C H A P T E R I 1
Serotyping of Listeria monocytogenes
and Related Species
H. P. R. SEELIGER and K. HOHNE
University of Wiirzburg, Federal Republic of Germany
I. Morphology and Structure
.
. 31
11. Chemical Composition
.
. 32
111. Isolation Procedures; Cultural and Biochemical Identification .
. 33
A. Isolation from infected material
.
. 33
B. Biochemical properties .
. 35
C. The CAMP phenomenon in Listeria .
. 37
IV. Antigenic Structure and Serological Identification
.
. 39
A. Historical development .
. 39
B. Methods for preparation of Listeria antigens
.
. 40
C. Production of antisera
.
. 41
D. Production of factor sera .
. 42
E. Conservation of factor sera
.
. 4 4
F. Results of serological analysis .
. 4 4
G. Cross-reactions
.
. 47
References
.
. 48
I. MORPHOLOGY AND STRUCTURE
Listeria monocytogenes is a short, Gram-positive, non-acid fast rod
without spores. Young cultures consist predominantly of coccoid organisms measuring 0.5 by 1-2 pm. Their ends often appear slightly pointed.
The arrangement of cells in smears is quite uncharacteristic. Besides
single organisms and pairs, one finds short chains of 3-8 cells and diploforms which are sometimes V- or Y-shaped. Occasionally slender, slightly
curved rods, 2-5 p m in length are seen. Club shaped organisms or pleomorphic involution forms have not been observed.
In cultures incubated for 3-6 h at 37"C, the bacillary forms prevail.
Thereafter most organisms become coccoid. In older cultures, i.e. after
3-5 days' incubation, filamentous structures often appear, mainly in rough
strains. They measure from 6 to 20 p m in length, filaments up to 275 p m
have occasionally been observed. By use of immunocytological methods and