| Listeria welshimeri |
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Firmicutes, Class Bacilli, Order Bacillales, Family Listeriaceae, Genus Listeria, Listeria welshimeri Rocourt and Grimont 1983.
Has 2 serovars (6a,6b), with 7 somatic (O factor) antigens (III, V, VI, VII, IX, XV, XXI) and 3 flagella (H factor) antigens (A,B,C).
Historical synonyms: Genomic group 4 of L. monocytogenes.
Has 2 serovars (6a,6b), with 7 somatic (O factor) antigens (III, V, VI, VII, IX, XV, XXI) and 3 flagella (H factor) antigens (A,B,C).
Historical synonyms: Genomic group 4 of L. monocytogenes.
Gram-positive short rods or coccobacilli, 0.4-0.5 x 0.5-2.5 µm, with rounded ends.
Coccoid forms are sometimes seen in smears from liquid cultures. Usually occur
singly or in short chains, palisades or diplo. Nonspore-forming. Motile by 2-6
peritrichous flagella when cultured at 28 ºC. Expression of the structural gene for the
flagellin protein (flaA) has been shown to be temperature regulated and repressed
at 37 ºC. High-level expression is seen at 25 ºC, corresponding to the temperature
at which tumbling motility is observed.
Coccoid forms are sometimes seen in smears from liquid cultures. Usually occur
singly or in short chains, palisades or diplo. Nonspore-forming. Motile by 2-6
peritrichous flagella when cultured at 28 ºC. Expression of the structural gene for the
flagellin protein (flaA) has been shown to be temperature regulated and repressed
at 37 ºC. High-level expression is seen at 25 ºC, corresponding to the temperature
at which tumbling motility is observed.
Grow well on blood agar base, nutrient, tryptose, and tryptose soy or brain heart
infusion agars; growth is enhanced by the addition of 0.2-1% (w/v) glucose, blood
or serum.
Colonies on tryptose agar are small (1 to 2 mm diameter after 1 or 2 days of incubation at 37 ºC), smooth with a blue-green color
when they are examined with obliquely transmitted light. No beta-hemolysis. CAMP test is negative both with Rhodococcus equi and
Staphylococcus aureus.
Facultatively anaerobic. Grow at/on: pH 5.5-9.0. Can grow in peptone water plus 10% NaCl. Optimum growth temperature is 37 ºC.
Grow at 4 ºC in 5 days. Multiply rapidly in milk.
infusion agars; growth is enhanced by the addition of 0.2-1% (w/v) glucose, blood
or serum.
Colonies on tryptose agar are small (1 to 2 mm diameter after 1 or 2 days of incubation at 37 ºC), smooth with a blue-green color
when they are examined with obliquely transmitted light. No beta-hemolysis. CAMP test is negative both with Rhodococcus equi and
Staphylococcus aureus.
Facultatively anaerobic. Grow at/on: pH 5.5-9.0. Can grow in peptone water plus 10% NaCl. Optimum growth temperature is 37 ºC.
Grow at 4 ºC in 5 days. Multiply rapidly in milk.
Widely distributed in nature, found in soil, mud, sewage, vegetation, and in the feces
of animals and man. Grow in the presence of 0.025% (w/v) thallous acetate; 3.75%
(w/v) potassium thiocyanate; 0.04% (w/v) potassium tellurite or 10 µg/ml tripaflavine.
Do not grow in the presence of 0.02% (w/v) sodium azide.
It is usually sensitive to amikacin, amoxycillin, ampicillin, azlocillin, ciprofloxacin,
chloramphenicol, clindamycin coumermycin, doxycycline, enoxacin, erythromycin,
gentamicin, imipen, netilmicin, penicillin, rifampin, trimethoprim, and vancomycin.
Resistant to the cephalosporins, phosphomycin, and polymyxin.
of animals and man. Grow in the presence of 0.025% (w/v) thallous acetate; 3.75%
(w/v) potassium thiocyanate; 0.04% (w/v) potassium tellurite or 10 µg/ml tripaflavine.
