Community- and hospital-acquired pneumonia

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Viruses dominate in preschool children, while Streptococcus pneumoniae remains an important bacterial cause. Mycoplasma pneumoniae is more common at school age, but age cannot identify the organism reliably.

Pathogens reach alveoli by inhalation, microaspiration or less often blood spread. Inflammatory exudate fills air spaces, reducing ventilation and creating crackles, bronchial breathing and hypoxaemia.

Clinical tachypnoea is sensitive but nonspecific. Fever, pain, bronchiolitis and metabolic acidosis also increase rate; count for a full minute in a calm child.

Community antibiotic choice prioritises narrow coverage because most stable children recover and broad exposure drives diarrhoea, allergy labels and resistance.

A 3-day course applies only to clinically stable, non-severe community pneumonia in eligible ages. Extend or reassess when fever or instability persists; do not shorten hospital-acquired or complicated infection by analogy.

Healthcare-associated organisms reflect unit ecology and prior exposure. Gram-negative bacilli, Staphylococcus aureus and resistant flora become more likely after ventilation or prolonged admission.

Pleural inflammation begins as free-flowing sterile fluid and may progress to infected loculations and pus. Persistent fever and unilateral findings are key clinical clues.

Radiographic change can lag recovery, so routine follow-up imaging is unnecessary after uncomplicated clinical resolution. Repeat for lobar collapse, round pneumonia, effusion or persistent symptoms.

Hydration must support perfusion without worsening respiratory status. Enteral intake is preferred when safe; sepsis boluses require small weight-based aliquots and reassessment.

Discharge requires improving work, stable room-air oxygenation, oral intake, an effective oral antibiotic and family safety-netting.

Key points

Pneumonia is infection of lung parenchyma. In children it is diagnosed clinically from fever, cough, tachypnoea, recession, crackles or bronchial breathing and systemic effect; viral and bacterial features overlap.
Use age-specific respiratory rate and the whole child. Hypoxaemia, work, perfusion, alertness, drinking, age and comorbidity determine severity more reliably than auscultation alone.
First line for non-severe community-acquired bacterial pneumonia is oral amoxicillin. Current NICE uses 3 days for most children aged 3 months–11 years when clinically stable, and 5 days for age 12–17 or more severe disease.
NICE age doses for 3 days: 3–11 months 125 mg three times daily; 1–4 years 250 mg three times daily; 5–11 years 500 mg three times daily. Verify BNF-C, allergy and renal function.
Use a macrolide when atypical pathogens are suspected or amoxicillin is unsuitable according to current guidance; do not combine routinely in mild preschool pneumonia.
Severe community pneumonia generally needs intravenous co-amoxiclav, adding clarithromycin if atypical infection is suspected, then oral step-down once clinically stable.
Do not routinely request chest radiography, blood tests or microbiology for a stable child managed in the community. Imaging does not reliably distinguish viral from bacterial infection.
In hospital, obtain radiography for severe disease, diagnostic uncertainty, complications or poor response. Lung ultrasound is useful for pleural fluid; ultrasound does not replace chest radiography for all parenchymal questions.
Hospital-acquired pneumonia begins at least 48 hours after admission and was not incubating on arrival. Select antibiotics from local resistance, prior cultures, aspiration and device exposure; send respiratory and blood cultures when feasible before treatment.
Review at 48–72 hours. Improvement includes reduced fever and effort, better oxygenation and drinking; cough may persist after bacterial control.
Complicated effusion or empyema needs respiratory and surgical input, ultrasound characterisation, pleural sampling when drained and antibiotics; do not repeatedly tap a large infected collection without a drainage plan.
Prevention includes vaccination, smoke avoidance, aspiration assessment, hand hygiene, oral care and minimising unnecessary ventilation and antibiotics.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Community respiratory pathogens

Viruses, pneumococcus, group A streptococcus, Staphylococcus aureus and atypical organisms cause age- and context-dependent community disease.

Hospital flora and devices

Ventilation, admission beyond 48 hours, previous antibiotics and airway devices select Gram-negative and resistant organisms. within the child-specific clinical phenotype.

