Listeria in California Onions

This article by Jerry Cates, first published on 30 July 2012, was last revised on 9 August 2012. © Bugsinthenews Vol. 13:07(01).


On 18 July Gills Onions LLC, a multi-generational family-run onion processing firm founded in 1983 in Oxnard, California, issued a voluntary recall of the onions shipped between July 2-4 due to the possibility that they had been contaminated by a serious human pathogen, the bacteria Listeria monocytogenes. On 26 July 26, after Listeria was found in the processing facility involved in the earlier recall, the recall was expanded to include processed onions and onion and celery mixes with use-by dates on or before 3 August.

These products had been shipped to local outlets in California, as well as to Canada (Alberta, British Columbia, and Ontario) and a variety of out-of-state U.S. outlets in Arizona, Colorado, Illinois, Montana, New York, Oklahoma, Oregon, Pennsylvania, Texas, Utah and Washington. Included in the recall were

-A number of foods prepared for Whole Foods Market outlets in Florida;

-Salsa, balela, and barbecue chicken salad sold by Trader Joe’s in the states of Florida, Georgia, North Carolina, South Carolina, Tennessee and southern Virginia;

-Bean dips and salsas sold by Cool Creations, LLC in Arkansas, Iowa, Kansas, Missouri and Oklahoma;

-A number of prepared foods sold by Wegmans at three Syracuse NY stores; and

-A variety of food products sold by GH Foods CA, LLC in California, Arizona, Nevada and Utah.

Listeria is capable of producing serious, even fatal infections in children, the elderly and those suffering from compromised immune systems; in such individuals the infection often leads to meningitis and similar conditions, all of which pose severe risks to the victim. In general, adults in good health with intact immune systems, who become infected with listeria, report nothing worse than high fevers, severe headaches, stiffness, nausea, abdominal pain, and diarrhea. No illnesses have been linked, at present (30 July 2012) to the listeria-contaminated onions involved in this recall.



  • Kingdom Bacteria: Once considered plants, but now classified within the large domain of prokaryotic microorganisms. The term prokaryote combines the Greek πρό- (pro-) “before” + καρυόν (karyon) “nut or kernel” and refers to an organism that does not have a nucleus. Typically micrometres in length, bacteria exhibit a variety of shapes, including spheres, rods, and spirals. Besides absent a nucleus, bacteria rarely possess membrane-bound organelles;
  • Division Firmicutes: The division name is derived from the Latin adjective firmus = strong, and the Latin noun cutis = skin, a reference to the presence of a cell wall. Most have Gram-positive cell wall structures, though the Megasphaera, Pectinatus, Selenomonas and Zymophilus, have porous pseudo-outer-membranes that stain Gram-negative. The organisms in this division appear as spherical cocci or rod-like bacilli under the microscope;
  • Class Bacilli: a taxonomic class of bacteria that includes the two orders Bacillales and Lactobacillales; these contain several virulent pathogens like Bacillus anthracis (the cause of anthrax), along with a number of non-pathogenic, highly beneficial organisms used in the fermentation of milk into cheese, yogurt, and similar products;
  • Order Bacillales: an order of Gram-positive organisms, within the division Firmicutes and the class Bacilli, including the bacteria families Alicyclobacillaceae, Bacillaceae, Caryophanaceae, Listeriaceae, Paenibacillaceae, Planococcaceae, Sporolactobacillaceae, Staphylococcaceae, Thermoactinomycetaceae, and Turicibacteraceae;
  • Family Listeriaceae (Garrity et al. 2001): a family of Gram-positive bacteria first described in 2001 by Garrity et al. and comprised to two genera, Brochothrix and Listeria;
  • Genus Listeria (Pirie 1940):  a genus of bacteria comprised of seven recognized species: L. grayi, L. innocua, L. ivanovii, L. monocytogenes, L. seeligeri, L. murrayi, and L. welshimeri;
  • Species Listeria monocytogenes [(E. Murray et al. 1926) Pirie 1940]: a facultative anaerobic intracellular bacterium known to cause the disease listeriosis, a virulent foodborne infection that, 20% to 30% of the time, results in death. Listeriosis is responsible, each year, for approximately 2,500 illnesses and 500 deaths in the United States. It is the leading cause of death among foodborne bacterial pathogens, with fatality rates exceeding those of Salmonella and Clostridium botulinum. L. monocytogenes is motile via flagella at 30°C and below, but usually not at 37°C (normal human body temperature). At and above 37°C L. monocytogenes moves within eukaryotic cells by explosive polymerization of actin filaments. As much as 10% of human gastrointestinal tracts are endemically colonized by L. monocytogenes without producing clinical symptoms in those individuals, but because it is the third most common cause of meningitis in newborns (the bacteria are typically acquired transvaginally) pregnant mothers who enjoy soft cheeses such as Brie, Camembert, feta, and queso blanco fresco — which may be contaminated with and permit growth of L. monocytogenes — are advised to forgo such foods while pregnant.




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