Mycoplasma pneumoniae

Background

• Atypical bacterium within the genus Mycoplasma
• Incidence fluctuates with epidemic years every 3 to 7 years and non-epidemic years mostly very low rates
• More common in late summer and fall during epidemic years

Clinical Manifestations

• Most commonly causes subacute pneumoniae within influenza-like illness followed by persistent cough and malaise
• Hematologic manifestations include IgM-mediated hemolytic anemia (cold agglutinin disease), which is typically self-limited and does not require transfusion, and rarely immune thrombocytopenia
• Dermatologic manifestations can include
  • Mild erythematous maculopapular or vesicular lesions
  • Urticaria
  • Erythema multiforme or Stevens-Johnson syndrome
  • Reactive infectious mucocutaneous eruption (RIME)
• CNS manifestations are rare but include encephalitis more commonly than meningitis, peripheral neuropathy, transverse myelitis, acute disseminated encephalomyelitis, Guillain-Barré syndrome, cranial nerve palsy, and cerebellar ataxia
• Cardiac manifestations include pericarditis, myocarditis, cardiac thrombus, and conduction abnormalities
• Other extrapulmonary manifestations include: hepatitis (usually mild), mild and non-specific GI complaints, arthralgias and myalgias (with rare arthritis), and rare case reports of other possible manifestations

Diagnosis

• PCR from NP swab
• Serology can be helpful in making retrospective diagnosis

Investigations

• CBC often shows a mild hemolytic anemia, with low hemoglobin and high bilirubin, LDH, and reticulocytes
  • Coombs and col-agglutinin titres aretypically positive though these tests are not usually needed
• Normal to mildly elevated white count
• Mild liver enzyme abnormalities
• Chest x-ray shows reticulonodular or patchy opacities, bilaterally or unilaterally
  • Occasional small pleural effusions

Management

• Mostly self-limited
• When treated, usually treated with macrolides, tetracyclines or fluoroquinolones
  • Unclear amount of macrolide resistance in Canada