Tonsillitis and Pharyngitis Organism-Specific Therapy

Updated: Jan 24, 2019
Author: Udayan K Shah, MD, FACS, FAAP; Chief Editor: Michael Stuart Bronze, MD 

Specific Organisms and Therapeutic Regimens

Organism-specific therapeutic regimens for tonsillitis and pharyngitis are provided below, including those for Streptococcus pyogenes; groups B, C, and G β-hemolytic streptococci; Fusobacterium necrophorum; Arcanobacterium haemolyticum; and Neisseria gonorrhoeae.[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]

Streptococcus pyogenes (group A beta-hemolytic streptococcus)

Adult dosage:

  • Penicillin V 500 mg PO BID for 10d or

  • Benzathine penicillin G 1.2 million U IM once or

  • Amoxicillin 500-875 mg PO q12h or 250-500 PO q8h for 10d or

  • Cephalexin 500 mg PO BID for 10d or

  • Cefdinir 600 mg PO once daily for 10d or

  • Cefprozil 500 mg PO once daily for 10d

Pediatric dosage:

  • Penicillin V 25-50 mg/kg/day divided q6h for 10d or

  • Benzathine penicillin G 25,000 U/kg IM once (maximum 1.2 million U) or

  • Amoxicillin 50 mg/kg/day PO in 2 or 3 divided doses for 10d or

  • Amoxicillin-clavulanate 500-875 mg PO q12h for 10d or

  • Cefuroxime axetil 20 mg/kg/day in 2 divided doses for 4-10d or

  • Cefdinir 14 mg/kg q24h for 10d or

  • Cefprozil 15 mg/kg/day in 2 divided doses for 10d

Adult dosage if penicillin allergic:

  • Azithromycin 500 mg PO daily for 5d or

  • Clarithromycin 250 mg PO q12h for 10d or

  • Clindamycin 7 mg/kg/day in 3 divided doses (maximum 1.8 g/day) for 10d

Pediatric dosage if penicillin allergic:

  • Azithromycin 12 mg/kg PO once daily for 5d or

  • Clarithromycin 250 mg PO q12h for 10d or

  • Clindamycin 7 mg/kg/day PO in 3 divided doses (maximum 1.8 g/day) for 10d

Group B, C and G beta-hemolytic streptococci

Adult dosage:

  • Penicillin V 500 mg PO BID for 10d or

  • Benzathine penicillin G 1.2 million U IM once or

  • Amoxicillin 500-875 mg PO q12h or 250-500 PO q8h for 10d

Pediatric dosage:

  • Penicillin V 25-50 mg/kg/day divided q6h for 10d or

  • Benzathine penicillin G 25,000 U/kg IM once (maximum 1.2 million U) or

  • Amoxicillin 50 mg/kg/day PO in 2 or 3 divided doses for 10d

Adult dosage if penicillin allergic:

  • Azithromycin 500 mg PO daily for 5d or

  • Clarithromycin 250 mg PO q12h for 10d or

  • Clindamycin 7 mg/kg/day in 3 divided doses (maximum 1.8 g/day) for 10d

Pediatric dosage if penicillin allergic:

  • Azithromycin 12 mg/kg PO once daily for 5d or

  • Clarithromycin 250 mg PO q12h for 10d or

  • Clindamycin 7 mg/kg/day PO in 3 divided doses (maximum 1.8 g/day) for 10d

Arcanobacterium haemolyticum

Suspect when teenager or young adult patient has scarlatiniform rash and negative rapid strep test.

Adult dosage:

  • Erythromycin 250 mg PO QID

Pediatric dosage:

  • Erythromycin succinate 20 mg/kg PO BID for 10d

Neisseria gonorrhoeae

Diagnosis should be confirmed by culture on Thayer-Martin medium.

  • Ceftriaxone 125 mg IM once

  • Also recommended to treat for Chlamydia trachomatis infection at the same time, unless this organism has been ruled out; treat with azithromycin 1 g PO once ordoxycycline 100 mg PO q12h for 7d

Corynebacterium diphtheriae

Extremely rare in the United States; diagnosis should be suspected in cases of pharyngitis with pseudomembranes.

Fusobacterium necrophorum

See the list below:

  • More prevalent in patients between ages 14 and 20 years [16]
  • Associated with Lemierre syndrome
  • Treatment with penicillin or cephalosporin
  • Azithromycin resistant