Community-acquired pneumonia
Score the severity with CURB-65 and oxygen levels, give the right antibiotic within 4 hours (1 hour if septic), and think of TB when it does not settle.
A 71-year-old man has had a cough with rusty sputum and fever for three days, and today he is muddled. RR 32, BP 96/58, SpO₂ 89% on air. Urea 54 mg/dL (9 mmol/L). The X-ray shows right lower lobe consolidation.
How sick is he, and which antibiotic?
- Oxygen to targetSpO₂ 94–98% (88–92% if CO₂ retainer).
- Check for sepsisIf septic, follow the Sepsis Six: antibiotics within 1 hour.
- Chest X-rayConfirms the diagnosis and shows effusion or cavity.
- Score the severityCURB-65, plus oxygen level and other illnesses.
- Cultures before antibioticsBlood cultures and sputum. Never delay antibiotics to get them.
- Antibiotics by severityWithin 4 hours of diagnosis (1 hour if septic).
- Fluids if dry or low BP500 mL boluses with reassessment.
- Think TBIf symptoms for weeks, weight loss, night sweats, or upper lobe cavities.
- Systolic BP below 90 or lactate above 2 mmol/L
- SpO₂ below 92% on air or RR 30 or more
- New confusion
- CURB-65 of 3 or more
- Effusion with continuing fever
- Not improving after 48–72 hours
- Sepsis and septic shock
- Respiratory failure
- Empyema
- Tuberculosis
- Legionella or other atypical infection
- PE or heart failure presenting as "pneumonia"
| CURB-65 0–1 | Low severity. Usually home with oral antibiotics |
| CURB-65 2 | Moderate. Usually admit |
| CURB-65 3–5 | High severity. Admit, senior review, consider HDU |
| Timing | Antibiotics within 4 hours, within 1 hour if septic |
| Duration | 5 days for most, review at day 3 |
Check every dose against a current drug reference and your hospital protocol.
On this page
What pneumonia is
Pneumonia is an infection of the lung tissue itself, where the air sacs fill with pus and fluid. On examination and X-ray this shows as consolidation. The common bacterium is Streptococcus pneumoniae. Atypical organisms (Mycoplasma, Legionella, Chlamydophila) and viruses (influenza, COVID-19) also cause it. In Pakistan, always keep tuberculosis in mind, because it can look exactly like ordinary pneumonia.
Recognising pneumonia
- Cough, sputum (green, yellow or rusty), fever, breathlessness, pleuritic chest pain.
- Older patients may have only confusion, falls or not eating.
- Signs: fast breathing, low SpO₂, crackles, bronchial breathing, dullness to percussion over the affected area.
History
- How long: days suggests ordinary pneumonia; weeks suggests TB, cancer or another cause.
- Weight loss, night sweats, coughing blood, TB contacts.
- Recent hospital stay (hospital-acquired pneumonia needs different antibiotics).
- Swallowing problems, stroke, alcohol, seizures: aspiration.
- Diabetes, heart, kidney or lung disease, steroids, HIV.
- Recent antibiotics, including from a pharmacy without prescription.
- Allergies, and what the allergy actually was.
Severity: CURB-65
- Confusion (new).
- Urea above 7 mmol/L (above 42 mg/dL). Many Pakistani labs report urea in mg/dL. If your lab reports BUN, the cut-off is about 20 mg/dL.
- Respiratory rate 30 or more.
- Blood pressure: systolic below 90 or diastolic 60 or less.
- Age 65 or more.
Use the CURB-65 calculator if you are unsure.
- Usually home with oral antibiotics
- Admit if SpO₂ below 92% or poor support at home
- Usually admit
- Oral or IV antibiotics depending on how unwell
- Admit, IV antibiotics
- Senior review
- Consider HDU or ICU, especially with 4–5
CURB-65 is a guide, not a rule. A young patient with SpO₂ of 86% scores 0 and still needs admission. Look at the patient and the oxygen.
