What is the appropriate amoxicillin dosage for a child with a suspected bacterial infection and leukocytosis (elevated white blood cell count) of 15.8 x10^9/L?

Amoxicillin Dosing for Children with Suspected Bacterial Infection and Leukocytosis

For a child with suspected bacterial infection and leukocytosis (WBC 15.8 x10^9/L), the recommended amoxicillin dosage is 45-90 mg/kg/day divided into 2-3 doses, with the higher range (90 mg/kg/day) preferred for more severe infections or in areas with high pneumococcal resistance. 1

Dosing Based on Suspected Pathogen and Severity

Respiratory Tract Infections

• For mild to moderate respiratory infections: 45 mg/kg/day divided into 2-3 doses 1
• For severe respiratory infections or in areas with high pneumococcal resistance: 90 mg/kg/day divided into 2 doses 2, 1
• When Streptococcus pneumoniae is suspected: 90 mg/kg/day in 2 doses or 45 mg/kg/day in 3 doses 2

Group A Streptococcal Infections

• For Group A Streptococcal infections: 50-75 mg/kg/day in 2 doses 2, 1
• Treatment should continue for at least 10 days for Group A Streptococcal infections to prevent acute rheumatic fever 2, 3

Haemophilus influenzae Infections

• For H. influenzae (β-lactamase negative): 75-100 mg/kg/day in 3 doses 2
• For H. influenzae (β-lactamase producing): Use amoxicillin-clavulanate instead 2

Dosing Considerations Based on Infection Severity and Patient Factors

Elevated White Blood Cell Count (Leukocytosis)

• The presence of leukocytosis (15.8 x10^9/L) suggests a more significant bacterial infection, which may warrant the higher end of the dosing range 1
• For infections with signs of systemic involvement (including leukocytosis), consider using the higher dosage of 90 mg/kg/day 2, 1

Age-Specific Considerations

• For children aged less than 12 weeks (3 months): Maximum recommended dose is 30 mg/kg/day divided every 12 hours due to incompletely developed renal function 3
• For children aged 3 months and older: Follow standard dosing recommendations based on infection type and severity 3

Administration Guidelines

• Administer at the start of a meal to minimize gastrointestinal intolerance 3
• Twice-daily dosing (higher dose per administration) has been shown to be as effective as three-times-daily dosing and may improve compliance 4, 5
• Treatment should continue for a minimum of 48-72 hours beyond symptom resolution 3

Duration of Therapy

• Standard duration for most bacterial infections: 7-10 days 1
• For Group A Streptococcal infections: Minimum 10 days to prevent acute rheumatic fever 2, 3
• Shorter courses (3 days) may be appropriate for mild infections after clinical improvement, but this is less appropriate with leukocytosis suggesting more severe infection 6

Potential Adverse Effects

• Common adverse effects include gastrointestinal disturbances (diarrhea, nausea, vomiting) 1
• Rash, urticaria, and other hypersensitivity reactions may occur 1
• Higher doses may increase the risk of gastrointestinal side effects, but studies show comparable safety profiles between standard and high-dose regimens 6

Clinical Pearls and Pitfalls

• Elevated white blood cell count (15.8 x10^9/L) suggests a more significant infection that may benefit from higher dosing 1
• Ensure adequate duration of therapy to prevent treatment failure and relapse 3
• Consider local antimicrobial resistance patterns when selecting dosage 2
• Twice-daily dosing may improve adherence compared to three-times-daily dosing while maintaining efficacy 4, 5
• For suspected pneumococcal infections with high resistance, higher dosing (90 mg/kg/day) is recommended 2, 1