What is Mycoplasma pneumoniae and its treatment in children and young adults?

Mycoplasma pneumoniae: Overview and Management

What is Mycoplasma pneumoniae?

Mycoplasma pneumoniae is a unique bacterium lacking a cell wall that causes community-acquired respiratory tract infections, particularly in school-aged children and young adults, accounting for 4-39% of all pneumonia cases. 1, 2

Key Characteristics

• Structural uniqueness: M. pneumoniae lacks a cell wall, making it intrinsically resistant to all beta-lactam antibiotics (penicillins, cephalosporins) that target cell wall synthesis 3

• Age distribution:

  • Most common in school-aged children and young adults 3, 4
  • Children over 5 years have significantly higher infection rates (42%) compared to those under 5 years (15%) 1, 2
  • Some studies report 23% incidence even in children aged 3-4 years, higher than traditionally expected 1, 2

• Epidemiology: Epidemics occur at intervals of 4-7 years, with infections occurring both endemically and epidemically worldwide 3, 4

Clinical Presentation

M. pneumoniae typically presents with a slowly progressive course over 3-5 days, characterized by fever (>38.5°C), malaise, sore throat, low-grade fever, headache, arthralgia, and cough. 5, 6

• Respiratory symptoms: Cough, crackles on auscultation, and wheeze in approximately 30% of cases 5
• Systemic symptoms: Fever, headache, arthralgia, malaise 5
• Additional findings: Chest pain and abdominal pain can occur in older children 5

Diagnostic Approach

Chest radiographs cannot reliably distinguish M. pneumoniae from other bacterial or viral pneumonias, and diagnosis is primarily clinical based on age and symptom pattern. 1, 6

• Clinical suspicion: Suspect M. pneumoniae in school-aged children presenting with the characteristic triad of malaise, sore throat, and low-grade fever with slowly progressive symptoms 5, 6

• Diagnostic limitations:

  • Serological testing is the most common diagnostic method but has age-related interpretation challenges 2
  • 40-70% of community-acquired pneumonia cases have no identified pathogen even with comprehensive testing 2
  • Mixed infections occur in 8-40% of cases 1, 2

• Imaging indications: Routine chest radiographs are not necessary for outpatient management of uncomplicated cases 1, 6

Treatment

Macrolide antibiotics are the first-line treatment for M. pneumoniae pneumonia, with azithromycin (5-day course) or clarithromycin (7-14 day course) as preferred agents. 5, 3

Antibiotic Selection by Age

• Children under 5 years: Amoxicillin is first-line for empiric treatment since viral pathogens predominate, but add macrolides if M. pneumoniae is specifically suspected 1, 6

• Children 5 years and older: Macrolide antibiotics may be used as first-line empirical treatment given higher prevalence of M. pneumoniae in this age group 1, 6

Specific Macrolide Regimens

• Azithromycin: 5-day course (10 mg/kg on Day 1, then 5 mg/kg on Days 2-5 for pneumonia) 7, 3
• Clarithromycin: 7-14 day course 3
• Erythromycin: Alternative option 1

Macrolide Resistance Considerations

Macrolide resistance has been spreading globally, with prevalence ranging from 0-15% in Europe/USA, approximately 30% in Israel, and up to 90-100% in Asia. 3

• Alternative antibiotics if resistance suspected:
  • Tetracyclines (doxycycline, minocycline) for 7-14 days—contraindicated in children under 8 years 3
  • Fluoroquinolones (levofloxacin) for 7-14 days—contraindicated in all children 3

Supportive Care

• Oxygen therapy: Provide if oxygen saturation is ≤92% to maintain saturation above 92% 1, 5
• Antipyretics and analgesics: Use to keep the child comfortable and help with coughing 1, 5
• Hydration: Ensure adequate hydration; if IV fluids needed, give at 80% basal levels and monitor electrolytes 1
• Avoid chest physiotherapy: Not beneficial and should not be performed 1

Follow-up and Monitoring

• Outpatient management: Review if deteriorating or not improving after 48 hours on treatment 1, 5
• Inpatient monitoring: Re-evaluate if child remains febrile or unwell 48 hours after admission 1

Clinical Outcomes

• Typical course: Most infections are mild and treated on an outpatient basis 4
• Severe disease: Fulminant M. pneumoniae pneumonia accounts for 0.5-2% of all cases, primarily affecting young adults with no underlying disease 8
• Complications: Extrapulmonary manifestations can involve dermatologic, neurological, cardiac, renal systems, though frequency data are limited 4, 9
• Carrier state: May persist for several months after infection 4