of the most important limitations for the isolation of pathogenic
bacteria from foods is their low concentration (commonly less than
100 cells per gram) and the high levels of background microbiota.
To overcome these limitations, conventional methods for the
detection of L. monocytogenes in foods including those recom-
mended by the US Food and Drug Administration (Hitchins and
Jinneman, 2011) and the US Department of Agriculture (USDA,
2013) consist of one or more enrichment steps followed by isola-
tion on selective media.
The Modified Oxford agar (MOX) is a medium commonly used in
the selective isolation of listeriae on the basis of the hydrolysis of
esculin, which contributes to the differentiation of the listeriae
from other bacteria. Although this medium has been found efficient
for the isolation of listeriae from food products, some components
of the selective supplements added to this medium, such as colistin
methane sulfonate and sodium moxalactam may be difficult to
obtain in developing countries, due in part to the costs of import