[Straight Vermonter]

Listeria monocytogenes is very unusual in that it's growth is enhanced by cold temperatures.

No. It grows best at ~37C. The closer to that temp the better it grows.

Like all bacteria it's growth is retarded by cold temperatures. It is, however, more resistant to cold than many other pathogens. It will grow in normal refrigeration temps and can survive even deep freezing.

[srmorton]

I said in my post that its growth is enhanced by cold temperatures and that is absolutely true! I am a former Medical Technologist and have been teaching Clinical Microbiology to Medical Laboratory Technicians for over 30 years. The "cold enrichment" technique was used in the past to encourage the growth of the organism. The placenta or other tissues from babies who were stillborn due to transmission of the organism from mother to child were placed in the refrigerator at four degrees for several weeks to try to recover the organism.

It does grow well at 37 degrees. I keep a culture in my lab for my students and I sub it every week. It will grow well overnight in a 37 degree incubator on Sheep Blood Agar. It does grow much more slowly in the cold, but the point of my post is that any other bacteria I can think of (except maybe Yersinea) would not be able to multiply enough at such cold temperatures to cause an infection, whereas Listeria is the most common cause of food infections in which refrigerated or frozen food is the source.