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Journal of Clinical Microbiology, August 2002, p. 3109, Vol. 40, No. 8
0095-1137/02/$04.00+0 DOI: 10.1128/JCM.40.8.3109.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Eventual Management of Sprout-Transmitted Salmonellosis

LETTER
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 10
4, until recently considered
to 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
Enterobacteriaceae is not surprising. A sporadic cell, stemming from the enterically
contaminated 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).

FOOTNOTES
Ed. Note: The authors of the published article did not respond. 

REFERENCES
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]
2 - 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]
3 - Fan, X., and D. W. Thayer. 2001. Quality of irradiated alfalfa sprouts. J. Food Prot. 64:1574-1578.[Medline]
4 - 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]
5 - 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.
6 - 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.
7 - 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.
8 - Mossel, D. A. A., and C. B. Struijk. 1993. Food-borne illness 1993: updating Wilson's triad. Lancet 342:1254.[CrossRef][Medline]
9 - 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.
10 - 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]
11 - 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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Corry B. Struijk* D. A. A. Mossel*
Eijkman Foundation, Utrecht University, P.O. Box 6024, 3503 PA Utrecht, The Netherlands
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* Phone: 31 30 2933019 Fax: 31 30 2948687 |
Journal of Clinical Microbiology, August 2002, p. 3109, Vol. 40, No. 8
0095-1137/02/$04.00+0 DOI: 10.1128/JCM.40.8.3109.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.