title: Methicillin-resistant Staphylococcus aureus in U.S. hospitals, 1975-1991.
abstract: OBJECTIVE
  Analyze changes that have occurred among U.S. hospitals over a 17-year period, 1975 through 1991, in the percentage of Staphylococcus aureus resistant to beta-lactam antibiotics and associated with nosocomial infections.
  
  
  METHODS
  Retrospective review. The percentage of methicillin-resistant S aureus (MRSA) was defined as the number of S aureus isolates resistant to either methicillin, oxacillin, or nafcillin divided by the total number of S aureus isolates for which methicillin, oxacillin, or nafcillin susceptibility test results were reported to the National Nosocomial Infections Surveillance (NNIS) System.
  
  
  METHODS
  NNIS System hospitals.
  
  
  RESULTS
  Of the 66,132 S aureus isolates that were tested for susceptibility to methicillin, oxacillin, or nafcillin during 1975 through 1991, 6,986 (11%) were resistant to methicillin, oxacillin, or nafcillin. The percentage MRSA among all hospitals rose from 2.4% in 1975 to 29% in 1991, but the rate of increase differed significantly among 3 bed-size categories: < 200 beds, 200 to 499 beds, and > or = 500 beds. In 1991, for hospitals with < 200 beds, 14.9% of S aureus isolates were MRSA; for hospitals with 200 to 499 beds, 20.3% were MRSA; and for hospitals with > or = 500 beds, 38.3% were MRSA. The percentage MRSA in each of the bed-size categories rose above 5% at different times: in 1983, for hospitals with > or = 500 beds; in 1985, for hospitals with 200 to 499 beds; and in 1987, for hospitals with < 200 beds.
  
  
  CONCLUSIONS
  This study suggests that hospitals of all sizes are facing the problem of MRSA, the problem appears to be increasing regardless of hospital size, and control measures advocated for MRSA appear to require re-evaluation. Further study of MRSA in hospitals would benefit our understanding of this costly pathogen.
authors: Hospital Infections Program, National Center for Infectious Diseases, Centers for Disease Control, Atlanta, GA 30333.
authors: A L
authors: AL
authors: Panlilio
authors: D H
authors: DH
authors: Culver
authors: R P
authors: RP
authors: Gaynes
authors: S
authors: S
authors: Banerjee
authors: T S
authors: TS
authors: Henderson
authors: J S
authors: JS
authors: Tolson
authors: W J
authors: WJ
authors: Martone
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology*; D006742:Hospital Bed Capacity; D006761:Hospitals / Q000145:classification / Q000706:statistics & numerical data* / Q000639:trends; D006801:Humans; D007769:Lactams; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D014481:United States / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D007769:Lactams