Bacteriophages may function as novel antimicrobials.

It appears that some foodborne bacteria may be overstaying their welcome in products after bacteriophages take up residence inside them and replicate. The progeny of these bacteriophages literally kill their bacterial hosts on their way out the cellular door.

Bacteriophages are environmentally ubiquitous and only attack bacteria. Interest in bacteriophages is ramping up with the emergence of antibiotic-resistant organisms. USDA-ARS researchers and scientists at Intralytix Inc., Baltimore, MD, are jointly working on bacteriophages. The investigators at Intralytix isolate environmental phage viruses and select candidates for further study. The ARS technologists test their ability to infect and kill bacteria.

The purified viruses that ARS scientists are testing can wreak havoc on deadly bacteria such as E. coli O157:H7. Phages reproduce by insinuating themselves into bacteria. Viral DNA is injected into the cells of the bacterial hosts, where it directs the production of progeny phages. These phages burst from bacterial-host cells, killing their hosts along the way, and then move on to infect more bacterial cells.

ARS researchers have tested a cocktail of phages on refrigerated samples of fresh-cut cantaloupe. These trials indicated that the phage treatments could be effective in killing E. coli O157:H7 in a produce commodity. The treatments reduced pathogens on the samples of fresh-cut cantaloupe by 100-fold over untreated controls.

The scientists also have tested the phages on their prime target: refrigerated fresh-cut lettuce. The results indicate that bacteriophage treatments can kill E. coli O157:H7 on the surface of leafy greens at the same levels as on the fresh-cut cantaloupe.

The next step for Intralytix is obtaining regulatory approval. This is in process. Once the approval is obtained, the company will start marketing the product to various food producers. Intralytix already has another bacteriophage-based product (LMP-102) approved by the FDA and, more recently, by the EPA. This product is targeted against L. monocytogenes. It will be available to food producers this year. As for the E. coli O157 product, it will be available shortly after FDA approves it. Assuming no major delays in the FDA approval, it should be later this year or early next year. All bacteriophages in the company's preparations are patented. It also has patents and patent applications related to uses, manufacturing and the like.

Further information. Alexander Sulakvelidze, Ph.D., Vice President, Research and Development, Chief Scientist, Intralytix, Inc., The Columbus Center, 701 E. Pratt St., Baltimore, MD 21202; phone: [phone]; fax: [phone]; email: [e-mail]; URL: www.intralytix.com. Manan Sharma, USDA-ARS Food Safety Laboratory, 10300 Baltimore Ave., Building 201, Beltsville, MD 20705; phone: [phone]; fax: [phone]; email: [e-mail].