An improved selective medium for the isolation of Escherichia coli O157

J Med Microbiol. 1991 Aug;35(2):107-10. doi: 10.1099/00222615-35-2-107.


Sorbitol-MacConkey medium has become widely used for the isolation of verotoxigenic (VT+) Escherichia coli O157. However, many organisms other than VT+ E. coli O157, especially other serogroups of E. coli and Proteus spp., may not ferment sorbitol, and thus may be confused initially with VT+ E. coli O157. Rhamnose is not fermented by VT+ E. coli O157, but is by most sorbitol non-fermenting E. coli of other serogroups. Cefixime is a cephalosporin antibiotic that is more active against Proteus spp. than against E. coli. Inclusion of rhamnose and cefixime in sorbitol-MacConkey agar improves its selectivity for the isolation of VT+ E. coli O157.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Infective Agents, Urinary / pharmacology
  • Bacterial Toxins
  • Cefixime
  • Cefotaxime / analogs & derivatives
  • Cefotaxime / pharmacology
  • Culture Media* / pharmacology
  • Diarrhea / microbiology
  • Escherichia coli / drug effects
  • Escherichia coli / isolation & purification*
  • Escherichia coli Infections / diagnosis
  • Escherichia coli Infections / microbiology
  • Feces / microbiology
  • Microbial Sensitivity Tests
  • Rhamnose / pharmacology
  • Shiga Toxin 1


  • Anti-Infective Agents, Urinary
  • Bacterial Toxins
  • Culture Media
  • Shiga Toxin 1
  • Cefixime
  • Cefotaxime
  • Rhamnose