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Lower respiratory tract infections continue to be a major health problem despite advances in antimicrobial therapies. Controversy persists regarding optimal diagnostic approaches and treatment choices for pneumonia.

Pneumonia has classically been considered in terms of the infecting organism (Table 9–8)(eFigures 9–8, 9–9, 9–10, and 9–11). This approach facilitates discussion of characteristic clinical presentations but is a limited guide to patient management since specific microbiologic information is rarely available at initial presentation. More recent classification schemes emphasize epidemiologic factors that predict etiology and guide initial therapy. Pneumonia may be classified as community-acquired (CAP) or nosocomial and, within the latter, as hospital-acquired (HAP) or ventilator-associated (VAP). These categories are based on differing settings and infectious agents and require different diagnostic and therapeutic interventions. Anaerobic pneumonia and lung abscess can occur in both hospital and community settings and warrant separate consideration.

Table 9–8.Characteristics of selected pneumonias.
eFigure 9–8.

Streptococcus pneumoniae.

eFigure 9–9.

Haemophilus influenzae.

eFigure 9–10.

Klebsiella pneumoniae.

eFigure 9–11.

Moraxella catarrhalis.


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