Pneumonia

Hospital-acquired pneumonia (HAP) is defined as an episode of pneumonia that presents at least 48 hours after admission to hospital and was not incubating at the time of admission. It is the second most common healthcare-associated infection (HAI) after surgical-site infections and the leading cause of HAI-associated death. Older patients are particularly at risk, as are patients in intensive care units. The term ventilator-associated pneumonia (VAP) is used to describe pneumonia that develops in a person who is mechanically ventilated.

Acute eosinophilic pneumonia is an acute febrile illness (of less than 5 days’ duration), characterised by diffuse pulmonary infilltrates and hypoxic respiratory failure.

Focal unilateral airspace opacication favours bacterial infection,mycobacteria or Nocardia.

Bilateral opacication favours P. jirovecii pneumonia, fungi, viruses and unusual bacteria, e.g. Nocardia

cavitation may be seen with N. asteroides, mycobacteria and fungi  the presence of a ‘halo sign’ (a zone of intermediate attenuation between the nodule and the lung parenchyma) may suggest aspergillosis or other invasive fungal infection  pleural effusions suggest pyogenic bacterial infections and are uncommon in P. jirovecii pneumonia.