Antibiotic Choice and Dosing for 5-Year-Old with Strep A (21.3 kg)
Amoxicillin 50 mg/kg/day divided into 2 doses for 10 days is the first-line treatment, which equals approximately 533 mg (about 11 mL of 250 mg/5 mL suspension) twice daily for this 21.3 kg child. 1
First-Line Antibiotic Selection
Amoxicillin is the preferred antibiotic for Group A Streptococcal pharyngitis due to its effectiveness, palatability, and twice-daily dosing that improves adherence compared to penicillin V. 1, 2
The recommended dose is 50-75 mg/kg/day divided into 2 doses, with most guidelines favoring 50 mg/kg/day for uncomplicated cases. 1, 3
For this 21.3 kg child: 50 mg/kg/day = 1,065 mg total daily dose, given as 533 mg twice daily (approximately 11 mL of 250 mg/5 mL suspension per dose). 1
Treatment duration must be 10 days to prevent acute rheumatic fever and ensure complete eradication of Group A Streptococcus. 1, 3, 2
Critical Dosing Considerations
The maximum single dose should not exceed 1000 mg per administration, which is well above this child's calculated dose. 1
Amoxicillin should be administered at the start of a meal to minimize gastrointestinal intolerance. 3
Patients stop being contagious after 24 hours of appropriate antibiotic therapy. 1
Alternative Options for Penicillin Allergy
For non-anaphylactic penicillin allergy: Use narrow-spectrum cephalosporins such as cephalexin (75-100 mg/kg/day in 3-4 doses) or cefadroxil for 10 days. 1
For Type I hypersensitivity (anaphylactic) reactions: Clindamycin 10-20 mg/kg/day divided into 3 doses is the preferred alternative. 1
Macrolides (azithromycin, clarithromycin) are options but have inferior bacteriologic efficacy and should be reserved for true penicillin allergy. 2, 4
Monitoring and Follow-Up
Clinical improvement should occur within 48-72 hours of initiating therapy. 1
If no improvement occurs within this timeframe, reevaluation is necessary to consider complications or alternative diagnoses. 1
Complete the full 10-day course even if symptoms resolve earlier to prevent rheumatic fever and ensure bacterial eradication. 1, 3
Common Pitfalls to Avoid
Do not use shorter treatment courses (such as 5-7 days) for Group A Streptococcal pharyngitis, as 10 days is required to prevent acute rheumatic fever. 1, 3
Do not use high-dose amoxicillin (90 mg/kg/day) for simple pharyngitis—this dosing is reserved for pneumonia or resistant organisms. 1
Avoid macrolides as first-line therapy due to increasing resistance and inferior eradication rates compared to beta-lactams. 4, 5
Ensure proper reconstitution of oral suspension and shake well before each use; refrigeration is preferable but not required. 3