Eventual Management of Sprout Transmitted Salmonellosis

Eventual Management of Sprout-Transmitted Salmonellosis

Journal of Clinical Microbiology, August 2002, p. 3109, Vol. 40, No. 8

Corry B. Struijk*
D. A. A. Mossel*
Eijkman Foundation, Utrecht University, P.O. Box 6024, 3503 PA Utrecht, The Netherlands

Letter to the Editor 
We have read the contribution of Proctor et al. (10) with great interest. It illustrates most explicitly that food products of vegetable origin may be associated with outbreaks of salmonellosis with an attack rate of the order of 104, until recently consideredto be due mainly to products of animal origin. The finding that decontamination of seeds (1) does not preclude the possibility that sprouts will become a vehicle for pathogenic Enterobacteriaceaeis not surprising. A sporadic cell, stemming from the entericallycontaminated environment and protected by minor cracks (2), may survive exposure to a disinfectant. During sprouting this will colonize the produce, which constitutes an excellent niche for microbial proliferation because it is free of antimicrobial constituents and provides high humidity and permissive temperatures (4, 7).  

Avoiding exposure, particularly of the young, old, pregnant, and immunocompromised segment of the public (9), to contaminated sprouts can, however, be addressed by an option other than shunning ingestion. In the 1930s the nestor of British infectiologists, Sir Graham Wilson, advocated a strategy of protection of the population from food-transmitted pathogens termed Wilson's triad (8). Where preventive measures, such as good agricultural practices in the instance of sprouts, fail, terminal decontamination (pathogen reduction) offers an effective complementary mode of intervention; milk pasteurization constitutes the classical example of this scenario.

Our previous general experience (5), recently substantiated for sprouts (11), demonstrates that treatment of sprouts with gamma rays at the level of <3 kGy may be expected to ensure an adequate reduction of the initial load of pathogenic Enterobacteriaceae, provided it is linked to seed decontamination and meticulous hygiene during the sprouting phase. It appears (3) that this treatment will not markedly diminish nutritional and sensory attributes of the produce. Radiation-induced adverse health effects need not be feared (5). Opposition to this mode of processing-for-safety, rooted in perceived malignant effects of radiation per se, can be expected. This can be mitigated through emphasizing the overall public health benefits by means of communication from experts regarding safety (6).

  1. Beuchat, L. R., T. E. Ward, and C. A. Pettigrew. 2001. Comparison of chlorine and a prototype produce wash product for effectiveness in killing Salmonella and Escherichia coli O157:H7 on alfalfa seeds. J. Food Prot. 64:152-158.[Medline]
  1. Charkowski, A. O., C. Z. Sarreal, and R. E. Mandrell. 2001. Wrinkled alfalfa seeds harbor more aerobic bacteria and are more difficult to sanitize than smooth seeds. J. Food Prot. 64:1292-1298.[Medline]
  1. Fan, X., and D. W. Thayer. 2001. Quality of irradiated alfalfa sprouts. J. Food Prot. 64:1574-1578.[Medline]
  1. Jaquette, C. B., L. R. Beuchat, and B. E. Mahon. 1996. Efficacy of chlorine and heat treatment in killing Salmonella stanley inoculated onto alfalfa seeds and growth and survival of the pathogen during sprouting and storage. Appl. Environ. Microbiol. 62:2212-2215.[Abstract]
  1. Mossel, D. A. A., and H. Stegeman. 1985. Irradiation: an effective mode of processing food for safety, p. 251-279. In Food irradiation processing. International Atomic Energy Agency Publication 695. International Atomic Energy Agency, Vienna, Austria.
  1. Mossel, D. A. A., and D. M. Drake. 1990. Processing food for safety: avenues to consumer information and reassurance. Food Technol. 44(12):63-67.
  1. Mossel, D. A. A., and C. B. Struijk. 1992. The contribution of microbial ecology to management and monitoring of the safety, quality and acceptability (SQA) of foods, p. 1S-22S. In R. G. Board, D. Jones, R. G. Kroll, and G. L. Pettipher (ed.), Ecosystems: microbes: food. Blackwell, Oxford, United Kingdom.
  1. Mossel, D. A. A., and C. B. Struijk. 1993. Food-borne illness 1993: updating Wilson's triad. Lancet 342:1254.[Medline]
  1. Mossel, D. A. A., and C. B. Struijk. 2000. A global perspective on management through education of microbiological food safety issues, p. 144-166. In Proceedings of the Symposium Exploring People, Food, and Agriculture. University of Minnesota, Minneapolis, Minn.
  1. Proctor, M. E., M. Hamacher, M. L. Tortorello, et al. 2001. Multistate outbreak of Salmonella serovar Muenchen infections associated with alfalfa sprouts grown from seeds treated with calcium hypochlorite. J. Clin. Microbiol. 39:3461-3465.[Abstract/Free Full Text]
  1. Rajkowski, K. T., and D. W. Thayer. 2000. Elimination of Salmonella spp. and strains of Escherichia coli O157:H7 by gamma irradiation of inoculated sprouts. J. Food Prot. 63:871-875.[Medline]


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