The possibility that E. coli O157:H7 was a contaminant in cookie dough surprised even the most experienced microbiologists here in CDC’s Enteric Diseases Laboratory Branch. E. coli O157 is a common culprit of a severe diarrheal illness, usually caused by eating contaminated and undercooked ground beef or drinking unpasteurized apple juice. It shouldn’t have even been on the “Who’s Who” list of the top bacterial contaminants.

The road to last month’s cookie dough recall started when CDC scientists reviewed information collected through PulseNet, a national network of laboratories that perform DNA “fingerprinting” of foodborne bacteria like E. coli O157:H7, Salmonella, and Listeria. These fingerprints are plugged into a database that CDC and its state partners routinely scan. I’m a PulseNet database manager at CDC and one of my jobs is to identify “clusters” - groups of illnesses that share the same fingerprint.

Under a very high magnification of 12000X, this colorized scanning electron micrograph (SEM) revealed the presence of a large grouping of Gram-negative Salmonella Typhimurium bacteria that had been isolated from a pure culture.

Foodborne illnesses occur throughout the year and summers tend to be busy with outbreaks. I work in CDC’s Enteric Diseases Epidemiology Branch and we just spent a few busy weeks on an investigation linking E. coli 0157 illnesses to raw cookie dough. See Karen Neil’s blog about that process.

Still, even in our busiest times, we don’t generally find ourselves spending entire weekends working on outbreaks. But on Saturday and Sunday, March 28 and 29, 2009, our branch found itself tracking the investigations of seven Salmonella outbreaks concurrently – six in the United States and one in Uganda. I was Acting OutbreakNet Team Lead that weekend.

Contaminated raw cookie dough wasn’t on anyone’s mind as my public health colleagues and I were searching for the cause of a multistate outbreak of E. coli infections.

I’m one of the Epidemic Intelligence Service officers in CDC’s Enteric Diseases Epidemiology Branch, which monitors and investigates foodborne diseases together with CDC’s Enteric Disease Laboratory Branch and state health departments. On any given day we are working on several clusters and outbreaks of illness.

The media has recently given attention to studies [G. Songer; Rodriguez-Palacios A, et al] that isolated a bacterium called Clostridium difficile from meats sold in grocery stores.  C. difficile causes a severe colon infection and is generally acquired in hospitals and long-term care facilities.  Although most of the cases of C. difficile infection are healthcare associated (80%), the other twenty percent of cases are acquired in the community - outside of healthcare settings.  The cause(s) of these infections are still poorly understood.  The recent studies question whether C. difficile in meats is a source of human infection.

CDC plays a vital role but public health happens at the local level thanks to the work of thousands of our state, territorial, tribal, city, and county public health professionals. So it is always a pleasure to meet with state epidemiologists, leaders in using epidemiologic data to guide public health practice and improve health.  On January 29th, I met with the Executive Board of the Council of State and Territorial Epidemiologists [CSTE]. Needless to say, the conversation quickly strayed to the current Salmonella Typhimurium outbreak associated with peanut butter produced at a Peanut Corporation of America (PCA) facility in Blakely, Georgia. These conversations among colleagues are noteworthy for being quite frank.