What is the recommended treatment for strep (streptococcal) throat in a patient with mononucleosis (mono)?

Treatment of Streptococcal Pharyngitis in Patients with Mononucleosis

For patients with confirmed streptococcal pharyngitis who also have mononucleosis, amoxicillin should be avoided and penicillin V or alternative antibiotics such as clindamycin should be used instead to prevent the development of an ampicillin rash. 1

Diagnosis Confirmation

Before initiating treatment, it's crucial to confirm both conditions:

1. Streptococcal pharyngitis diagnosis:

   • Use Centor Criteria to assess likelihood of Group A Streptococcal (GAS) pharyngitis:
     • Tonsillar exudates
     • Tender anterior cervical lymph nodes
     • Lack of cough
     • Fever
   • Score of 3-4 warrants testing with Rapid Antigen Detection Test (RADT) and/or throat culture 1
   • Throat culture remains the gold standard with results taking 24-48 hours 1

2. Mononucleosis diagnosis:

   • Look for characteristic symptoms: significant fatigue, palatal petechiae, posterior cervical or auricular adenopathy 2
   • Confirm with atypical lymphocytosis (≥20%) or heterophile antibody test 2

Treatment Algorithm

1. Antibiotic Selection:

   • First-line: Penicillin V for 10 days 1

     • Dosing: Follow standard dosing regimens
     • Twice-daily dosing is as effective as more frequent dosing 3

   • For penicillin-allergic patients:

     • Clindamycin: 300-450 mg orally three times daily for 10 days 1
     • Erythromycin can also be considered 4

   • Avoid amoxicillin in patients with mononucleosis due to high risk of ampicillin rash

2. Duration of Therapy:

   • Complete the full 10-day course of antibiotics to prevent complications such as acute rheumatic fever 1

3. Supportive Care:

   • Focus on symptom relief:
     • Cold liquids or ice chips
     • Gargling with cold water
     • Medicated throat lozenges every two hours
     • NSAIDs for fever and pain (more effective than acetaminophen)
     • Avoid hot liquids and spicy foods 1

Important Considerations and Pitfalls

1. Ampicillin/Amoxicillin Rash:

   • Up to 90% of mononucleosis patients treated with amoxicillin develop a non-allergic maculopapular rash
   • This is not a true penicillin allergy but a reaction specific to the combination of EBV infection and aminopenicillins

2. Activity Restrictions:

   • Patients with mononucleosis should be withdrawn from contact or collision sports for at least four weeks after symptom onset to prevent splenic rupture 2
   • Activity should be guided by the patient's energy level 2

3. Return to School/Work:

   • Patients should complete at least 24 hours of antibiotics before returning to school or work to reduce transmission risk 1

4. Treatment Failure Monitoring:

   • Patients with worsening symptoms after antibiotic initiation or symptoms lasting 5+ days after starting treatment require reevaluation 1
   • Fatigue and other symptoms of mononucleosis may persist for several months 2

5. Not Recommended:

   • Corticosteroids, acyclovir, and antihistamines are not recommended for routine treatment of infectious mononucleosis (exception: corticosteroids may benefit patients with respiratory compromise or severe pharyngeal edema) 2

By following this approach, you can effectively treat streptococcal pharyngitis in patients with mononucleosis while avoiding the common pitfall of amoxicillin-induced rash.