IM3.15-22 | Pneumonia Treatment and Prevention — Summary & Reflection

KEY TAKEAWAYS

Empirical antibiotic selection (IM3.15): CAP outpatient (CURB-65 0–1): oral amoxicillin ± macrolide; COPD: add clavulanate; atypical: respiratory fluoroquinolone. CAP inpatient (CURB-65 2–3): IV ceftriaxone + IV azithromycin, or IV levofloxacin monotherapy. CAP severe/ICU (CURB-65 4–5): same + Pseudomonas cover if structural lung disease; + vancomycin/linezolid if MRSA. HAP/VAP late-onset: anti-pseudomonal beta-lactam + aminoglycoside ± vancomycin. Aspiration: IV co-amoxiclav or IV clindamycin + ceftriaxone.

Culture-directed therapy (IM3.16): Review at 48–72 hours; de-escalate to narrowest effective agent for confirmed pathogen; S. pneumoniae penicillin-sensitive → oral amoxicillin; MSSA → IV flucloxacillin; MRSA → vancomycin (trough 15–20) or linezolid. Set duration at prescription (5 days non-severe CAP; 7 days severe; 7–14 days HAP/VAP).

Hospitalisation (IM3.17): CURB-65 ≥3, or SpO2 <92%, bilateral infiltrates, hypotension, inability to self-manage at home, immunocompromised, comorbid decompensation.

Isolation (IM3.18): Airborne (N95 + negative pressure room): TB (suspected until 3 sputum smears negative), COVID-19, MERS. Droplet: influenza, Mycoplasma, pneumococcal (first 24 hours).

Supportive therapy and oxygen (IM3.19): Target SpO2 ≥94% (non-COPD); 88–92% (COPD). Escalate: nasal cannulae → face mask → Venturi → non-rebreather → HFNC → NIV (BiPAP for type 2 failure/COPD) → invasive ventilation.

Pneumococcal vaccine (IM3.21): PCV13 then PPV23 ≥8 weeks later for: age ≥65; COPD/asthma; heart failure; diabetes; CKD; liver disease; immunocompromised; asplenia.

Influenza vaccine (IM3.21): Annual for: age ≥65; chronic medical conditions (heart, lung, kidney, diabetes, liver); pregnant; healthcare workers; immunocompromised. Inactivated vaccine preferred; live attenuated is contraindicated in immunocompromised and pregnant women.

REFLECT

Return to the three patients in the opening hook. For the 72-year-old with CURB-65 4, you now know: start IV ceftriaxone + IV azithromycin immediately, collect blood cultures and sputum before the first dose, obtain ABG to assess for respiratory failure, target SpO2 ≥94% with HFNC if needed, communicate urgency to the family. For the 28-year-old with HIV and bilateral ground-glass infiltrates, you know: the standard CAP antibiotic will not cover PCP — add high-dose co-trimoxazole empirically and arrange urgent CD4 count and HIV confirmation; use HFNC for hypoxia. For the 55-year-old COPD patient asking about vaccines: he needs PCV13 today, PPV23 in 8 weeks, and the current influenza vaccine — and he needs to understand why, not just be told to 'come back for the jab.' The ability to apply these frameworks fluently — not as rules to recall but as clinical reasoning to apply — is what transforms a medical graduate into a clinician. How would you explain to a 72-year-old man with severe pneumonia, in two sentences, why he is being connected to a machine that breathes for him?