Which antibiotics are effective against Mycoplasma (Mycoplasma) infections?

Antibiotics Effective Against Mycoplasma Infections

Macrolides (particularly azithromycin) and tetracyclines (particularly doxycycline) are the first-line antibiotics for treating Mycoplasma infections, with fluoroquinolones serving as alternative options when resistance is suspected. 1, 2, 3

First-Line Treatment Options

Tetracyclines

• Doxycycline: 100 mg orally twice daily for 7-14 days 2
  • Mechanism: Inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit
  • Highly effective against Mycoplasma pneumoniae
  • Contraindicated in children under 8 years and pregnant women
  • According to the WHO's essential medicines recommendations, doxycycline is categorized as an "Access" antibiotic and is the preferred agent for treating chlamydial and non-gonococcal urethritis, including those caused by Mycoplasma 1

Macrolides

• Azithromycin: 500 mg orally on day 1, then 250 mg daily for 4 days (5-day regimen) 3

  • Alternative dosing: 500 mg daily for 3-5 days
  • Mechanism: Binds to the 23S rRNA of the bacterial 50S ribosomal subunit, inhibiting protein synthesis
  • Safe for use in children and pregnant women
  • Better tolerated than other macrolides
  • For Mycoplasma genitalium specifically, higher dose regimens (2.5g total) may be more effective and less likely to induce resistance than the single 1g dose 4, 5

• Clarithromycin: 500 mg orally twice daily for 7-14 days 1

  • Similar mechanism to azithromycin
  • More drug interactions than azithromycin due to stronger inhibition of P450 enzyme system

Second-Line Treatment Options (for macrolide-resistant infections)

Fluoroquinolones

• Moxifloxacin: 400 mg orally once daily for 7-14 days 6

  • Mechanism: Inhibits bacterial DNA gyrase and topoisomerase IV
  • Effective against macrolide-resistant Mycoplasma strains
  • Contraindicated in children and pregnant women
  • Should be reserved for cases of treatment failure with first-line agents or known macrolide resistance 5

• Levofloxacin: 500-750 mg orally once daily for 7-14 days 1

  • Similar mechanism to moxifloxacin
  • Same contraindications as moxifloxacin

Treatment Considerations

Resistance Patterns

• Macrolide resistance in Mycoplasma pneumoniae has been increasing globally, with rates of:
  • 0-15% in Europe and USA
  • Approximately 30% in Israel
  • Up to 90-100% in some Asian countries 7
• Resistance is associated with point mutations in the 23S rRNA and leads to high-level resistance to macrolides
• Macrolide resistance can result in longer duration of fever, cough, and hospital stay 8

Special Populations

• Children: Macrolides (particularly azithromycin) are preferred due to safety profile
  • For children <5 years: Amoxicillin (90 mg/kg/day in 2 doses)
  • For children ≥5 years with atypical pneumonia: Macrolides 8
• Cystic Fibrosis patients with Mycoplasma abscessus:
  • More complex regimens are required, including oral macrolide (preferably azithromycin) plus multiple additional antibiotics 1

Important Caveats

• Mycoplasma lacks a cell wall, making it intrinsically resistant to all beta-lactams and other cell wall-targeting antibiotics 7, 9
• Single-dose azithromycin (1g) should be avoided for Mycoplasma genitalium due to high rates of treatment failure and development of macrolide resistance 4, 10
• Never use macrolide monotherapy for Mycoplasma abscessus pulmonary disease 1
• Resistance testing should guide therapy when available, particularly for persistent or recurrent infections

Treatment Algorithm

1. Initial empiric therapy: Doxycycline (preferred) or azithromycin (5-day regimen)
2. If patient is <8 years old or pregnant: Use azithromycin
3. If no clinical improvement after 48-72 hours:
   • Consider macrolide resistance
   • Switch to fluoroquinolone (moxifloxacin or levofloxacin) if patient is an adult
   • Consider resistance testing if available
4. For severe infections or immunocompromised patients:
   • Consider combination therapy or consultation with infectious disease specialist

By following this evidence-based approach, clinicians can effectively treat Mycoplasma infections while minimizing the risk of treatment failure and antimicrobial resistance.