Predominant pathogens in hospital infections.

To determine the distribution of pathogens causing nosocomial infections in United States hospitals, we analysed data from the National Nosocomial Infections Surveillance (NNIS) System. From October 1986 to December 1990, amongst hospitals conducting hospital-wide surveillance, the five most commonly reported pathogens were Escherichia coli (13.7%), Staphylococcus aureus (11.2%), enterococci (10.7%), Pseudomonas aeruginosa (10.1%), and coagulase-negative staphylococci (9.7%). The commonest pathogens reported by site included, bloodstream: coagulase-negative staphylococci, S. aureus, enterococci, E. coli, and Candida spp.; lower respiratory tract infection: S. aureus, P. aeruginosa and Enterobacter spp.; surgical wound infection: S. aureus, enterococci and coagulase-negative staphylococci; and urinary tract infection: E. coli, enterococci, and P. aeruginosa. Among hospitals conducting intensive care unit (ICU) surveillance, the commonest pathogens were P. aeruginosa (12.4%), S. aureus (12.3%), coagulase-negative staphylococci (10.2%), Candida spp. (10.1%), Enterobacter spp. and enterococci (8.6% each). In the ICUs, the commonest pathogens found in the bloodstream were coagulase-negative staphylococci, S. aureus, and enterococci; in lower respiratory tract infections P. aeruginosa, S. aureus, and enterococci; in surgical wound infections enterococci, coagulase-negative staphylococci, and Enterobacter spp. and in urinary tract infections Candida spp., E. coli, enterococci, P. aeruginosa, and Enterobacter spp. These data show that S. aureus, E. coli and P. aeruginosa remain important nosocomial pathogens, that coagulase-negative staphylococci, enterococci and C. albicans are pathogens of increasing importance, and that the distribution of pathogens differs by site and hospital location.