L. monocytogenes was recovered from 25% of raw beef chunk
samples, and these results are in agreement with those previously
reported by others. L. monocytogenes has been isolated from 3.6 to
92.0% of raw pork retail samples (Baer et al., 2013). The high fre-
quency of L. monocytogenes isolation observed could be related to
the lack of good manufacturing practices either during carcass
dressing at slaughter establishments, or during cut fabrication at
retailing. Previous studies conducted by our research group showed
that in this area of Mexico, failure to comply with good
manufacturing practices at butcher's shops is common and favors
the cross-contamination of cuts and ground beef fabricated at these
establishments (Cabrera-Diaz et al., 2013). During raw beef sample
collection for this study, it was observed that butcher's shops em-
ployees used the same utensils to process raw pork and beef
without disinfection in between, facilitating cross contamination of
raw beef with Listeria spp. naturally present on pork.
The high frequency of isolation observed for L. monocytogenes in
fresh squeezed orange juice (26.0%) may be related to lack of hy-
giene practices during juice fabrication at the retail establishments
visited. A previous investigation published by our research group