RESUMO
The infectivities of 66 Listeria monocytogenes isolates were assessed by intragastric inoculation of mice. Eight were poorly infective. Serovars 4b and 1/2 were more infective than serovars 3 and 4nonb. A noninfective isolate was cleared more rapidly from the cecum than were infective isolates, suggesting that survival in the gut may relate to infectivity.
Assuntos
Listeria monocytogenes/patogenicidade , Animais , Sistema Digestório , Variação Genética , Injeções , Listeria monocytogenes/crescimento & desenvolvimento , Listeria monocytogenes/isolamento & purificação , Camundongos , Camundongos Endogâmicos BALB CRESUMO
The infectivity of 19 haemolytic isolates of Listeria monocytogenes from different sources (clinical and environmental) and representative isolates from Listeria ivanovii and Listeria innocua was compared following intragastric (i.g.) and intravenous (i.v.) inoculation in immunocompetent male BALB/c mice. There was marked variation in the infectivity of the different isolates by either route but when isolates were ranked in descending order by spleen count, following i.g. administration, the strains fell into four groups. Infectivity of some isolates also differed when i.v. inoculation was compared with i.g. administration, so that assessment of virulence by spleen counts only following i.v. inoculation might fail to detect isolates of poor infectivity by the i.g. route. These results suggest that intragastric inoculation of normal immunocompetent mice is a useful model for detecting strains of L. monocytogenes that are poorly invasive via the gut even though they are relatively virulent by intravenous inoculation.
