What is the treatment for Mycoplasma pneumoniae infections?

Mycoplasma pneumoniae: Symptoms, Transmission, and Treatment

Symptoms and Clinical Presentation

Mycoplasma pneumoniae causes respiratory tract infections that mimic viral syndromes, presenting as pneumonia, bronchitis, bronchiolitis, pharyngitis, and croup. 1

• The infection occurs worldwide, with highest incidence in school-aged children and second highest in children under 5 years 1
• Epidemics occur at 4-7 year intervals 1
• Most cases are mild and treated on an outpatient basis 1
• Dermatologic, neurological, cardiac, renal, and pulmonary complications can occur, though their frequency is not well-established 1
• Patients with humoral immunodeficiency may develop severe infections with joint involvement 1

Transmission and Carrier State

• The carrier state may persist for several months after infection 1
• Immunity appears to increase with age, and rates of subsequent reinfection are low among those previously infected 1
• In immunocompromised patients, particularly those with humoral immunodeficiency, the carrier state may persist indefinitely 1

Treatment

First-Line Therapy: Macrolides

Macrolide antibiotics are the recommended first-line treatment for M. pneumoniae infections in both children and adults. 2

• Azithromycin 500 mg once daily for 5 days is the preferred regimen 2, 3
• Clarithromycin 7-14 days is an alternative macrolide option 2
• Erythromycin is less commonly used due to gastrointestinal intolerance 2

Critical age-based consideration: For children under 5 years with suspected pneumonia where the pathogen is unknown, amoxicillin should be used first-line since S. pneumoniae is more common in this age group 2. However, if M. pneumoniae is specifically suspected based on clinical presentation, macrolides become appropriate even in children under 5 2.

Monitoring Response to Macrolides

Do not assume treatment failure at 48 hours when using macrolides—M. pneumoniae infections characteristically take 2-4 days for fever resolution, unlike the <24 hours typical for pneumococcal pneumonia. 2, 4

• Patients should be reviewed if deteriorating or not improving after 48 hours 2
• If no improvement after 48-72 hours of macrolide therapy, reassessment is necessary and consider alternative diagnosis or complications 2
• Hospitalization is warranted if no improvement after 5 days of appropriate therapy or if condition worsens 2

Alternative Therapy: Tetracyclines and Fluoroquinolones

If macrolide resistance is suspected or treatment fails after 48-72 hours, switch to tetracyclines or fluoroquinolones. 2

Tetracyclines (for patients ≥8 years old):

• Doxycycline 100 mg PO twice daily for 7-14 days 2, 5
• Minocycline 200 mg PO/IV first dose, then 100 mg PO/IV twice daily for 7-14 days 2

Fluoroquinolones (adults only):

• Levofloxacin 750 mg PO/IV daily for 7-14 days 2, 6
• Moxifloxacin 400 mg PO/IV daily for 7-14 days 2

Macrolide Resistance Considerations

Macrolide resistance is now a major global concern, with prevalence ranging from 0-15% in Europe and USA, approximately 30% in Israel, and up to 90-100% in Asia. 7, 8

• Resistance is caused by point mutations in the 23S rRNA gene, leading to high-level resistance 7, 8
• Macrolide-resistant infections result in longer duration of fever, cough, and hospital stay 7
• Children infected with macrolide-resistant strains experience persistent fever with extended antibiotic therapy and minimal decrease in bacterial load 9
• Acquired resistance to tetracyclines and fluoroquinolones has never been reported in clinical isolates 7

Severe or Refractory Cases

For severe cases requiring hospitalization, consider combination therapy with a β-lactam plus a macrolide. 2

• Refractory M. pneumoniae pneumonia reflects excessive immune response and may require immunomodulators such as corticosteroids or intravenous immunoglobulin (IVIG) in addition to appropriate antimicrobials 9
• Intravenous antibiotics should be considered for patients with severe disease unable to take oral medications 2

Treatment Duration

• Atypical pneumonia (M. pneumoniae) requires a minimum of 14 days with macrolide therapy, which is longer than the 10 days required for pneumococcal pneumonia with β-lactams 2
• Alternative agents (tetracyclines or fluoroquinolones) are typically given for 7-14 days 2

Common Pitfalls to Avoid

• Do not discontinue macrolides prematurely at 48 hours—fever resolution takes 2-4 days in M. pneumoniae infection 2, 4
• Do not use fluoroquinolones in children or tetracyclines in children under 8 years old 2, 7
• Do not assume β-lactams will be effective—M. pneumoniae lacks a cell wall and is intrinsically resistant to all β-lactams 7, 8
• Be aware that azithromycin can cause serious allergic reactions including anaphylaxis, Stevens-Johnson Syndrome, hepatotoxicity, QT prolongation, and C. difficile-associated diarrhea 3