What is the treatment for secondary bacterial infections in patients with infectious mononucleosis (mono)?

Treatment of Secondary Bacterial Infections in Patients with Infectious Mononucleosis

Secondary bacterial infections in patients with infectious mononucleosis should be treated with appropriate antibiotics based on culture results, but antibiotics should not be used routinely as bacterial superinfection is uncommon (occurring in less than 3% of cases). 1

Incidence and Recognition of Secondary Bacterial Infections

• Secondary bacterial infections in infectious mononucleosis are relatively rare

  • Less than 3% of patients with infectious mononucleosis develop Group A beta-hemolytic streptococcal superinfection 1
  • The inflamed pharynx and necrotic tonsils of infectious mononucleosis are seldom subject to bacterial superinfection 1

• Clinical signs that may suggest secondary bacterial infection:

  • Worsening symptoms after initial improvement
  • New onset of purulent discharge
  • Persistent high fever beyond the expected course
  • Localized pain or tenderness beyond typical presentation

Diagnostic Approach

• Obtain throat cultures when bacterial superinfection is suspected 1

  • Do not rely solely on clinical appearance as EBV pharyngitis can mimic bacterial infection
  • Cultures are essential to confirm bacterial pathogens and determine antibiotic susceptibility

• Laboratory testing:

  • Complete blood count with differential (to assess lymphocytosis and atypical lymphocytes) 2
  • Microbiological cultures from appropriate sites (throat, blood, urine) 3
  • Consider multiplex PCR testing in critically ill patients to rapidly identify pathogens 3

Treatment Algorithm

1. Confirm bacterial infection with appropriate cultures before starting antibiotics

   • Avoid empiric antibiotics without confirmation of bacterial infection

2. For confirmed Group A Streptococcal pharyngitis:

   • First-line: Penicillin V 4
   • Alternative: First-generation cephalosporins or macrolides (if penicillin allergic)
   • AVOID ampicillin and amoxicillin due to high risk (90%) of rash in patients with EBV infection 4

3. For severe infections or immunocompromised patients:

   • Consider broader coverage based on suspected pathogens and local resistance patterns 3
   • For immunocompromised patients with severe infections, consider combination therapy with agents active against both gram-positive and gram-negative bacteria 3

4. For secondary bacterial pneumonia:

   • Follow hospital-acquired pneumonia guidelines 3
   • Consider antipseudomonal coverage in critically ill patients 3

Important Caveats and Pitfalls

• Avoid ampicillin/amoxicillin in patients with infectious mononucleosis even when treating confirmed bacterial infections, as these antibiotics frequently cause a maculopapular rash that is not a true allergy 4

• Do not prescribe antibiotics routinely for infectious mononucleosis without confirmed bacterial infection 1, 5

• Monitor for Clostridioides difficile-associated diarrhea when antibiotics are used, especially in patients with prolonged hospitalization 6

• Consider drug interactions between antibiotics and other medications the patient may be taking 3

• Temporarily discontinue bispecific antibody therapy in patients receiving such treatment until infection resolution 3

Duration of Therapy

• For most secondary bacterial infections, 5-7 days of appropriate antibiotic therapy is sufficient 3
• Continue antibiotics until resolution of signs, symptoms, and inflammatory markers 3
• Longer courses may be needed for complicated infections or in immunocompromised hosts

Special Considerations

• In immunocompromised patients:

  • Lower threshold for obtaining cultures and starting appropriate antibiotics 3
  • Consider broader antimicrobial coverage initially 3
  • More vigilant monitoring for response to therapy 3

• For critically ill patients with secondary bacterial infections:

  • Consider double antipseudomonal antibiotics based on local epidemiology 3
  • Obtain appropriate cultures before starting antibiotics when possible 3

By following these guidelines, clinicians can appropriately identify and treat the uncommon but potentially serious secondary bacterial infections that may complicate infectious mononucleosis while avoiding unnecessary antibiotic use.