Clinical Features and Complications

A doctor examines a college-aged woman with a stethoscope.

Mycoplasma pneumoniae infections cause a wide array of non-specific symptoms.

Clinical features

Mycoplasma pneumoniae infections can occur in the upper or lower respiratory tract. The bacterium can also cause a wide array of extrapulmonary manifestations without obvious respiratory disease. Therefore, patients may have a highly variable presentation.

Common manifestations

Infection most commonly results in:

  • Tracheobronchitis
  • Pharyngitis
  • Pneumonia
Common symptoms
  • Malaise
  • Fever
  • Cough
  • Headache

Illness onset can be gradual and subacute, slowly progressing to a higher fever and a persistent cough. While the disease can persist for weeks or months, it is frequently mild and self-resolving. The organism may persist for several weeks in the oropharynx despite completion of recommended antimicrobial therapy and resolution of clinical symptoms.

Younger patients may have different manifestations, symptoms

Younger patients often manifest with different clinical characteristics than patients over 5 years of age. For example, infections in younger patients may run subclinical, be mild, and not result in pneumonia. Infections in younger patients are often characterized by coryza and wheezing without concomitant fever, and sometimes include diarrhea and vomiting

Clinical complications

Severe complications are uncommon, but can result in hospitalization and sometimes death. Complications include:

  • Severe pneumonia
  • Exacerbation of asthma
  • Encephalitis
  • Hemolytic anemia
  • Renal dysfunction
  • Gastrointestinal complaints
  • Erythema multiforme, Stevens-Johnson syndrome, or toxic epidermal necrolysis

Incubation period

The incubation period is generally between 1 to 4 weeks; however, shorter and longer durations can occur.