|Categories:||Zoonotic; causes hemolysis; motile; notifiable diseases and bacteria|
|Etymology:||Genus name: named after the British surgeon Lord Lister. |
Species epithet: monocyte producing.
|Type Strain:||ATCC 15313 = NCTC 10357.|
||Small (0,5- 1 mm in diameter) colonies, which can be crateriform on certain selective media. Produces a zone of hemolysis on blood agar.|
|Micromorphology:||Long thin rods (0.4-0.5 x 0.5-2 µm) in short chains. Motile by means of a few peritrichous flagella. L. monocytogenes also exhibits actin-based motility (see references 154 and 155 below).|
|Gram +/Gram -:||G+|
|Other Enzymes:||Esculinase +, lecithinase +, β-D-glucosidase +, hippuricase +, tryptophanase -, urease -.|
|Biochemical Tests:||Methyl red +, Voges-Proskauer +.|
|Fermentation of carbohydrates:||
|Spec. Char.:||Psychrotrophic. Can grow at 0-42°C and has temperature optimum at 30°C. Can survive at high NaCl concentrations.|
||Colonies of Listeria sp. are blue-greenish on Brillians-Listeria-agar medium because they produce a β-glucosidase. There is also a precipitate around colonies of L. monocytogenes and pathogenic strains of L. ivanovii because they have a lecithinase (see the legend to the figure).|
|Disease:||Listeriosis. Encephalitis, abortion, septicemia and eye infections (ruminants). Food poisoining and abortion (humans).
|Virulence Factors:||The membrane protein internalin, which induces cellular uptake of bacteria by phagocytosis. Listeriolysin O (a hemolysin), which makes it possible for the bacteria to escape from the phagosome before it fuses with a lysosome. The bacteria can polymerise actin by means of the protein Act A, which contributes to their intracellular mobility.|
|16S rRNA Seq.:|
||There are 21 species and subspecies described within the genus and all are very similar. L. monocytogenes and the nonpatogenic L. innocua have almost identical 16S rRNA sequences.|
|Legislation:||Listeriosis is zoonotic and a notifiable disease in Sweden. L. monocytogenes is classified as a potential biological weapon with the NIAID priority code B.|
|Comment:||Can invade cells and is facultatively intracellular (in monocytes).|
|Reference(s):||No. 31, 65, 154, 155|
|New names of taxa within the classification category phylum|
During October 2021, an article was published by A. Oren och G.M. Garrity, in which new names are proposed for a number of taxa within the classification category phylum. This has resulted in many discussions in social media about whether it was really necessary to make these changes, which have created confusion among microbiologists and other professionals who come into contact with bacteriology.Published 2022-09-28. Read more...