Changing epidemiology of nosocomial bloodstream infections in 11 teaching hospitals in Taiwan between 1993 and 2006

Background/purpose: Healthcare-associated infections, formerly known as nosocomial infections, are one of the most important issues in current practice. Understanding trends in overall infection rates, as well as their incidence and proportion among different causative organisms, can help us to better define our infection control methods and therapy goals. To understand the changing epidemiology of nosocomial bloodstream infections (BSI) in Taiwan, we retrospectively collected nosocomial infection data from 11 hospitals and examined the trends and changing patterns of nosocomial BSI.

Methods: Eleven major teaching hospitals in Taiwan were invited to participate in the study. The overall density of nosocomial infections and major BSI-causing organisms, including Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Candida species, were collected. The distribution of the different Candida species was also recorded. Background parameters from the 11 hospitals, including the size of the hospital, hospital capacity, the number of blood stream infection events, and average length of stay, were also recorded.

Results: The incidence of nosocomial BSI ranged 0.23-2.56 per 1,000 patient-days, which accounted for 8-43% of all nosocomial infections. The most common causative organism of nosocomial bacteremia was S. aureus, ranging 0.88-0.01 per 1,000 patient-days. Overall, the incidence of S. aureus bacteremia has decreased over the last 13 years, but this difference was not statistically significant (p = 0.053). The rate of Candida fungemia (p < 0.01) and A. baumannii (p = 0.03) bacteremia increased significantly. C. albicans accounted for most cases of nosocomial fungemia, ranging from 40% to 80%, followed by Candida tropicalis, Candida parapsilosis and Candida glabrata. However, the incidence varied significantly from hospital to hospital, and the highest incidence was observed in a cancer center.

Conclusion: The overall incidence rate of S. aureus bacteremia in the 11 major hospitals studied had decreased over the last decade, though the difference was not statistically significant. However, the rate of Candida fungemia and A. baumannii bacteremia had increased significantly.