Management of hospital-acquired pneumonia

Hospital-acquired pneumonia (HAP) remains an important cause of morbidity, affecting between 0.5 and 1% of all hospital admissions, and has the highest mortality among all nosocomial infections. About 90% of HAPs are caused by bacteria, with Gram-negative organisms being responsible for about 60% of all cases. Antibiotic therapy is effective in reducing HAP morbidity and mortality. Empirical intravenous antibiotic therapy should be initiated as soon as the clinical criteria for diagnosing pneumonia are met. The choice of antibiotics should be based on assessment of three factors: (1) the extent of illness of the patient at the time of diagnosis, (2) the presence of host risk-factors for infection with specific pathogens, and (3) the time of onset of HAP after hospitalization. From these evaluations, a list of likely pathogens and possible antibiotic choices follow. Monotherapy with a second-or third-generation cephalosporin, or a beta-lactam/beta-lactamase inhibitor combination, is effective for patients without specific risk-factors. For patients with risk-factors, combination antibiotic therapy is indicated. The appropriate combination therapy depends an the risk factor present and the severity of illness. Invasive diagnostic techniques are indicated for patients not responding to antibiotics. Quantitative bronchoscopic broncho-alveolar lavage (BAL) has mean sensitivity and specificity of more than 80%, and similar results have been obtained for protected specimen brushing (PSB). In selected patients transthoracic needle aspiration (TNA) has the highest specificity, and a positive predictive value of 100%, but its sensitivity is 61%.