文档介绍：II. HAZARD IDENTIFICATION
II. HAZARD IDENTIFICATION
In the hazard identification, the known or potential health effects associated with L. monocytogenes
are identified by establishing the general relationship between the pathogen, its presence in foods,
and the adverse e (illness or death) associated with consumption of foods contaminated with
L. monocytogenes. While the negative health impact of a hazard must be recognized for a risk
assessment to be undertaken, the nature of the impact must be clearly defined, and specific endpoints,
or health es of interest, identified. Common endpoints are infection, disease (morbidity),
death, and chronic sequelae (long-term after-effects). This risk assessment is concerned with the
endpoints of serious illness and death.
Listeria monocytogenes
L. monocytogenes is a short ( mm in diameter by 1 to 2 mm long) gram positive, non-spore-
forming rod that is part of the lactobacilli family along with genera such as Lactobacillus and
us (Rocourt, 1999). It can be isolated from numerous species of domestic and wild
animals, as well as from soil, silage, and other environmental sources. L. monocytogenes can be
classified into a number of subtypes using several methods. The mon is based upon
recognition of antigens on the surface of the bacterium by specific antisera (Graves et al., 1999).
Thirteen of these serotypes are associated with L. monocytogenes (1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a,
4ab, 4b, 4c, 4d, 4e, 7). Some are also associated with other species of Listeria (1/2b, 4ab, 4c, 4d).
The numbers and letters refer to binations of bacterial antigens used for serotyping
(Seeliger and Hohne, 1979). Serotyping is often used as a first step to type strains in human
listeriosis, but it has relatively low discriminating pared to molecular methods such as
ribotyping or Pulse Field Gel Electrophoresis (PFGE). Ribotyping relies on separation and analysis
of specific well-conserved DNA fragments and this method is oft