Mycoplasma pneumonia is a type of community-acquired pneumonia caused by the organism Mycoplasma pneumoniae. It is usually grouped under an atypical pneumonia.
It is relatively common in the paediatric population where it is considered the most common community-acquired pneumonia in 5 to 20-year-olds (may account for 40% of such cases 7). It may account for 10-15% of community-acquired pneumonia in adults. In adults, mycoplasma can rarely result in a bronchiolitis without giving a pneumonia.
M. pneumoniae is the smallest organism which can be cultured in vitro and lacks a cell wall, hence it is resistant to the penicillins. It spreads via inhalation of aerosolised droplets containing the microorganisms. It initially involves the peribronchovascular interstitium and then extends to the adjacent alveoli.
- immune haemolytic anaemia
- pericarditis and myocarditis
- transverse myelitis
- Guillain-Barre syndrome
- Stevens-Johnson syndrome
There can be variable chest radiographic features, although four different patterns have been described 1. No pattern is, however, pathognomonic:
- peribronchial and perivascular interstitial infiltrates - reticular densities most common ~49% (can be patchy with a segmental or non-segmental distribution)
- airspace consolidation ~38%
- reticulonodular opacification ~8%
- nodular or mass-like opacification ~5%.
Bilateral peribronchial perivascular interstitial infiltrates in central and middle lung zones have also been described. Lower lobes are most commonly involved.
Other reported plain film findings include bilateral lesions, pleural effusion (uncommon - in ~25% of cases) and hilar lymphadenopathy.
Areas of ground-glass attenuation and air-space consolidation have been reported as being frequent on HRCT (~80% of cases 2)
In about 60% of cases, areas of consolidation may have a lobular distribution evident on CT.
Intrapulmonary nodules can also be seen (~90% of cases) and these tend to have a predominantly centrilobular distribution 3.
Other findings include thickening of the bronchovascular bundles.
Treatment and prognosis
Most patients recover well although a small proportion of patients may develop bronchiectasis in the affected region or Swyer James syndrome.
- 1. Hsieh SC, Kuo YT, Chern MS et-al. Mycoplasma pneumonia: clinical and radiographic features in 39 children. Pediatr Int. 2007;49 (3): 363-7. doi:10.1111/j.1442-200X.2007.02363.x - Pubmed citation
- 2. Reittner P, Müller NL, Heyneman L et-al. Mycoplasma pneumoniae pneumonia: radiographic and high-resolution CT features in 28 patients. AJR Am J Roentgenol. 2000;174 (1): 37-41. doi:10.2214/ajr.174.1.1740037 - Pubmed citation
- 3. Miyashita N, Sugiu T, Kawai Y et-al. Radiographic features of Mycoplasma pneumoniae pneumonia: differential diagnosis and performance timing. BMC Med Imaging.9 (1): 7. BMC Med Imaging (full text) - doi:10.1186/1471-2342-9-7 - Free text at pubmed - Pubmed citation
- 4. Gückel C, Benz-Bohm G, Widemann B. Mycoplasmal pneumonias in childhood. Roentgen features, differential diagnosis and review of literature. Pediatr Radiol. 1989;19 (8): 499-503. Pubmed citation
- 5. Finnegan O, Fowles S, White R. Thorax. 1981;36 (6): . doi:10.1136/thx.36.6.469
- 6. Cameron DC, Borthwick RN, Philp T. The radiographic patterns of acute mycoplasma pneumonitis. Clin Radiol. 1977;28 (2): 173-80. Pubmed citation
- 7. Kashyap S, Sarkar M. Mycoplasma pneumonia: Clinical features and management. Lung India. 2010;27 (2): 75-85. doi:10.4103/0970-2113.63611 - Free text at pubmed - Pubmed citation
- 8. John SD, Ramanathan J, Swischuk LE. Spectrum of clinical and radiographic findings in pediatric mycoplasma pneumonia. Radiographics. 2001;21 (1): 121-31. doi:10.1148/radiographics.21.1.g01ja10121 - Pubmed citation