Pneumonia I: Introduction

Pneumonia is a lung parenchymal infection that affects one or both lungs.

Risk factors for pneumonia include air pollution, smoking, corticosteroid and immunosuppressive therapy, stroke, prolonged immobility, inhalation or aspiration of toxic substances, tracheal intubation, abdominal or thoracic surgery, and structural lung disease.

It can be categorized as community-acquired or medical care–associated pneumonia.

Community-acquired pneumonia occurs in the community setting or within the first 48 hours after hospitalization or institutionalization.

The most common causes include Streptococcus pneumoniae and Haemophilus influenzae.

Medical care–associated pneumonia encompasses three forms of pneumonia.

The first is hospital-associated pneumonia, which occurs 48 hours or longer after hospital admission and is not incubated at the time of hospitalization.

Next is ventilator-associated pneumonia, which occurs 48 hours after endotracheal intubation.

Lastly, healthcare-associated pneumonia occurs when the patient develops pneumonia after being hospitalized in an acute care facility for at least two days within 90 days of the infection.