Analysis of Listeria monocytogenes by multilocus enzyme electrophoresis and application of the method to epidemiologic investigations

Int J Food Microbiol. 1989 Jun;8(3):233-9. doi: 10.1016/0168-1605(89)90018-4.


We examined 310 strains of Listeria monocytogenes by multilocus enzyme electrophoresis. Fifty-six electrophoretic types (ETs) of the organism were defined: 10 for serovar 4b strains, 11 for serovar 1/2b strains, and 30 for serovar 1/2a strains. Strains of serovars 1/2c, 3a, and 3b, and a non-typable strain were distributed among the remaining five ETs. The mean genetic diversity of the species was 0.41. Principal coordinate analysis revealed a sharp division among ETs which divided the species into two major clusters. ETs containing serovar 1/2a strains were in one cluster while all ETs containing serovar 4b, 1/2b, and 3b strains were in the second cluster. Except for two ETs that contained strains from both serovar 1/2b and serovar 3b, no ET contained strains from more than one serovar. Multilocus enzyme electrophoresis facilitated the analysis of epidemiologic data. In three separate epidemiologic investigations electrophoretic typing confirmed a common source as a cause of an outbreak; in a fourth investigation a single common source as a cause of an outbreak was effectively ruled out. Electrophoretic typing was also useful in documenting potential links between Listeria contaminated foods and persons with listeriosis who consumed those foods.

MeSH terms

  • Animals
  • Disease Outbreaks*
  • Electrophoresis, Starch Gel
  • Enzymes / analysis*
  • Food Microbiology*
  • Genetic Variation
  • Humans
  • Listeria monocytogenes / classification*
  • Listeria monocytogenes / enzymology
  • Listeria monocytogenes / genetics
  • Listeriosis / epidemiology
  • Listeriosis / microbiology*
  • Los Angeles / epidemiology
  • Massachusetts / epidemiology


  • Enzymes