Other causes of a "pneumonia" picture
| Condition | Points towards it | Test that helps |
|---|---|---|
| Tuberculosis | Weeks of cough, weight loss, night sweats, upper lobe cavity | Sputum GeneXpert, smear |
| Heart failure | Orthopnoea, raised JVP, bilateral shadowing, no fever | BNP, echo |
| Pulmonary embolism | Sudden breathlessness, pleuritic pain, clear X-ray or wedge shadow | CT pulmonary angiogram |
| Lung cancer | Smoker, weight loss, coughing blood, shadow that does not clear | CT chest |
| COVID-19 or influenza | Outbreak, bilateral changes, contacts | Viral swab |
| Aspiration | Stroke, drunk, seizure, right lower lobe | History |
Investigations
| Test | Why |
|---|---|
| Chest X-ray | Confirms consolidation, shows effusion or cavity |
| SpO₂, ABG if below 92% or COPD | Respiratory failure |
| CBC, CRP | Infection, baseline for monitoring |
| Urea, creatinine, electrolytes | CURB-65 and kidney function |
| Blood cultures | Moderate or high severity, before antibiotics |
| Sputum culture | If it can be produced |
| Sputum GeneXpert | Any cough over 2 weeks, cavity, weight loss, or not settling |
| Legionella and pneumococcal urine antigen | High severity, where available |
| Lactate | If septic |
Antibiotics
Use your hospital policy if there is one. Common choices for adults with normal kidney function:
- Amoxicillin by mouth
- Penicillin allergy: doxycycline or clarithromycin
- 5 days
- Amoxicillin plus clarithromycin by mouth
- IV if unable to take oral
- 5 days
- Co-amoxiclav IV plus clarithromycin IV
- Or ceftriaxone IV plus clarithromycin or azithromycin
- 5 days, review at 48 hours
Avoid empirical levofloxacin or moxifloxacin unless your policy or a true penicillin allergy requires it. TB is common in Pakistan, and these drugs can partly treat it, hiding the diagnosis and encouraging resistance.
- Hospital-acquired pneumonia (onset 48 hours or more after admission): broader cover, such as piperacillin-tazobactam, per local policy.
- Aspiration pneumonia: cover for anaerobes is often not needed unless there is an abscess or empyema. Follow local policy.
- Switch IV to oral when the fever has settled for 24–48 hours, the patient is eating and observations are stable.
Supportive care
- Oxygen: keep SpO₂ 94–98% (88–92% if CO₂ retainer).
- Fluids: many patients are dry. Give IV fluids if they cannot drink or the BP is low.
- Paracetamol for fever and pleuritic pain.
- Clot prevention: enoxaparin unless contraindicated.
- Sit up and get moving as soon as possible. Chest physiotherapy if sputum is hard to clear.
Not getting better?
- Check the diagnosisIs it really pneumonia? Think TB, heart failure, PE, cancer.
- Repeat the chest X-rayLook for an effusion, abscess or cavity.
- Tap any effusionA pleural fluid pH below 7.2 or pus means empyema: chest drain.
- Review the culturesChange antibiotics to the organism's sensitivities.
- Send sputum for GeneXpertIf not done already.
- Senior reviewConsider CT chest and the respiratory team.
Before discharge
- Stable observations for 24 hours, eating, SpO₂ normal on air.
- Finish the 5-day course.
- Explain that tiredness and cough can last several weeks.
- Repeat chest X-ray at about 6 weeks for smokers and anyone over 50, to make sure the shadow has cleared (to exclude an underlying cancer).
- Stop smoking. Influenza and pneumococcal vaccines for high-risk patients.
Common mistakes
- Delaying antibiotics to wait for sputum or the X-ray report in a septic patient.
- Relying on CURB-65 and ignoring a low SpO₂.
- Reaching for a fluoroquinolone first.
- Not considering TB when the cough has lasted weeks.
- Missing an empyema in a patient whose fever does not settle.
Frequently asked questions
What is the CURB-65 score?
One point each for new confusion, urea above 7 mmol/L (42 mg/dL), respiratory rate 30 or more, systolic BP below 90 or diastolic 60 or less, and age 65 or more. 0–1 is low, 2 moderate and 3–5 high severity.
Which antibiotic is used for community-acquired pneumonia?
Low severity: amoxicillin. Moderate: amoxicillin plus clarithromycin. High severity: IV co-amoxiclav or ceftriaxone plus clarithromycin. Follow your hospital policy.
How long should pneumonia be treated?
Five days for most adults, reviewed at day 3 and extended only if the patient is not improving.
When should I suspect tuberculosis instead of pneumonia?
Cough for more than 2 weeks, weight loss, night sweats, coughing blood, upper lobe changes or a cavity, or no response to standard antibiotics. Send sputum for GeneXpert.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A 71-year-old man with pneumonia is newly confused. Urea 54 mg/dL (9 mmol/L), RR 32, BP 96/58. What is his CURB-65 score?
Answer: 5. Confusion (1), urea above 7 mmol/L (about 42 mg/dL) (1), RR 30 or more (1), systolic below 90 or diastolic 60 or less (1), age 65 or more (1). Score 5: high severity, IV antibiotics, senior review and consider HDU.
- 1: Far too low.
- 4: The diastolic BP of 58 scores a point even with a systolic above 90.
- 2: Underestimates the severity.
- 3: Count all five: confusion, urea, respiratory rate, BP and age.
2. A 30-year-old woman has community-acquired pneumonia with CURB-65 of 0, but SpO₂ is 88% on air. What is the best plan?
Answer: Admit for oxygen and treatment. CURB-65 does not include oxygen saturation. Hypoxia, inability to take oral medicine or social concerns override a low score.
- Discharge with review in 48 hours: Hypoxia is not safe at home.
