Variations in virulence between different electrophoretic types of Listeria monocytogenes

Birgit Nørrung, Jens Kirk Andersen

Research output: Contribution to journalJournal articleResearchpeer-review


A total of 245 strains of Listeria monocytogenes, representing 33 different electrophoretic types (ETs), were examined quantitatively for haemolytic activity. No significant difference was observed in the mean haemolytic activity between different ETs. Eighty four out of 91 strains examined were found to be virulent for chick embryos. Strains belonging to ET 2 and ET 4 were found to be less virulent than strains of other ETs (P = 0.0447). Furthermore, strains from clinical cases were found to be more virulent (P = 0.0002) than strains from foods (the MTD among clinical strains was 2.46 in mean compared with 3.64 among food isolates). The explanation for this may be that more virulent strains are more prone to cause human infection. It is, however, also possible that strains oft. monocytogenes may become more virulent while multiplying in a living organism compared with multiplying in foods.
Original languageEnglish
JournalLetters in Applied Microbiology
Issue number3
Pages (from-to)228-232
Publication statusPublished - 2000


Dive into the research topics of 'Variations in virulence between different electrophoretic types of Listeria monocytogenes'. Together they form a unique fingerprint.

Cite this