The Journal of Medical Microbiology, Vol 38, Issue 2 122-128, Copyright © 1993 by Society for General Microbiology
Genetic characterisation of isolates of Listeria monocytogenes from man, animals and food
D. J. Trott, I. D. Robertson and D. J. Hampson
School of Veterinary Studies, Murdoch University, Western Australia.
Multilocus enzyme electrophoresis was used to assess genetic relationships
between 95 isolates of Listeria monocytogenes, most of which were isolated
in Australia and New Zealand from man, animals and food. The isolates were
separable into two major genetic divisions; the majority of those from
human patients and animals were in division I, and the majority from those
foods that were not specifically associated with human listeriosis were in
division II. Isolates in division I were virulent, whereas many isolates
from food were probably less virulent and did not pose a large threat to
human health. However, isolates from certain foods, particularly pate, were
indistinguishable from those causing disease in man, and the consumption of
these products represented a clear risk factor for infection. Isolates from
infected human patients in Australia and New Zealand belonged to the same
clone of serotype 4b that has been responsible for major epidemics in the
northern hemisphere. However, a separate clone of serotype 1/2b strains,
present in both Australia and New Zealand, was responsible for two major
outbreaks that occurred in Western Australia in 1978-80 and 1990-91.
