What is the most likely diagnosis and the appropriate dosing of co‑amoxiclav (amoxicillin/clavulanic acid) suspension 125 mg/5 mL and paracetamol for a 5‑year‑old girl weighing 27 kg with a 2‑day history of fever and a productive cough with green sputum?

Diagnosis and Antibiotic Management

This 5‑year‑old girl with fever and productive cough with greenish sputum most likely has community‑acquired bacterial pneumonia, and she should receive co‑amoxiclav (amoxicillin/clavulanate) at 90 mg/kg/day of the amoxicillin component divided into two doses, which equals approximately 19.5 mL of the 125 mg/5 mL suspension twice daily for 7–10 days.

Most Likely Diagnosis

• Bacterial community‑acquired pneumonia (CAP) is the most probable diagnosis when a child presents with fever plus productive cough yielding greenish (purulent) sputum 1.
• Greenish sputum strongly suggests bacterial rather than viral etiology in this clinical context 1.
• At 5 years of age, both typical bacterial pathogens (Streptococcus pneumoniae) and atypical organisms (Mycoplasma pneumoniae, Chlamydophila pneumoniae) must be considered 2.

Co‑Amoxiclav (Augmentin) Dosing Calculation

Weight‑Based Calculation for This Patient

• For a 27 kg child with presumed bacterial pneumonia, the IDSA/PIDS guidelines recommend 90 mg/kg/day of the amoxicillin component divided into 2 doses 2.
• Calculation: 27 kg × 90 mg/kg/day = 2,430 mg total daily dose of amoxicillin 3.
• Per‑dose amount: 2,430 mg ÷ 2 doses = 1,215 mg per dose 3.
• Volume using 125 mg/5 mL suspension: (1,215 mg ÷ 125 mg) × 5 mL = 48.6 mL per dose 4.

Critical Dosing Error in Your Formulation

• The 125 mg/5 mL suspension you have is grossly inadequate for this child's weight and indication 4.
• This concentration is designed for much younger/smaller children (typically 1–6 years weighing 10–18 kg) 4.
• You need to obtain a higher‑concentration suspension (e.g., 400 mg/5 mL or 600 mg/5 mL formulation) to deliver the required dose in a reasonable volume 4.

Correct Practical Approach

• Request co‑amoxiclav 400 mg/5 mL suspension from the pharmacy 4.
• Using 400 mg/5 mL: (1,215 mg ÷ 400 mg) × 5 mL = 15.2 mL per dose, twice daily 4.
• Alternatively, if available, co‑amoxiclav ES‑600 (600 mg/5 mL): (1,215 mg ÷ 600 mg) × 5 mL = 10.1 mL per dose, twice daily 5.

Rationale for High‑Dose Co‑Amoxiclav

• High‑dose amoxicillin‑clavulanate (90 mg/kg/day) is specifically indicated for community‑acquired pneumonia in fully immunized children to provide optimal coverage against penicillin‑resistant Streptococcus pneumoniae and β‑lactamase‑producing organisms 3, 4.
• The 90 mg/kg/day regimen achieves tissue concentrations that overcome penicillin‑resistant S. pneumoniae with MICs up to 2–4 mg/L 5.
• Co‑amoxiclav is preferred over plain amoxicillin when β‑lactamase‑producing Haemophilus influenzae or Moraxella catarrhalis are suspected, which is common in children with purulent sputum 2.

Treatment Duration

• Complete a full 7–10 day course of therapy for bacterial pneumonia 2.
• Most guidelines recommend 10 days for pneumonia specifically 3, 4.

Paracetamol (Acetaminophen) Dosing

• For fever and discomfort: 15 mg/kg per dose, every 4–6 hours as needed 1.
• For this 27 kg child: 27 kg × 15 mg/kg = 405 mg per dose (round to 400 mg) 1.
• Maximum daily dose: 60 mg/kg/day = 1,620 mg/day (do not exceed 4 doses in 24 hours) 6.
• Paracetamol helps keep the child comfortable and may help with coughing 2.

Expected Clinical Response and Monitoring

• Fever should resolve within 24–48 hours after starting effective antibiotics 1, 3.
• Overall clinical improvement (reduced respiratory distress, better feeding) should be evident within 48–72 hours 2, 1.
• Cough may persist beyond fever resolution but should gradually diminish 1.

When to Reassess

• Re‑evaluate at 48–72 hours if any of the following occur 2, 1:
  • Persistent or worsening fever
  • Deterioration of respiratory symptoms
  • Lack of any clinical improvement
  • Emergence of new signs (increased work of breathing, reduced oral intake)

Management of Non‑Response

• If no improvement after 48–72 hours, consider atypical pathogens (Mycoplasma, Chlamydophila) and add or switch to azithromycin 2, 1.
• Azithromycin dosing: 10 mg/kg on day 1 (270 mg), then 5 mg/kg/day (135 mg) on days 2–5 2.
• Obtain chest radiography to rule out complications (e.g., empyema) when clinical response is inadequate 2.

Critical Pitfalls to Avoid

• Do NOT use the 125 mg/5 mL suspension at the calculated volume (48.6 mL per dose) – this is impractical and will lead to poor adherence 4.
• Chest physiotherapy provides no benefit in pediatric pneumonia and should be omitted 2, 1.
• Ensure adequate hydration; if IV fluids are required, administer at approximately 80% of maintenance volume 2, 1.
• Verify the suspension concentration before dispensing to avoid dosing errors 3, 4.