Growth of Escherichia Coli O157:H7 During Sprouting of Alfalfa Seeds

Lett Appl Microbiol. 2001 Aug;33(2):95-9. doi: 10.1046/j.1472-765x.2001.00957.x.


Aims: Escherichia coli O157:H7 was monitored daily during sprouting of alfalfa seeds inoculated at high (3.92 log10 cfu g(-1)) and low (1.86 log10 cfu g(-1)) levels to assess the extent of pathogen growth during production.

Methods and results: Sprouts and rinse water were tested by direct and membrane filter plating on modified sorbitol MacConkey agar and BCM O157:H7(+) agar; the antibody-direct epifluorescent filter technique; and rapid immunoassays. The pathogen reached maximum populations after one and two days of sprouting seeds inoculated at high and low levels, respectively; in either case, populations of 5-6 log10 cfu g(-1) were reached. Detection limits of two rapid immunoassays, Reveal and VIP, without enrichment were determined to be 5-7 log10 cfu ml(-1).

Conclusion: These results show the ability of E. coli O157:H7 to grow to high levels during sprouting; however, because these levels may be below detection limits, it is necessary to include enrichment when monitoring sprout production for E. coli O157:H7 by the rapid test kits.

Significance and impact of the study: The data indicate that sprouts may harbor high levels of pathogens. The appropriate use of rapid test methods for pathogen monitoring during sprouting is indicated.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Colony Count, Microbial
  • Escherichia coli O157 / growth & development
  • Escherichia coli O157 / isolation & purification*
  • Food Contamination*
  • Food Handling / methods
  • Food Microbiology
  • Immunomagnetic Separation
  • Medicago sativa / microbiology*
  • Seeds / microbiology
  • Temperature
  • Water Microbiology