Do not grow in the presence of 0.02% (w/v) sodium azide.
It is usually sensitive to amikacin, amoxycillin, ampicillin, azlocillin, ciprofloxacin,
chloramphenicol, clindamycin coumermycin, doxycycline, enoxacin, erythromycin,
gentamicin, imipen, netilmicin, penicillin, rifampin, trimethoprim, and vancomycin.
Resistant to the cephalosporins, phosphomycin, and polymyxin.
Not pathogenic for mice, other animals and man.
- Hammes W.P. and Hertel C., 2009. Genus I. Listeria Pirie 1940. In: (Eds.) P.D. Vos, G. Garrity, D. Jones, N.R. Krieg, W. Ludwig, F.
A. Rainey, K.-H. Schleifer, W.B. Whitman. Bergey’s Manual of Systematic Bacteriology, Volume 3: The Firmicutes, Springer, 244-
257. - McLauchlin J., 2005. Listeria. In: Topley & Wilson’s Microbiology & Microbial Infections, 10th Edition, Edited by Borriello S.P.,
Murray P.R. and Funke G., 953-969. - Khelef N., Lecuit M., Buchrieser C., Cabanes D., Dussurget O. and Cossart P., 2006. Listeria monocytogenes and the genus
Listeria. In: Dworkin M., Falkow S., Rosenberg E., Schleifer K.H., Stackebrandt (Editors), The Prokaryotes, A Handbook on the
Biology of Bacteria, Third Edition, Volume 4, Bacteria: Firmicutes, Cyanobacteria, Springer, Chapter 1.2.11, 404-476. - Rocourt J. and Grimont P.A.D., 1983. Listeria welshimeri sp. nov. and Listeria seeligeri sp. nov. IJSB Vol. 33, No. 4, p. 866-869.
Positive results for arylesterase activity, catalase, chymotrypsin, esculin hydrolysis, beta-glucosidase, leucine esterase, methyl-red,
acid phosphatase, phosphoamidase, Voges-Proskauer reaction, tween 80 esterase, amino acid peptidase: D-alanine & lysine; acid
production from: esculin, D-glucose, glycerol, 5-ketogluconate, lactose, melezitose, methyl alpha-D-glucoside, methyl
alpha-D-mannoside, salicin, soluble starch, sucrose, trehalose, turanose, xylitol & D-xylose.
Negative results for alpha-glucosidase, casein hydrolysis, cystine arylamidase, citrate utilization, N-acetyl-beta-glucosamidase,
gelatin hydrolysis, indole production, H2S production, lecithinase, nitrates reduction to nitrites, urea hydrolysis, oxidase, amino acid
peptidase: ornithine, glutamic acid & arginine; acid production from: L-arabinose, galactose, gluconate, glucose 1-phosphate,
glycogen, D-mannitol, melibiose, ribose & tagatose.
Variable results for starch hydrolysis, acid production from: D-lyxose & rhamnose.
acid phosphatase, phosphoamidase, Voges-Proskauer reaction, tween 80 esterase, amino acid peptidase: D-alanine & lysine; acid
production from: esculin, D-glucose, glycerol, 5-ketogluconate, lactose, melezitose, methyl alpha-D-glucoside, methyl
alpha-D-mannoside, salicin, soluble starch, sucrose, trehalose, turanose, xylitol & D-xylose.
Negative results for alpha-glucosidase, casein hydrolysis, cystine arylamidase, citrate utilization, N-acetyl-beta-glucosamidase,
gelatin hydrolysis, indole production, H2S production, lecithinase, nitrates reduction to nitrites, urea hydrolysis, oxidase, amino acid
peptidase: ornithine, glutamic acid & arginine; acid production from: L-arabinose, galactose, gluconate, glucose 1-phosphate,
glycogen, D-mannitol, melibiose, ribose & tagatose.
Variable results for starch hydrolysis, acid production from: D-lyxose & rhamnose.
(c) Costin Stoica
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