- Augmentin to cover for typicals; Clarithromycin to cover to atypicals
If penicillin allergy 🡪 switch to quinolones (Levofloxacin, Moxifloxacin).
- Ciprofloxacin has bad lung penetration.
- Alternatively: Lincosamide
If QTc prolongation 🡪 switch to doxycycline
However, at primary care we tend to give single-agent – Augmentin or amoxicillin
What antibiotics to treat a patient with severe Pneumonia (requiring ICU) + Signs of Melioidosis / with RFs?
Have to also cover melioidosis 🡪 esp for DM and Immunocompromised patients
Triple antibiotics (ABC) – Azithromycin + (Benzyl) penicillin + ceftazidime
Switch to Ceftazidime once Dx of Melioidosis is established
What antibiotics to treat a patient with HCAP/ VAP?
Piperacillin- tazobactam (Piptazo) + Vancomycin
- Vanco to cover MRSA; Piptazo to cover Pseudomonas
- Note: Other Anti-Pseudomonal agents include Ceftazidime, Meropenem, Ciprofloxacin
How long is the antibiotic treatment for pneumonia?
CAP (Home/General/ICU) – 5-7 days
Melioidosis/MRSA/Bacteremia – total duration 1 month
Other than antibiotics, how else is pneumonia managed?
1) Oxygen – maintain SpO2 between 94% and 98% (in COPD maintain between 88% and 92%)
2) IV fluids – hypotensive patient with volume depletion
3) Thromboprophylaxis – if admitted >12h, give subcutaneous LMWH, TED stockings
4) Nutritional supplementation
5) Analgesia – paracetamol, NSAIDs
6) Pneumococcal vaccinations for >65 years and previously unvaccinated
What is the parapneumonic effusion? What are the investigations done for it?
Parapneumonic effusion = pleural effusion that develops adjacent to bacterial pneumonia
CXR: to pick up parapneumonic effusion
Thoracocentesis: aspiration of pleural fluid under USS guidance
1) Indicated if
- >10mm on CXR (significant enough volume)
- Loculated
- Thickened parietal pleura (empyema)
2) Sample sent for Gram-stain, culture, fluid protein, glucose, LDH
3) Light’s criteria to assess if exudative or transudative
- pleural fluid/ serum protein ratio >0.5
- pleural fluid/ serum LDH ratio >0.5
- LDH > 2/3 ULN of normal serum LDH
USS – to assess for loculations, guides thoracocentesis
What are the findings in uncomplicated parapneumonic effusion? How is it managed?
- Exudative effusion w/ neutrophilic influx
- -ve culture, pH >7.2, glucose >3.3, w exudative changes (LDH and protein)
- Has no inherent infection / inflamm, will resolve if pneumonia
Management
- Observation; No need to treat / drain as Abx treatment of pneumonia is sufficient
- Serial chest X-ray or U/S to assess improvement
What are the findings in complicated parapneumonic effusion? How is it managed?
- Bacterial invasion of pleural space
- Also Exudative effusion w/ neutrophilic influx
- +ve culture, pH <7.2, glucose <3.3
- In this stage, pleural fluid has been infected 🡪 triggers inflammation & fibrin deposition -> pleural becomes thickened and +/- loculated
Management
- Empiric IV antibiotics (will be part of treatment of pneumonia); Coverage – anaerobes: e.g. co-amoxiclav
- Tube thoracostomy -> drain effusion as it is unlikely to resolve spontaneously -> if no loculations
- Consider VATS (video-assisted thoracoscopic surgery) with debridement if -> if Cx by multiple loculations, thickened pleura
- If empyema, 4-6 weeks of antibiotics may be needed
What are the findings in thoracic empyema? What are the causative agents>
- Bacterial invasion of pleural space
- +ve culture, pH <7.2, glucose <3.3
- pus in the pleural space: yellow, cloudy, foul odour
- Early indications of empyema: ongoing (Swinging) fevers, rising or persistently high inflammatory markers despite antibiotics
Commonly implicated micro-organisms
- Streptococcus spp (50%) – most common cause of parapneumonic effusion
- Anaerobes (20%)
- S.aureus (10%)
- Gram negative aerobes (10%)
What are the causes of lung abscess?
- Aspiration pneumonia: hx of excessive alcohol consumption, impaired swallowing
- TB
- Pneumonia caused by Staphylococcus aureus (post-URTI) or Klebsiella pneumonia
- Septic emboli containing Staphylococci – multiple lung abscesses. If multiple lung abscesses in IVDA, investigate for infective endocarditis of tricuspid valves. Infarcted areas of lung can cavitate and become infected
- Spread from amoebic liver abscess – usually right lower lobe following trans-diaphragmatic spread
- Bronchial obstruction by endoluminal cancer
- Foreign body inhalation
What are the clinical feature of lung abscess?
- Swinging fever
- Cough
- Purulent, foul-smelling sputum
- Pleuritic chest pain
- Haemoptysis
- Malaise
- Weight loss
- Clubbing
What are the complications of lung abscess?
Massive haemoptysis (especially when cavitation lies on pulmonary vessels)
What is the management of lung abscess?
- Surgical Treatment
- Long term Abx Therapy
