Mycoplasma pneumonia

Mycoplasma pneumonia is a type of community-acquired pneumonia caused by the organism Mycoplasma pneumoniae

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.

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.

Most patients recover well although a small proportion of patients may develop bronchiectasis in the affected region or Swyer James syndrome.

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Article information

rID: 25082
System: Chest
Tags: cases, cases
Synonyms or Alternate Spellings:
  • Mycoplasma pneumoniae pneumonia
  • Mycoplasma pneumoniae pneumonia (MPP)
  • Pulmonary mycoplasma pneumoniae infection

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