Re: is there any way for harmful bacteria to get into ice cream?

Ice cream is prepared from pastuerized milk and other ingredients which
are safe. As long as no bacteria or other harmful microrganisms 
contaminate any of the ingredients after processing, then ice cream
while frozen is one of the safer commodities.

If ice cream becomes contaminated with harmful bacteria at a high enough
concentration, then illness may occur. If low numbers of bacteria are
present and the ice cream melts, then sufficient numbers of bacteria may
develop.

Ice cream is a fairly complex food containing sugar, emulsifiers and
fats. Depending on the available water, bacterial growth could be rapid
in melted ice cream. If melted ice cream were contaminated and allowed
to remain at elevated temperatures, freezing temperatures later would
not make the product safe. It would be recommended not to refreeze ice
cream that had melted at room temperature. If melting took place under
refrigeration, ice cream could be safely re frozen if done so within
four days.

The bacteria most frequently identified in outbreaks are: salmonella
enteritids ( cross contamination by eggs ) and listeria momcytogenes, an
environmental contaminant.

Roy E Costa RS MS