title: Retrospective analysis of plasmid patterns in a study of burn unit outbreaks of infection due to Enterobacter cloacae.
abstract: 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: D002056:Burns / Q000150:complications / Q000382:microbiology*; D004196:Disease Outbreaks / Q000453:epidemiology*; D004352:Drug Resistance, Microbial; D004587:Electrophoresis, Agar Gel; D004754:Enterobacter / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000150:complications / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D010957:Plasmids / Q000187:drug effects*; D012189:Retrospective Studies; D018805:Sepsis / Q000209:etiology / Q000382:microbiology; D014768:Virginia; D014946:Wound Infection / Q000209:etiology / Q000382:microbiology