Pneumonia

Question 1

define pneumonia?

(+ clinical definition?)

Answer 1

inflammation of lung parenchyma distal to the terminal bronchioles, which includes the respiratory bronchioles, alveolar ducts, and alveoli

LRTI Sx
+ focal Sx (crackles), systemic Sx (fever) OR {unexplained CXR shadowing}

Question 2

what is a chest infection?

Answer 2

• non-specific term for LRTIs
• tends to be used for milder presentations – i.e. acute bronchitis – rather than pneumonia
• acute bronchitis +/- productive cough and fever, but no focal chest signs and CXR is clear
• unlike pneumonia, Abx not routinely indicated

Question 3

common causes CAP?

ordered from most to least likely

Answer 3

• BACTERIA

• Strep. pneumoniae (50)
• H. influenzae (7)
• Staph. aureus (2)
• Moraxella catarrhalis (2)

• ‘ATYPICALS’:

• Chlamydophila pneumoniae (10)
• Mycoplasma pneumoniae (5-15)
• Legionella pneumophila (3)

• VIRAL:

• COVID :(
• influenza A+B
• RSV

• IMMUNO↓:

• Pneumocystis jirovecii (Pneumocystis pneumonia, PCP)
• CMV

Question 4

definition and causes of HAP?

Answer 4

• develops >48h post-admission
• pathogens similar to CAP in the first 4 days
• later
- Gram -ve enterobacteria (Klebsiella, E. coli)
- Staph. aureus (inc. MRSA)
- Legionella
- Pseudomonas

Question 5

causes aspiration pneumonia? bugs?

Answer 5

• NM (stroke, myasthenia gravis)
• ↓consciousness (anaesthesia, alcohol intoxication)

• similar to HAP

• Klebsiella in alcoholism
• anaerobes like Peptostreptococcus, Fusobacterium, and Prevotella

Commonly affects right lower lobe**

Question 6

causes and clinical picture of atypical pneumonia?

Answer 6

• either bugs that aren’t common, or bugs that can’t be gram stained (Mycoplasma, Chlamydophila)
• generally “walking well” (mild clinical picture, but mostly in M+C)
• also caused by Legionella from stagnant water, and that can be nasty

Question 7

Sx + Ex to expect in pneumonia?

Answer 7

• SOB
• cough with purulent sputum +/- possibly blood
• pleuritic pain
• fever, malaise
• cyanosis, confusion
• ↑RR, ↑HR, AF
• consolidation leads to dull percussion
• ↑vocal resonance (VR)
• bronchial breathing (i.e. ↑breath sounds, BS)
• **both pneumonia and effusion cause dull percussion, but pneumonia is noisy (↑VR, ↑BS) while effusion goes shhh (↓VR, ↓BS).

Question 8

what may cause a lobar pneumonia with rusty sputum, 10 percent have oral herpes?

Answer 8

Strep. pneumo

Question 9

cause more common in COPD patients?

Answer 9

H. influenzae and Moraxella

Question 10

cause if it may be bilateral, and can occur post-influenza?

Answer 10

S. aureus

Question 11

persistent dry cough, mild fever, malaise, headache, and myalgia, but usually self-resolves over weeks?

(peaks in 4-yearly epidemics)

immunological complications include erythema multiforme and haemolytic anaemia

Answer 11

Mycoplasma pneumo (atypical)

Question 12

gradual onset, initial pharyngitis/URTI symptoms, and headache. Usually self-resolves, but may take months?

Answer 12

Chlamydophila pneumo (atypical)

Question 13

flu-like prodrome followed by cough (dry then productive or bloody), SOB, + D,V. Bilateral in severe cases?

Answer 13

Legionella

“Pontiac fever” is infection without lung involvement

Question 14

dry cough, bilateral pneumonia, desaturation on exertion, HIV+?

Answer 14

PCP

Question 15

“currant jelly sputum”?

Answer 15

Klebsiella

Question 16

acquired from sheep and other farm animals. Part of Q fever, which includes flu-like symptoms, hepatitis, and endocarditis?

