What is the most suitable antibiotic for a 16-year-old male with a history of allergic reaction (rash) to amoxicillin (amoxicillin) as a child, presenting with streptococcal pharyngitis (strep throat) and weighing approximately 150 pounds?

From the Guidelines

For a 16-year-old male weighing approximately 150 lb with strep throat and an amoxicillin allergy (rash as a child), azithromycin is the recommended antibiotic, with a dosage of 12 mg/kg once daily (maximum 500 mg) for 5 days 1. The patient's weight is approximately 150 lb, which is around 68 kg, so the appropriate dosage would be 500 mg on the first day, followed by 250 mg daily for the next four days (5 days total).

• Alternatively, clindamycin 300 mg three times daily for 10 days could be used, as it is also effective against Group A Streptococcus 1.
• It's essential to complete the full course of antibiotics even if symptoms improve before finishing.
• The patient should start feeling better within 48 hours of beginning treatment.
• Adequate hydration and over-the-counter pain relievers like acetaminophen or ibuprofen can help manage symptoms.
• If symptoms worsen or don't improve after 48-72 hours, medical reassessment is necessary.
• The patient should avoid close contact with others for the first 24 hours of antibiotic treatment to prevent spreading the infection. These recommendations are based on the strongest and most recent evidence from the Infectious Diseases Society of America and the American Heart Association, which prioritize the use of azithromycin and clindamycin in patients with penicillin allergy 1.

From the FDA Drug Label

Pharyngitis/Tonsillitis The recommended dose of azithromycin for children with pharyngitis/tonsillitis is 12 mg/kg once daily for 5 days.

PEDIATRIC DOSAGE GUIDELINES FOR PHARYNGITIS/TONSILLITIS (Age 2 years and above, see PRECAUTIONS—Pediatric Use.) Based on Body Weight PHARYNGITIS/TONSILLITIS: (5-Day Regimen) Dosing Calculated on 12 mg/kg/day for 5 days.

Weight 200 mg/5 mL Total mL per Treatment Course Total mg per Treatment Course Kg Lbs. Day 1–5 40 88 12.5 mL (2½ tsp) 62.5 mL 2500 mg

For a 16-year-old male weighing approximately 150 lb (68 kg), azithromycin is a suitable alternative for the treatment of strep throat, especially considering the patient's allergy to amoxicillin.

• The recommended dose for pharyngitis/tonsillitis in this age group is 12 mg/kg once daily for 5 days 2.
• However, since the patient is over 12 years old, the dosage may be adjusted to the adult dose, which is typically 500 mg once daily for 5 days.
• It is essential to note that penicillin is usually the first-line treatment for strep throat, but azithromycin can be used as an alternative in patients with a penicillin allergy 2.
• The patient's weight and age should be considered when determining the appropriate dose, and the treatment should be guided by the severity of the infection and the patient's overall health status.
• Azithromycin has been shown to be effective in eradicating susceptible strains of Streptococcus pyogenes from the nasopharynx, but susceptibility tests should be performed to ensure the bacteria are susceptible to the antibiotic 2.

From the Research

Antibiotic Options for Strep Throat in a 16-Year-Old Male with Amoxicillin Allergy

• The patient has a history of amoxicillin allergy, which limits the treatment options for strep throat.
• According to the studies, penicillin and amoxicillin are first-line antibiotics for strep throat, but the patient's allergy to amoxicillin rules out these options 3.
• First-generation cephalosporins are recommended for patients with nonanaphylactic allergies to penicillin, which may be a suitable alternative for this patient 3.
• Macrolides such as clarithromycin and azithromycin can be used as alternative treatments, but there is significant resistance to these antibiotics in some parts of the United States 3.
• A study comparing 10 days of clarithromycin therapy to 5 days of azithromycin therapy found that clarithromycin was more effective in eradicating the organism 4.
• Another study found that 5 days of clarithromycin or amoxicillin/clavulanate treatment had clinical efficacy comparable to 10 days of penicillin V treatment, but amoxicillin/clavulanate and penicillin V were bacteriologically more effective than clarithromycin 5.
• Azithromycin has been shown to have similar clinical efficacy to penicillin V, but lower bacteriologic eradication rates 6.

Recommended Treatment

• Based on the studies, a first-generation cephalosporin or a macrolide such as clarithromycin or azithromycin could be considered as alternative treatments for this patient.
• However, the patient's weight and age should be taken into account when determining the appropriate dosage and treatment duration.
• It is essential to consult with a healthcare professional to determine the best course of treatment for this patient, considering their individual needs and medical history 3, 4, 5, 6.