Community-acquired pneumonia: severity assessment and antibiotics

Management— do this, in order

• Give appropriate empirical antibiotics as expeditiously as possible — mortality in hospitalised CAP correlates closely with their timely administration, and no test should delay the first dose: not a biomarker, not a sputum sample, not a radiograph.
• Titrate oxygen to SpO₂ 94–98%, or 88–92% in known or suspected chronic type 2 respiratory failure; in children there is no hypoxic-drive concern, so target 94–98% and never restrict oxygen in a hypoxic child.
• Outpatient, no comorbidity and no resistance risk: amoxicillin 1 g orally three times daily plus a macrolide (azithromycin 500 mg on day 1 then 250 mg daily for 4 days, or clarithromycin 500 mg twice daily) or doxycycline 100 mg orally twice daily; or doxycycline monotherapy; or macrolide monotherapy only where local pneumococcal macrolide resistance is under 25%.
• Outpatient with comorbidity (chronic heart, lung, liver or kidney disease, diabetes, alcohol excess, malignancy, asplenia) or resistance risk: amoxicillin–clavulanate 500/125 mg three times daily or 875/125 mg twice daily, or an oral cephalosporin (cefpodoxime 200 mg twice daily, cefuroxime 500 mg twice daily), plus a macrolide or doxycycline; or a respiratory fluoroquinolone alone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily, gemifloxacin 320 mg daily).
• Inpatient, non-severe, no risk factors: a β-lactam (ampicillin–sulbactam 1.5–3 g IV 6-hourly; ceftriaxone 1–2 g IV daily; cefotaxime 1–2 g IV 8-hourly; ceftaroline 600 mg IV 12-hourly; ertapenem 1 g IV daily) plus a macrolide (azithromycin 500 mg IV or orally daily, or clarithromycin 500 mg IV or orally twice daily), or a respiratory fluoroquinolone alone (levofloxacin 750 mg or moxifloxacin 400 mg IV or orally daily); if both are contraindicated, a β-lactam plus doxycycline 100 mg twice daily.Doctor / Nurse
• Inpatient, severe: a β-lactam alone is not adequate therapy — give a β-lactam (ceftriaxone 2 g IV daily in severe disease) plus a macrolide, or a β-lactam plus a respiratory fluoroquinolone, with observational data favouring the macrolide.Doctor / Nurse
• Add MRSA cover — vancomycin 15 mg/kg IV 12-hourly adjusted to renal function and serum levels, or linezolid 600 mg IV or orally 12-hourly — where MRSA has previously been isolated from the respiratory tract within the past year, or in severe disease with recent hospitalisation and antibiotics.Doctor / Nurse
• Add *Pseudomonas* cover — piperacillin–tazobactam 4.5 g IV 6-hourly, cefepime 2 g IV 8-hourly, ceftazidime 2 g IV 8-hourly, meropenem 1 g IV 8-hourly, imipenem 500 mg IV 6-hourly, or aztreonam 2 g IV 8-hourly in penicillin allergy — where *P. aeruginosa* has previously been isolated from the respiratory tract within the past year.Doctor / Nurse
• Supportive care: adequate hydration is a therapeutic measure, not comfort care, because dehydration suppresses sputum production; give balanced crystalloid to restore perfusion in shock, reassessing after each bolus, with vasopressors for fluid-unresponsive shock; and give thromboprophylaxis unless contraindicated.Doctor / Nurse
• Paracetamol 1 g orally or intravenously 6-hourly (maximum 4 g in 24 hours) matters more than it appears, because a patient splinting against pleuritic pain cannot cough or breathe deeply and will collapse a lower lobe.
• Paediatric antibiotics — weigh every child, never estimate: amoxicillin 45–90 mg/kg/day orally in doses 8 hours apart for non-severe pneumonia; ampicillin 200 mg/kg/day IV in doses 6 hours apart as first-line intravenous therapy in a previously well child; cefotaxime 75–225 mg/kg/day IV in doses 8 hours apart, or ceftriaxone 50–75 mg/kg/day IV 12–24 hourly, for severe illness or where resistance is a concern; benzylpenicillin 250,000–400,000 units/kg/day IV in divided doses 4–6 hours apart as an alternative first-line for pneumococcal disease.Doctor / Nurse
• More paediatric therapy: add vancomycin per local paediatric protocol in the critically ill child, including multilobar pneumonia with hypoxia or hypotension; use clindamycin or vancomycin as first-line alternatives in severe β-lactam hypersensitivity; and give erythromycin 50 mg/kg/day orally in four divided doses for 2 weeks for infant pneumonia due to *Chlamydia trachomatis*.Doctor / Nurse
• Treat for a minimum of 5 days and until clinical stability is achieved, switching to oral therapy when the patient can ingest and absorb the drug, is haemodynamically stable and is improving; hospital-acquired and ventilator-associated pneumonia are treated for 7 days, and anaerobic lung abscess requires a minimum of 3 weeks.
• Proven influenza warrants oseltamivir 75 mg orally or by nasogastric tube twice daily for 5 days in addition to antibacterials, with vigilance for MRSA superinfection.
• Sample a significant effusion in a septic patient for pH, glucose, protein, lactate dehydrogenase, Gram stain, culture, cytology and acid-fast bacilli — drainage is required if pH is below 7.2, glucose below 2.2 mmol/L or LDH above 1000 U/L, if bacteria are seen or cultured, or if the fluid is frank pus.DoctorNot available at your setup — Chest drain / tube thoracostomy.
• Offer an HIV test to every patient with pneumonia, since pneumonia is a common initial presenting illness in previously undiagnosed HIV infection.
• Reassess formally at about day 3, or sooner if deteriorating, working through five possibilities: is this pneumonia at all; is there a sequestered focus the antibiotic cannot reach (lung abscess or empyema); is the pathogen resistant or unexpected; is the drug, dose or frequency wrong and was it actually given; and is there a nosocomial superinfection.