Answer 16

Coxiella burnetii

Question 17

acquired from birds. Causes fever, dry cough, headache, splenomegaly, and arthritis?

Answer 17

Chlamydophila psittaci

“P”igeon = “P”sittaci

Question 18

Ix pneumonia?

Answer 18

• CURB-65 to score severity. 1 for each of:

• Confusion: abbreviated mental test ≤8 or disoriented
• Urea >7 (in the community, this is optional, use CRB-65 instead)
• RR ≥30
• BP: SBP <90 or DBP ≤60
• Age ≥65

0-1 is mild
2 may require hospitalisation
≥3 is severe and may require ITU

Question 19

How to Ix/Tx a mild CAP in the community?

Answer 19

• 70 percent of patients with mild CAP are managed in the community
• they require few, if any, Ix beyond obs
• if the diagnosis is unclear, get a CRP
• **Diagnose pneumonia and give Abx if CRP >100 mg/L. Consider diagnosis if CRP 20-100.

Question 20

inpatient Ix of pneumonia?

Answer 20

BEDSIDE
• O2 sats. ABG if <92% or severely unwell
• ECG if tachy
• Sputum culture
• Strep. pneumo and Legionella urine antigen tests. 75 percent sensitive

BLOODS
• FBC
• U+E (Legionella ↑urea and ↑creatinine, ↓Na+ due to SIADH) (Mycoplasma: ↓Na+)
• LFT (↑LFTs commoner in Legionella)
• CRP (↑↑CRP suggests Strep. pneumo)
• blood culture
• Mycoplasma - +ve cold agglutinin test

IMAGING
• CXR (also arrange follow up CXR 6 weeks later to check if clear and rule out underlying lung disease)
• High-res CT for PCP may show ground glass opacities

Question 21

Tx CAP?

Answer 21

• Mild-moderate: amoxicillin PO

• Clarithromycin or doxycycline if allergic
• Clarithromycin if atypical suspected (monotherapy if mild, added to amoxicillin if moderate)

• Severe: co-amoxiclav, cefuroxime, or cefotaxime IV (or levofloxacin if allergic), plus clarithromycin IV

• If hospitalised, start within 4 hours
• Monitor response to treatment with CRP

Question 22

Tx HAP?

Answer 22

• piperacillin/tazobactam, 3rd generation cephalosporin, meropenem, or levofloxacin IV
• Co-amoxiclav is a PO alternative or stepdown
• Add vancomycin or teicoplanin or linezolid if MRSA suspected

Question 23

Tx aspiration pneumonia?

Answer 23

• clindamycin, levofloxacin, or piperacillin/tazobactam

Question 24

Tx PCP?

Answer 24

• co-trimoxazole

* add steroids if moderate or severe: prednisolone PO or hydrocortisone IV

Question 25

general Tx of pneumonia?

Answer 25

* 5 days Abx (longer if remains febrile or unstable, or for certain pathogens) * if starting IV, review after 48 hours for possible PO stepdown * O2 * Fluids * Paracetamol

Question 26

complications of pneumonia?

Answer 26

* fever should resolve within 1 week * cough and SOB may take up to 6 weeks to resolve, and fatigue may persist up to 3 months * respiratory failure * sepsis and septic shock * uncomplicated parapneumonic pleural effusion, empyema (purulent, colonized pleural effusion) * lung abscess

Question 27

pathophysiology of lung abscess?

Answer 27

* necrotic tissue leaves pus-filled cavity | * may follow pneumonia, aspiration, or lung tissue damage (infarct, tumour, trauma)

Question 28

Sx of lung abscess?

Answer 28

* non-specific respiratory and systemic symptoms * dullness to percussion * clubbing

Question 29

Ix lung abscess?

Answer 29

* Blood and sputum cultures * Bloods: FBC, U+E, LFT, CRP * CXR shows cavitation with fluid level * Consider CT * Culture fluid from abscess via bronchoscopy or trans-thoracic aspiration

Question 30

Tx lung abscess?

Answer 30

* 8 weeks antibiotics, initially IV for 2-3 weeks * chest physio to help drain it * 10 percent will require CT-guided or open drainage