Retrospective analysis of plasmid patterns in a study of burn unit outbreaks of infection due to Enterobacter cloacae

J Infect Dis. 1983 Jul;148(1):18-23. doi: 10.1093/infdis/148.1.18.


To evaluate the usefulness of plasmid pattern analysis as an epidemiologic tool and to determine the mechanism of resistance to silver sulfadiazine and mafenide acetate, silver sulfadiazine-resistant, mafenide acetate-resistant Enterobacter cloacae isolates from a 1976 outbreak of infections in a burn unit (group I) were analyzed retrospectively. These strains were compared with various E cloacae isolates (groups II-V), including E cloacae isolates from a more recent (1982) burn unit outbreak (group V). Agarose gel electrophoresis (AGE) of DNA isolated from "epidemic" strains of E cloacae revealed a uniform pattern of four plasmid DNA bands, ranging in molecular size from 66 to 2 megadaltons. No such plasmid pattern was seen in silver sulfadiazine-, mafenide acetate-susceptible isolates of E cloacae in groups II, III, and V. Analysis of non-E cloacae coisolates suggested that silver sulfadiazine resistance was associated with the 55-megadalton plasmid. Plasmid pattern analysis easily separated "epidemic" E cloacae isolated in 1976 from those isolated in 1982.

MeSH terms

  • Burns / complications
  • Burns / microbiology*
  • Disease Outbreaks / epidemiology*
  • Drug Resistance, Microbial
  • Electrophoresis, Agar Gel
  • Enterobacter / genetics
  • Enterobacter / isolation & purification
  • Enterobacteriaceae Infections / complications
  • Enterobacteriaceae Infections / epidemiology
  • Enterobacteriaceae Infections / microbiology*
  • Humans
  • Plasmids / drug effects*
  • Retrospective Studies
  • Sepsis / etiology
  • Sepsis / microbiology
  • Virginia
  • Wound Infection / etiology
  • Wound Infection / microbiology