Assessment of the virulence of Listeria monocytogenes: agreement between a plaque-forming assay with HT-29 cells and infection of immunocompetent mice.
Int J Food Microbiol
; 68(1-2): 33-44, 2001 Aug 15.
Article
en En
| MEDLINE
| ID: mdl-11545218
ABSTRACT
Some Listeria monocytogenes strains not related to clinical cases have been found to exhibit a low virulence level in mice as well as in an in vitro test using Caco-2 cells. The purpose of this study was to validate a new in vitro test of virulence based on a plaque-forming assay (PFA) using a HT-29 cell monolayer with 118 Listeria strains. The use of HT-29 cells in 96-well tissue culture plates allowed the testing of 30 strains per day and providing results in 24 h. In addition. statistical analyses demonstrated the reproducibility and repeatability of the PFA. No quantitative relationship was observed between the virulence of the strains and the hemolytic titer or the cytotoxic effects on HT-29 cells. In contrast, good agreement was observed between virulence assessed after subcutaneous (SC) infection and virulence obtained by PFA. Three groups of L. monocytogenes strains (avirulent, hypovirulent and fully virulent) were established by comparison of the clinical origin of the strains, the number of immunocompetent contaminated mice and the numbers of Listeria strains recovered in the spleen after SC infection. With one exception, i.e. a clinical case of L. seeligeri (sensitivity 0.98), the PFA successfully detected the virulent strains only (specificity 1). Decision-tree algorithms performed by SAS and S-Plus demonstrated that this tissue culture assay discriminated between the avirulent and hypovirulent strains and the virulent strains. This test could therefore be an alternative to in vivo tests, allowing grading of virulence.
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Banco de datos:
MEDLINE
Asunto principal:
Virulencia
/
Huésped Inmunocomprometido
/
Listeriosis
/
Listeria monocytogenes
Tipo de estudio:
Diagnostic_studies
/
Prognostic_studies
Límite:
Animals
/
Female
/
Humans
/
Male
Idioma:
En
Revista:
Int J Food Microbiol
Asunto de la revista:
CIENCIAS DA NUTRICAO
/
MICROBIOLOGIA
Año:
2001
Tipo del documento:
Article
País de afiliación:
Francia