Analysis of Listeria monocytogenes by multilocus enzyme electrophoresis and application of the method to epidemiologic investigations.
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.
Bibb
W F
WF
Division of Bacterial Diseases, Centers for Disease Control, Atlanta, GA 30333.
Schwartz
B
B
Gellin
B G
BG
Plikaytis
B D
BD
Weaver
R E
RE
D000818:Animals; D004196:Disease Outbreaks; D004592:Electrophoresis, Starch Gel; D004798:Enzymes / Q000032:analysis*; D005516:Food Microbiology; D014644:Genetic Variation; D006801:Humans; D008089:Listeria monocytogenes / Q000145:classification* / Q000201:enzymology / Q000235:genetics; D008088:Listeriosis / Q000453:epidemiology / Q000382:microbiology*; D015141:Los Angeles / Q000453:epidemiology; D008404:Massachusetts / Q000453:epidemiology
D004798:Enzymes