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Methods and Compositions for Selectively Enriching Microbes

The described technology provides markedly improved enrichment of E. coli O157:H7, Shiga toxin-producing E. coli (STEC) and Shigella. This improved enrichment can be complimentary to, and enhance performance of, existing nucleic acid or antibody based detection methods. In addition, the improved enrichment method facilitates isolation of pathogens following positive results by any nucleic acid or antibody based test. Such isolation by cultural methods is essential for epidemiology, antibiotic sensitivity testing and other biochemical characterization.

Current enrichment protocols are often inadequate as they allow large numbers of interfering bacteria to grow. This makes it necessary for microbiologists to screen hundreds of presumptive colonies to achieve successful isolation (A Khan et al., Emerg Infect Dis. 2002 Jan; 8:54-62). The new technology is a simple two step process. The sample is first placed in a low pH solution for a brief period and then transferred to a medium permitting maximal growth of target bacteria. With this new technology there is no risk of false negative results due to inadvertent inhibition of target bacteria by novobiocin, tellurite, cefixime, or other additives commonly used in existing enrichment procedures.

This new technology has been shown to be effective with food, water, environmental and clinical samples. Its components are inexpensive and microbiologists are not required to impede their workflow by adding separate selective agents at specified intervals such as four or six hours.

Potential Commercial Applications:

Improved detection of E. coli O157:H7, STEC and Shigella in:

  • Clinical samples
  • Food
  • Beverages
  • Dairy
  • Water
  • Wastewater
  • Environmental
  • Veterinary Samples

Competitive Advantages:

  • Simple
  • Inexpensive
  • Requires no addition of antibiotic or other inhibitor solutions
  • Reduces interfering bacterial competitors and makes detection of target pathogens easier

Michael Grant

Intellectual Property:
US Application No. 11/155,879
US Application No. 10/539,765
PCT Application No. PCT/US2003/40806

MA Grant. Comparison of Escherichia coli O157:H7 enrichment in spiked produce samples. J Food Prot. 2008 Jan;71(1):139-145. PubMed abs
MA Grant. Comparison of a new enrichment procedure for Shiga toxin-producing Escherichia coli with five standard methods. J Food Prot. 2005 Aug;68(8):1593-1599. PubMed abs
MA Grant. Improved laboratory enrichment for enterohemorrhagic Escherichia coli by exposure to extremely acidic conditions. Appl Environ Microbiol. 2004 Feb;70(2):1226-1230.
Submitted for publication – two papers demonstrating effectiveness of new enrichment procedure with clinical and environmental samples.

Collaboration Opportunity:
The FDA is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize methods for detecting pathogenic bacteria, especially E. coli O157:H7, Shiga toxin-producing E. coli (STEC) and Shigella. Please contact Alice Welch at Alice.Welch@fda.hhs.gov for more information.

Licensing Contact:
Bill Ronnenberg, JD-MIP, MS
FDA Technology Transfer Program
10903 New Hampshire Ave.
Building WO1, Rm 4214
Silver Spring, MD 20993
Email: FDAInventionlicensing@fda.hhs.gov
Phone: 240-402-4561

OTT Reference No: E-228-2002/0
Updated: August 9, 2015

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