Mycoplasma pneumoniae

Question 1

What type of pneumonia does it cause? Why is it important to pick up?

Answer 1

Mycoplasma pneumoniae is a cause of atypical pneumonia which often affects younger patients.

Epidemics of Mycoplasma pneumoniae classically occur every 4 years.

It is important to recognise atypical pneumonias as they may not respond to penicillins or cephalosporins due to it lacking a peptidoglycan cell wall.

Question 2

What are the features of Mycoplasma pneumoniae infection?

Answer 2

• the disease typically has a prolonged and gradual onset
• flu-like symptoms classically precede a dry cough
• bilateral consolidation on x-ray
• complications may occur as below

Question 3

What are the complications associated with Mycoplasma pneumonia infection?

Answer 3

• cold agglutins (IgM) may cause an haemolytic anaemia, thrombocytopenia
• erythema multiforme, erythema nodosum, Steven-Johnson Syndrome (epidermis separating from the dermis)
• meningoencephalitis, Guillain-Barre syndrome
• bullous myringitis: painful vesicles on the tympanic membrane
• pericarditis/myocarditis
• gastrointestinal: hepatitis, pancreatitis
• renal: acute glomerulonephritis

Question 4

How is it investigated?

Answer 4

• Diagnosis is generally by PCR sputum and Mycoplasma serology
• Positive cold agglutination test
• Chest x-ray shows reticular nodular shadowing or patchy consolidation, often of 1 lower lobe, and worse than signs suggest

Question 5

How is it treated?

Answer 5

Clarithromycin 500mg / 12hr OR

Doxycycline 200mg loading dose, then 100mg OD, OR

Fluroquinolone (Ciprofloxacin, norfloxacin)