Aspiration and host vulnerability

Swallow dysfunction, neuromuscular disease, immunodeficiency and chronic lung disease alter organisms, distribution and severity. within the child-specific clinical phenotype.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Alveolar inflammation
Pathogen replication recruits neutrophils and fluid into alveoli, producing consolidation and impaired ventilation. during progression of the respiratory disorder.
2
Ventilation-perfusion mismatch
Perfusion through poorly aerated lung creates hypoxaemia and compensatory tachypnoea with increased respiratory work. during progression of the respiratory disorder.
3
Systemic inflammatory response
Cytokine-driven fever and vasodilation can progress to capillary leak, shock and organ dysfunction. during progression of the respiratory disorder.
4
Pleural extension
Inflammation crosses the pleura, creating effusion that may become infected, fibrinous, loculated and purulent. during progression of the respiratory disorder.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Respiratory phenotype

Record cough, fever, rate, recession, grunting, crackles, bronchial breathing, pleuritic pain and asymmetry.

Physiological severity

Assess saturation, colour, effort, perfusion, consciousness, urine and ability to drink using age-appropriate observations.

Acquisition context

Establish community onset versus at least 48 hours after admission, ventilation, aspiration, devices, antibiotics and prior cultures.

Host risk

Document age, vaccination, prematurity, neurological, cardiac, respiratory and immune disease and recent influenza or varicella.

Pleural signs

Look for unilateral reduced expansion and breath sounds, dull percussion, persistent fever and positional pain.

Trajectory

Record symptom and antibiotic timing because nonresponse at 48–72 hours directs complication and resistance review.

Red flags requiring action

Saturation below 90%, cyanosis, grunting, severe recession, apnoea, exhaustion or altered consciousness requires urgent admission and respiratory support.
Shock, prolonged capillary refill, hypotension, oliguria, mottling or high lactate indicates sepsis and needs time-critical treatment.
Infant under 3 months with suspected bacterial pneumonia or fever needs same-day paediatric assessment because deterioration and bacteraemia risk is greater.
Pleuritic pain, unilateral reduced air entry, dullness, persistent fever or scoliosis toward one side suggests parapneumonic effusion or empyema.
Failure to improve within 48–72 hours requires review of adherence, organism, resistance, effusion, abscess, foreign body, TB and immune or structural disease.
Hospital onset, recent ventilation, tracheostomy, aspiration or known resistant colonisation requires local microbiology advice rather than routine community antibiotics.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line community assessmentFirst stepFirst line
Why
Diagnose clinically and decide oral treatment versus hospital referral.
Interpretation and limitations
A stable child without hypoxaemia or complication needs no routine imaging or blood testing.
02
Chest radiograph in hospital or complication
Why
Assess extent, effusion, collapse, cavitation or an alternative diagnosis.
Interpretation and limitations
Radiographic pattern cannot reliably determine viral versus bacterial cause and may lag clinical recovery.
03
Pleural ultrasound
Why
Confirm, size and characterise pleural fluid and guide safe drainage planning.
Interpretation and limitations
Echogenic or loculated fluid supports complicated disease but management uses clinical severity and multidisciplinary review.
04
Blood and respiratory cultures
Why
Guide narrow therapy in severe, hospital-acquired or complicated pneumonia.
Interpretation and limitations
Collect before antibiotics when this causes no delay; prior treatment reduces sensitivity and colonisation must be distinguished from infection.
05
Inflammatory, renal and gas assessment
Why
Monitor severe infection, sepsis, organ function and ventilation.
Interpretation and limitations
Trends support response but no CRP threshold alone determines bacterial cause or discharge.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Bronchiolitis or viral wheeze

Diffuse wheeze or crackles after coryza, particularly under 2, may represent viral small-airway disease without bacterial pneumonia.

Asthma

Recurrent variable wheeze and bronchodilator response without persistent fever or focal signs supports an asthma attack.

Foreign-body aspiration

Sudden choking, persistent asymmetry and recurrent same-lobe infection requires bronchoscopy evaluation. when timing, examination and trajectory are integrated.

Tuberculosis

Chronic cough, exposure, weight loss, lymphadenopathy or nonresolving radiographic disease warrants the specialist TB pathway. when timing, examination and trajectory are integrated.

Cardiac failure or aspiration

Hepatomegaly, murmur, feeding diaphoresis or feed-linked wet cough suggests noninfectious or recurrent aspiration disease. when timing, examination and trajectory are integrated.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01CommunityTreat stable disease narrowlyFirst stepA child has non-severe community-acquired pneumonia and can drink.

