Peanut Butter–Associated Salmonellosis Outbreak

One of the most popular food staples for children and adults, peanut butter has been banned from many schools and institutions because of its propensity for causing severe allergic reactions. Now, another peanut-related problem has arisen: salmonellosis. Peanut butter and peanut paste processed by a company in Georgia and contaminated with Salmonella serotype Typhimurium have been implicated in an outbreak that, as of January 28, 2009, had involved at least 530 people, required 116 hospitalizations, and possibly caused eight deaths.

CDC epidemiologists determined that a single strain of S. Typhimurium, identified by an unusual pulsed-field gel electrophoresis pattern, was responsible for all cases from which isolates were available. Illness appeared to have started in September 2008. Case-control studies indicated that peanut butter and specific brands of prepackaged peanut butter crackers (matched odds ratios, 2.53 and 12.25, respectively) were the source of S. Typhimurium; further investigation traced the implicated ingredients to a peanut-processing plant in Georgia. Many of the patients interviewed also reported having eaten chicken (often the source of S. Typhimurium), but chicken consumption was equally common in the general public.

Of note, testing of a recently manufactured but previously unopened jar of peanut butter from the same processor yielded a different organism, Salmonella serotype Tennessee. This organism was responsible for the only other peanut butter–associated salmonellosis outbreak in the U.S., in 2006–2007. The current outbreak continues, with lower case-incidence.