Relative frequency of health care-associated pathogens by infection site at a university hospital from 1980 to 2008.

Background: We describe the relative frequency of health care-associated pathogens by infection site over 29 years using hospital-wide surveillance data from a large academic hospital.

Methods: Comprehensive hospital-wide surveillance was provided by trained infection preventionists using Centers for Disease Control and Prevention definitions. Five 5-year blocks and one 4-year block were created for each site: bloodstream infections (BSI), urinary tract infections (UTI), respiratory tract infections (RTI), and surgical site infections (SSI). The blocks of relative frequency of health care-associated pathogens were compared by χ(2) analysis, and trends for each pathogen were estimated by regression analysis.

Results: At least 1 pathogen was isolated from 28,208 (83.5%) of 33,797 health care-associated infections (HAI). Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Enterococcus species, and Clostridium difficile and other anaerobes significantly increased, whereas Escherichia coli, Pseudomonas aeruginosa, Klebsiella species, Enterobacter species, and other streptococci significantly decreased in the relative proportion of pathogens during the study period. By infection site, results showed significant increasing trends of S aureus in UTI, RTI, and SSI; CoNS in BSI and SSI; Candida in SSI; and Enterococcus in BSI and UTI.

Conclusion: Significant changes in relative frequency of health care-associated pathogens by infection site occurred over the 29-year period. These findings have implications for implementation of infection prevention strategies.