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INTRODUCTION

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are the most frequent causes of healthcare-associated infections (HAIs) and represent significant clinical and economic burdens on healthcare systems. Definitions for each of these conditions are provided in Table 129-1. HAP and VAP are frequently associated with multidrug-resistant (MDR) microorganisms, leading to further morbidity and mortality in hospitalized patients. VAP is considered a device-associated HAI and is, therefore, reported to the National Healthcare Safety Network (NHSN), the surveillance branch of the Centers for Disease Control and Prevention (CDC). According to the latest published data from the NHSN, 10,037 cases of VAP were reported from 2015 to 2017.1 This chapter focuses on the epidemiology of infection, the microorganisms responsible for infection, the complexities surrounding the diagnosis, and the preventive and therapeutic management strategies used to combat nosocomial pneumonia.

TABLE 129-1Definitions of Nosocomial Pneumoniaa

EPIDEMIOLOGY

HAP and VAP account for approximately 28% of HAIs and are collectively the most frequent cause of nosocomial infection.2,3 Epidemiologic data estimate an overall prevalence of nosocomial pneumonia in hospitalized patients of 0.89%, with the burden substantially higher among patients in the intensive care unit (ICU).2,3 While the majority of cases of nosocomial pneumonia occur in nonintubated patients, mechanical ventilation is the most important risk factor for pneumonia, increasing the incidence up to 20-fold.2,4,5 Approximately 10% of patients undergoing mechanical ventilation develop VAP.6 In a 1-day point prevalence study involving ICU patients from centers in 88 different countries, investigators found respiratory tract infections were the most common infection in the ICU, accounting for 60.1% of infections. Furthermore, respiratory tract infections were the most frequent reason for antibiotic prescription in the ICU. Overall, greater than 50% of the infections documented in this study were categorized as hospital-acquired or healthcare-associated, rather than community-acquired.3 A multicenter, prospective cohort analysis conducted in Canada demonstrated a VAP rate of 14.8 cases per 1000 ventilator days, with half occurring on or before day 7. While the cumulative risk for developing VAP increased with duration of ICU stay, the daily risk increased until day 5 and then subsequently decreased.7

Determining the economic impact of VAP and the associated morbidity and mortality is challenging. Critically ill patients have multiple, evolving, complex disease processes that make it difficult to isolate VAP as the sole ...

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