Which Nosocomial Infections Are Emerging?
We have witnessed a cyclical parade of pathogens in hospitals. In Semmelweis’s era, group A streptococci created most nosocomial problems. For the next 50 to 60 years, gram-positive cocci, particularly streptococci and Staphylococcus aureus, were the hospital pathogens of major concern. These problems culminated in the pandemic of 1940 to 1950, when S. aureus phage type 94/96 caused major nosocomial problems. In the 1970s, gram-negative bacilli, particularly Pseudomonas aeruginosa and Enterobacteriaceae, became synonymous with nosocomial infection. By the late 1980s and early 1990s, several different classes of antimicrobial drugs effective against gram-negative bacilli provided a brief respite. During this time, methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE) emerged, signaling the return of the “blue bugs.” In 1990 to 1996, the three most common gram-positive pathogens S. aureus, coagulase-negative staphylococci, and enterococci accounted for 34% of