1Give oral amoxicillin using the current age dose and 3- or 5-day course.
2Provide fluids, antipyretic comfort and explicit breathing and hydration advice.
3Review if worsening at any time or not beginning to improve within 3 days.

02SevereAdmit and stabiliseHypoxaemia, severe work, sepsis, young age or inability to drink is present.

1Give oxygen, monitored fluid and time-critical intravenous antibiotics after cultures when feasible.
2Use co-amoxiclav and add clarithromycin only according to severe community and atypical guidance.
3EscalationEscalate respiratory or intensive-care support and step down to oral treatment when stable.

03HospitalUse local resistance dataPneumonia begins at least 48 hours after admission or follows ventilation.

1Obtain respiratory and blood cultures and review prior organisms and antibiotics.
2Start the local severity- and unit-specific empirical regimen with microbiology input.
3Narrow promptly from culture and response and address aspiration and device prevention.

04NonresponseSearch for complicationFever, hypoxaemia or effort fails to improve within 48–72 hours.

1Confirm diagnosis, dose, delivery, adherence and microbiology.
2Image for effusion, collapse, abscess or foreign body and consider TB or immune disease.
3Drain complicated pleural infection and revise antibiotics with respiratory, surgical and microbiology teams.

Key medicines and prescribing safety1 treatment · regimens, roles and cautions

First-line narrow oral antibacterial treatment for uncomplicated community-acquired pneumonia.

Amoxicillin

Non-severe community pneumonia: age 3–11 months 125 mg orally three times daily; 1–4 years 250 mg three times daily; 5–11 years 500 mg three times daily, usually 3 days. Age 12–17 years 500 mg three times daily for 5 days.

Verify current NICE and BNF-C dosing, weight, renal function and immediate versus non-immediate penicillin allergy. Review if not improving within 3 days; do not apply short courses to severe or complicated disease.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Respiratory failure and sepsis

Extensive consolidation can cause profound hypoxaemia, shock, multi-organ dysfunction and death. when recognition or effective treatment is delayed.

Parapneumonic effusion or empyema

Pleural infection restricts ventilation and sustains fever until adequately drained and treated. when recognition or effective treatment is delayed.

Necrosis, abscess or air leak

Virulent infection may destroy parenchyma, form cavities, pneumatoceles, bronchopleural fistula or pneumothorax. when recognition or effective treatment is delayed.

Persistent structural damage

Severe, recurrent or inadequately resolved infection can reveal or contribute to bronchiectasis and focal obstruction. when recognition or effective treatment is delayed.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Trend saturation, work, perfusion, alertness, fever and drinking more than inflammatory markers alone.
Review antibiotic dose against current weight, renal function, allergy phenotype and route.
Reassess at 48–72 hours for clinical improvement and pleural signs.
Monitor fluid balance carefully in respiratory failure and sepsis.
For HAP, review cultures daily and de-escalate broad therapy when possible.
After empyema, coordinate imaging, drainage care, antibiotic duration and respiratory follow-up.
Investigate recurrent same-site pneumonia for foreign body or structural obstruction.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Three days is conditional

The short amoxicillin course applies to stable community pneumonia in specified ages, not severe, hospital-acquired or complicated infection.

Imaging cannot name the pathogen

Lobar and interstitial patterns overlap, so antibiotic decisions use age, severity and acquisition context.

Persistent fever suggests pleura

Failure after appropriate treatment with unilateral reduced breath sounds should prompt ultrasound for effusion or empyema.

Hospital is a microbiological context

Prior antibiotics, ventilation and unit ecology matter more than simply choosing a broader version of community treatment.

Cough outlasts infection

Clinical recovery is judged by fever, breathing, oxygenation and function; residual cough alone need not extend antibiotics.

11Common pitfallsFrequent interpretation and management errors.

01
Do not diagnose bacterial pneumonia from a radiograph alone.
02
Do not routinely image a stable community-managed child.
03
Do not use a 3-day course for severe or complicated disease.
04
Do not use community empirical treatment for ventilator-associated pneumonia.
05
Do not delay sepsis antibiotics for difficult cultures.
06
Do not give repeated large fluid boluses without reassessment.
07
Do not ignore persistent unilateral signs or fever after 48–72 hours.
08
Do not routinely repeat radiography after uncomplicated clinical resolution.