Pulmonary haemophilus influenzae infection

Pulmonary haemophilus influenzae infection refers to infection of lung with the organism Haemophilus influenzae which is a gram-negative bacillus.

Epidemiology

The infections can exacerbate chronic obstructive pulmonary disease and can cause pneumonia, particularly in older adults. It can also be part of hospital acquired pneumonia.

Pathology

Haemophilus influenzae is an important pneumonia pathogen because of its severity, high incidence of complications and high mortality. The organism frequently colonizes the human upper respiratory tract, especially the nasopharynx, and is considered to form part of the normal respiratory flora. Most H. influenzae infections are the result of direct extension from the nasopharynx to the lower respiratory tract.

Radiographic features

CT chest

While no particular feature is specific the number of patterns may be present which include

These abnormalities may have a predilection for the peripheral lung parenchyma.

Pleural effusions may be seen in a small portion of patients while mediastinal lymph node enlargement is uncommon.

Treatment and prognosis

Mortality rates in patients with H. influenzae pneumonia have been reported as ranging around 10-42%.