- Nebulised salbutamol and discharge: Doesn't treat the hypoxia from pneumonia.
- Discharge on oral amoxicillin: Low oxygen needs admission regardless of the score.
- Repeat CURB-65 tomorrow: The decision is needed now.
3. A patient with pneumonia is still febrile on day 4 of antibiotics. The chest X-ray shows a new pleural effusion. What is the next step?
Answer: Ultrasound-guided diagnostic pleural tap. A persistent fever with a new effusion suggests a complicated parapneumonic effusion or empyema. Pleural fluid pH below 7.2, pus or organisms mean a chest drain is needed.
- CT pulmonary angiogram: PE is not the main concern here.
- Change antibiotics and repeat X-ray in a week: An infected effusion may need drainage.
- Furosemide: This is not a transudate from fluid overload.
- Bronchoscopy: Not the first step.
4. A 72-year-old has pneumonia with confusion, urea 9 mmol/L, RR 32/min and BP 85/50 mmHg. What is his CURB-65 score and management?
Answer: 5 — hospital, consider ICU. CURB-65: Confusion, Urea > 7 mmol/L, RR ≥ 30, BP (systolic < 90 or diastolic ≤ 60), age ≥ 65 — one point each. 0–1: home; 2: hospital; 3–5: severe — consider ICU. Severe CAP: IV co-amoxiclav or ceftriaxone plus a macrolide. S. pneumoniae is the commonest cause.
- 2 — oral antibiotics at home: A score of 2 underestimates; all five criteria are present.
- 3 — outpatient review: A score of 3 is wrong, and outpatient review is unsafe.
- 1 — home treatment: A score of 1 underestimates severely.
5. An elderly stroke patient with dysphagia develops fever and right lower lobe consolidation 3 days after admission. What is the most appropriate management?
Answer: Antibiotics + swallow assessment. Aspiration pneumonia commonly affects dependent segments (right lower lobe — straighter right main bronchus; posterior upper lobe if supine). Risks: stroke/dysphagia, reduced consciousness, alcohol, seizures, GORD. Treat with antibiotics (co-amoxiclav; hospital-acquired — broader Gram-negative cover per local policy), formal swallow assessment (speech and language therapy), modified diet, positioning, oral hygiene; NG feeding if unsafe swallow.
- Antifungals: This is not fungal.
- Continue oral feeding unchanged: Continued oral feeding risks recurrent aspiration.
- High-dose steroids: Steroids are not indicated.
6. Which bacterium has no cell wall, so it is not affected by penicillins?
Answer: Mycoplasma pneumoniae. Mycoplasma lacks a cell wall (its membrane contains sterols), so it does not Gram stain and beta-lactams do not work. It causes atypical pneumonia in young adults, with cold agglutinins (IgM) that can cause haemolysis. Treat with macrolides or doxycycline.
- Streptococcus pneumoniae: Has a cell wall; penicillin works.
- Haemophilus influenzae: Has a cell wall.
- Klebsiella pneumoniae: Has a cell wall.
- Legionella pneumophila: Has a cell wall, though treated with macrolides as it is intracellular.
7. A man with diabetes and heavy alcohol use has upper lobe pneumonia with thick, red 'currant jelly' sputum. Which organism is most likely?
Answer: Klebsiella pneumoniae. Klebsiella is an encapsulated, lactose-fermenting Gram-negative rod. It causes severe pneumonia in alcohol users and people with diabetes, often after aspiration, with currant jelly sputum, upper lobe involvement and cavitation or abscess.
- Streptococcus pneumoniae: Rusty sputum; lobar pneumonia in healthy adults.
- Mycoplasma pneumoniae: Atypical pneumonia in young people.
- Legionella pneumophila: Linked to water systems; hyponatraemia, diarrhoea.
- Haemophilus influenzae: COPD exacerbations.
References and dose sources
- NICE NG138: Pneumonia (community-acquired), antimicrobial prescribing
- ATS/IDSA guideline for community-acquired pneumonia (2019)
- BTS pleural guideline 2023
- NICE NG33 — tuberculosis
- NICE NG250 — pneumonia: diagnosis and management (2025)
- BTS — community-acquired pneumonia
- Amoxicillin dosing: Drugs.com: Amoxicillin dosage (see also our amoxicillin dose page)
- Clarithromycin dosing: Drugs.com: Clarithromycin dosage (see also our clarithromycin dose page)
- Doxycycline dosing: Drugs.com: Doxycycline dosage (see also our doxycycline dose page)
- Co-amoxiclav (amoxicillin with clavulanic acid) dosing: Drugs.com: Amoxicillin/clavulanate dosage (see also our co-amoxiclav (amoxicillin with clavulanic acid) dose page)
- Ceftriaxone dosing: Drugs.com: Ceftriaxone dosage (see also our ceftriaxone dose page)
- Azithromycin dosing: Drugs.com: Azithromycin dosage (see also our azithromycin dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.