Symptoms of Mycoplasma Pneumonia
Mycoplasma pneumoniae lung infection typically presents with fever, persistent cough, headache, arthralgia (joint pain), and crackles on lung examination, particularly in school-aged children, though the clinical picture can closely resemble other pneumonias including bacterial and viral infections. 1
Core Pulmonary Symptoms
The hallmark respiratory symptoms include:
- Persistent cough - This is the most characteristic feature, typically lasting 3-4 weeks and often nonproductive initially 2
- Fever - Usually present but may be low-grade rather than high fever 3
- Crackles (rales) on lung auscultation 1, 2
- Wheezing - Occurs in approximately 30% of cases, more common in older children 1
Important clinical caveat: The presence of wheeze can cause mycoplasma pneumonia to be confused with asthma, especially when diagnosed without chest radiography 1. This is a common diagnostic pitfall.
Systemic and Extra-Pulmonary Manifestations
Beyond respiratory symptoms, mycoplasma commonly causes:
- Headache - frequently reported 1
- Arthralgia (joint pain) 1
- Malaise and fatigue 4
- Gastrointestinal symptoms - nausea/vomiting in 33% of children 3
- Skin manifestations - present in 25% of cases 3
- Abdominal pain in older children (reflecting referred pain from diaphragmatic pleura) 1
- Chest pain 1
- Ear pain 5
Age-Related Presentation Patterns
School-aged children (≥5 years): This is the classic demographic. The combination of fever, arthralgia, headache, cough, and crackles in a school-child strongly suggests mycoplasma infection 1, 4.
Younger children (2-6 years): Account for approximately 30% of positive cases during epidemics, with similar symptoms to viral infections 3.
Infants (<2 years): Only 4% of cases, but can present with severe lower respiratory tract infection 3.
Key Distinguishing Features (and Their Limitations)
While mycoplasma has been called "atypical pneumonia," the clinical presentation often cannot reliably distinguish it from pneumococcal or staphylococcal pneumonia, or even adenoviral illness when wheezing is prominent 1. This is critical to understand - you cannot diagnose mycoplasma on clinical grounds alone.
The British Thoracic Society guidelines emphasize that when wheeze is present alongside respiratory symptoms, consider viral or mycoplasmal infection rather than primary bacterial pneumonia 1.
Physical Examination Findings
- Respiratory signs may be surprisingly mild relative to radiographic findings 6, 7
- Crackles and decreased breath sounds are common 6
- Rhonchi may be present 6
- Bronchial breathing and pleural effusion are NOT present at symptom onset 1
Clinical Course
The disease typically shows slow progression with persistent cough as the dominant feature 4. Unlike pneumococcal pneumonia which starts abruptly with high fever and tachypnea, mycoplasma tends to have a more gradual onset 7.
Practical Clinical Approach
When evaluating suspected mycoplasma pneumonia, look for this constellation:
- Persistent, often nonproductive cough (lasting weeks)
- Fever (may be low-grade)
- Systemic symptoms (headache, malaise, joint pain)
- Crackles on examination
- ± Wheezing (30% of cases)
- Extra-pulmonary manifestations (GI symptoms, rash, ear pain)
- School-age child or young adult (peak incidence 5-30 years) 2
Critical point: The diagnosis requires laboratory confirmation (PCR or serology) because clinical and radiographic findings overlap extensively with other causes of pneumonia 6, 4.