Friday, July 8, 2011

Botulism and Potato Soup - CDC Report 7/8/11

In two separate cases this year as reported by CDC,  individuals became ill with botulism following consumption of improperly stored potato soup.  In each case, refrigerated RTE potato soup was purchased from retail and then tasted by the consumer after prolonged storage at room temperature (even though the label stated Store in Refrigerator). 

A few interesting notes:
1)    It is becoming more common for retailers as well as manufacturers to make refrigerated RTE products with no secondary hurdles (preservatives) to prevent Clostridium botulinum growth. So thus refrigeration is the only control factor. This creates a huge risk with regard to temperature abuse….spores of Clostridium, surviving the heat treatment used in making soup, will grow if the product is stored at temperatures greater than 50ºF to 54ºF. (for Proteolytic strains such as Type A.  Non-proteolytic strains can grow as low as 38F, but have less heat resistance so would not survive the initial boil when making soup).

2)    Both persons suffered severe illness for weeks even though they just tasted the soup, a testament of the toxicity.  Botulinum toxin is regarded as one of the most potent toxins known to man. (If they had hard boiled the soup for ~10 min before consuming, it would have inactivated the toxin, and although it would have tasted bad, it would probably not have caused botulism)

3)    Consumers do crazy things – First, refrigerated product was stored at room temperature for a long time, and two, even though it smelled bad and was swollen, they still tried it.  Reminds me of an old Cheech and Chong skit.

Notes from the Field: Botulism Caused by Consumption of Commercially Produced Potato Soups Stored Improperly --- Ohio and Georgia, 2011
July 8, 2011 / 60(26);890
In January and April 2011, CDC provided antitoxin for treatment of two persons with toxin type A botulism associated with consumption of potato soup produced by two companies. On January 28, 2011, an Ohio resident, aged 29 years, was hospitalized after 5 days of progressive dizziness, blurred vision, dysphagia, and difficulty breathing. The patient required mechanical ventilation and botulism antitoxin. On January 18, he had tasted potato soup from a bulging plastic container, noted a bad taste, and discarded the remainder. The soup had been purchased on December 7, 2010, from the refrigerated section of a local grocer, but it had been kept unrefrigerated for 42 days. He was hospitalized for 57 days and then was transferred with residual weakness to a rehabilitation facility.
On April 8, 2011, a Georgia resident, aged 41 years, was hospitalized after 4 days of progressive dizziness and dysphagia. The patient developed respiratory distress, required mechanical ventilation, and was treated with botulism antitoxin. On April 3, she had tasted potato soup purchased from a local grocer, noted a sour taste, and discarded the remainder. The soup, stored in a plastic container labeled "keep refrigerated" in letters 1/8 inch tall, had been purchased on March 16, but had been left unrefrigerated for 18 days. She was hospitalized for 16 days and then was transferred with residual weakness to a rehabilitation facility.
Botulism is caused by a paralyzing toxin produced by Clostridium botulinum bacteria. C. botulinum spores are present in soil and can be found on raw produce, especially potatoes and other root vegetables (1). If a low-acid food such as potato soup is stored unrefrigerated in an anaerobic environment (e.g., a sealed container), without a barrier to bacterial growth, spores can germinate, resulting in bacterial growth and botulinum toxin production (2). Because heating food to a temperature of 185°F (85°C) for 5 minutes inactivates the toxin, proper preparation also is an important safeguard (3).
Improper storage has been documented in previous botulism outbreaks associated with commercially produced, chilled foods. Since 1975, 19 U.S. botulism cases were linked to six such products. Demand for prepared, chilled foods is increasing (4). Labels advising refrigeration might be ignored or not noticed, and do not warn about the danger of consuming unrefrigerated food. The Food and Drug Administration is reexamining labeling requirements. Storage at an improper temperature also can occur before products reach consumers (5). To inhibit the growth of C. botulinum and other microbes, an acidifying agent or other microbial inhibitor, such as citric or phosphoric acid, can be added to prepared, chilled foods before they are sealed in a package. This procedure was used successfully to reduce the danger of botulism from commercial garlic-in-oil products after two outbreaks (6).
Reported by
Mandy P. Seaman, Alana C. Sulka, Gwinnett County, Georgia Board of Health. Melissa Tobin D'Angelo, Georgia Dept of Community Health. Mitchell A. Blass, St. Joseph's Hospital, Atlanta, Georgia. Randy L. Mills, Ohio State Univ Hospitals East, Columbus; Jane Carmean, Ohio Dept of Health. Carolina Lúquez, Susan Maslanka, Kelly A. Jackson, Barbara E. Mahon, Patricia M. Griffin, Div of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases; Katherine A. O'Connor, Ethel V. Taylor, EIS officers, CDC. Corresponding contributor: Katherine A. O'Connor,, 404-639-0195.
  1. Angulo FJ, Getz J, Taylor JP, et al. A large outbreak of botulism: the hazardous baked potato. J Infect Dis 1998;178:172--7.
  2. Sheth AN, Wiersma P, Atrubin D, et al. International outbreak of severe botulism with prolonged toxemia caused by commercial carrot juice. Clin Infect Dis 2008;47:1245--51.
  3. Sobel J. Botulism. Clin Infect Dis 2005;41:1167--73.
  4. Peck MW. Clostridium botulinum and the safety of minimally heated, chilled foods: an emerging issue? J Appl Microbiol 2006;101:556--70.
  5. Kalluri P, Crowe C, Reller M, et al. An outbreak of foodborne botulism associated with food sold at a salvage store in Texas. Clin Infect Dis 2003;37:1490--5.
  6. Morse DL, Pickard LK, Guzewich JJ, Devine BD, Shayegani M. Garlic-in-oil associated botulism: episode leads to product modification. Am J Public Health 1990;80:1372--3.

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