Hospitalizations and deaths caused by methicillin-resistant Staphylococcus aureus, United States, 1999-2005

Abstract

Hospital-acquired infections with Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) infections, are a major cause of illness and death and impose serious economic costs on patients and hospitals. However, the recent magnitude and trend of these infections have not been reported. We used national hospitalization and resistance data to estimate the annual number of hospitalizations and deaths associated with S. aureus and MRSA from 1999 through 2005. During this period, the estimated number of S. aureus-related hospitalizations increased 62%, from 294,570 to 477,927, and the estimated number of MRSA-related hospitalizations more than doubled, from 127,036 to 278,203. Our findings suggest that S. aureus and MRSA should be considered a national priority for disease control.

Figure 1

Estimated methicillin-resistant Staphylococcus aureus (MRSA)–related hospitalization rates, United States, 1999–2005. Rates are no. MRSA-related discharges/1,000 hospitalizations. Error bars represent 95% confidence intervals.

Figure 2

Primary diagnoses of Staphylococcus aureus–related hospitalizations. The most frequent primary diagnosis associated with other S. aureus–related infections was other cellulitis and abscess (International Classification of Diseases [ICD]-9 682), followed by postoperative infection (ICD-9 998.59), infections from an implanted device or graft (ICD-9 996), osteomyelitis (ICD-9 730), and diabetes mellitus (ICD-9 250). Cellulitis and abscess infections increased at a rate >25% per year from 1999 through 2005. No other primary diagnosis infection showed a major increase over this period.

Figure 3

Estimated hospital deaths associated with Staphylococcus aureus and methicillin-resistant S. aureus (MRSA), United States, 1999–2005. Error bars represent 95% confidence intervals.

Figure 4

Percentage of Staphylococcus aureus isolates resistant to methicillin in national surveys, United States, 1999–2004. TSN, The Surveillance Network (data include hospital infections); NNIS, National Nosocomial Infections Surveillance System (data include only intensive care units); SENTRY, includes only skin and soft tissue infections.