Hospital-acquired pneumonia

Hospital-acquired or nosocomial pneumonia refers to a new episode of pneumonia occurring at least 2 days after admission to hospital. The term includes post-operative and certain forms of aspiration pneumonia, and pneumonia or bronchopneumonia developing in patients with chronic lung disease, general debility or those receiving assisted ventilation.

Aetiology

The factors predisposing to the development of pneumonia in a hospitalised patient are listed in Box 13.47. The elderly are particularly at risk and this condition now occurs in 2-5% of all hospital admissions

The most important distinction between hospital- and community-acquired pneumonia is the difference in the spectrum of pathogenic organisms, with the majority of hospital-acquired infections caused by Gram-negative bacteria. These include Escherichia, Pseudomonas and Klebsiella species. Infections caused by Staph. aureus (including multidrug-resistant-MRSA-forms) are also common in hospital, and anaerobic organisms are much more likely than in pneumonia acquired in the community. This profile of organisms in part reflects the high rate of colonisation of the nasopharynx of hospital patients with Gram-negative bacteria, together with the poor host defences and general inability of the severely ill or semiconscious patient to clear upper airway and respiratory tract secretions.

Clinical features

The clinical features and investigation of patients with hospital-acquired pneumonia are very similar to community-acquired pneumonia (see pp. 526-528). In the elderly or debilitated patient who develops acute bronchopneumonia (or 'hypostatic pneumonia') symptoms of acute bronchitis are followed after 2 or 3 days by increased cough and sputum purulence associated with a rise in temperature. Breathlessness and central cyanosis may then appear, but pleural pain is uncommon. In the early stages the physical signs are those of acute bronchitis followed by the development of crepitations. There is a neutrophil leucocytosis and the chest radiograph shows mottled opacities in both lung fields, chiefly in the lower zones.

Management

Adequate Gram-negative coverage is usually obtained with:

- third-generation cephalosporin (e.g. cefotaxime) plus an aminoglycoside (e.g. gentamicin)

imipenem or

- monocyclic β-lactam (e.g. aztreonam) plus flucloxacillin.

Physiotherapy is of particular importance in the immobile and elderly, and adequate oxygen therapy, fluid support and monitoring are essential. The mortality from hospital-acquired pneumonia is high (approximately 30%).

Дата добавления: 2015-11-14