title: Analysis of clinical and food-borne isolates of Listeria monocytogenes in the United States by multilocus enzyme electrophoresis and application of the method to epidemiologic investigations.
abstract: To investigate the microbiology and epidemiology of the 1,700 sporadic cases of listeriosis that occur annually in the United States, we developed a multilocus enzyme electrophoresis (MEE) typing system for Listeria monocytogenes. We studied 390 isolates by MEE. Eighty-two electrophoretic types (ETs) were defined. Two distinct clusters of ETs, ET group A (ETGA) and ET group B (ETGB), separated at a genetic distance of 0.440, were identified. Strains of ETGB were associated with perinatal listeriosis (P = 0.03). All strains of H antigen type a were in ETGA, while all strains of H antigen type b were in ETGB. Among 328 clinical isolates from cases of literiosis, 55 ETs of L. monocytogenes were defined. Thirty-four ETs were identified among 62 isolates from food products. The mean number of strains per ET (5.2) was significantly higher among clinical isolates than among food-borne isolates. Examination of isolates from outbreaks further documented the link between cases and contaminated food products. In one investigation, we found 11 different ETs, ruling out a single common source as a cause of that outbreak. By examining a large number of isolates collected over a specified time in diverse geographic locations in the United States, we have begun to establish a baseline for the study of the epidemiology of listeriosis by MEE.
authors.affiliation: Meningitis and Special Pathogens Branch, Centers for Disease Control, Atlanta, Georgia 30333.
authors.forename: W F
authors.initials: WF
authors.lastname: Bibb
authors.forename: B G
authors.initials: BG
authors.lastname: Gellin
authors.forename: R
authors.initials: R
authors.lastname: Weaver
authors.forename: B
authors.initials: B
authors.lastname: Schwartz
authors.forename: B D
authors.initials: BD
authors.lastname: Plikaytis
authors.forename: M W
authors.initials: MW
authors.lastname: Reeves
authors.forename: R W
authors.initials: RW
authors.lastname: Pinner
authors.forename: C V
authors.initials: CV
authors.lastname: Broome
mesh_terms: D015373:Bacterial Typing Techniques; D004196:Disease Outbreaks; D004586:Electrophoresis; D004798:Enzymes / Q000235:genetics / Q000302:isolation & purification; D004812:Epidemiologic Methods; D005516:Food Microbiology; D014644:Genetic Variation; D006801:Humans; D008089:Listeria monocytogenes / Q000145:classification / Q000201:enzymology / Q000302:isolation & purification*; D008088:Listeriosis / Q000453:epidemiology / Q000382:microbiology*; D012703:Serotyping; D014481:United States / Q000453:epidemiology
chemical_list: D004798:Enzymes