New epidemiology for postoperative nosocomial infections.

Changes in health care delivery systems over the last decade have resulted in a major increase in outpatient surgery and a higher severity of illness for inpatients. We sought to determine the effects of this change on the epidemiology of postoperative surgical infections. Historical data on incidence and epidemiology of infection were obtained from peer-reviewed articles published between 1960 and 1999 (MEDLINE). All nosocomial infections in 5035 patients admitted to a tertiary-care university hospital surgical intensive care unit between January 1994 and December 1997 were prospectively identified and classified as wound, urinary tract, bloodstream, or pneumonia. Incidence of bacterial isolates at each site was also recorded. From these data we determined infection rates per 100 admissions. We also identified all device-related nosocomial infections and calculated infection rates. Comparisons between time periods were made. In the 1960s wound infections constituted the predominant postoperative infection at 46 per cent. This was replaced by urinary tract infection in the 1970s (44%) and 1980s (32%) and closely followed by bloodstream infections (25%). In the 1990s nosocomial pneumonia became the most common postoperative infection, comprising 43 per cent of surgical intensive care unit infections. Analysis of the bacteriology also revealed changing trends with primarily gram-positive organisms in the 1960s followed by an increase in methicillin-resistant Staphylococcus in the 1970 to 1980s, and currently resistant gram-negative bacteria predominate. The incidence of fungal infections has steadily increased. This survey identified a new epidemiology for postoperative surgical infections. Over the last several decades the reported wound infections have been markedly decreased and there is little change in urinary tract infection. Nosocomial pneumonia with resistant gram-negative bacteria now predominates along with increased incidence of fungal infections. Currently, postoperative infections are now more severe, involve critical organs, and require close monitoring of the changing patterns of pathogens.

Nosocomial infections in the surgical intensive care unit: a difference between trauma and surgical patients.

In 1970, the Centers for Disease Control and Prevention (CDC) established the National Nosocomial Infection Surveillance System to assist institutions with infection surveillance, data collection, and processing. This facilitates interinstitutional comparison for nosocomial infection rates. Nosocomial infection rates in the surgical intensive care unit have been shown to be different from the medical intensive care unit. Whether there exists a difference in infection rates between trauma and surgical patients in the intensive care unit has not been established. Our objective was to determine whether there is a difference in rates of nosocomial infections between trauma and surgical patients in the surgical intensive care unit. From January 1995 through December 1997, we reviewed 3715 admissions to the surgical intensive care unit and separated them into trauma (1272) or surgical (2443) cases. We documented all nosocomial pneumonias, urinary tract infections, bloodstream infections, and surgical site infections. From these data we determined infection rates per 100 admissions. We also identified all device-related nosocomial infections and calculated infection rate by current CDC standards using number of device infections divided by number of device-days times 1000. We found that the overall trauma patient infection rate was 11.64 per cent compared with 6.43 per cent for surgical patients (P<.001). Using conventional infection rate criteria, trauma patients had higher frequency in the rate of ventilator-associated pneumonia (6.13% vs. 2.50%; P<0.001), urinary tract infection (2.36 versus 1.76; P<0.2), and bloodstream infection (2.52% versus 1.27%; P<0.01). However, when using the CDC guidelines, which correct for the number of device-days for infections, only the difference in rate of pneumonia between the two groups reached statistical significance (23.9 rate for trauma patients vs. 16.7 for the surgery group; P<0.005). We conclude that trauma patients are at higher risk for nosocomial infections than routine surgical patients. Because of this difference, centers should collect and report data separately for trauma and surgical patients in the intensive care unit. Specific attention should be focused on the causes and prevention of increased rates of nosocomial pneumonia in trauma patients.