Featured Research

from universities, journals, and other organizations

Sharpening a test for tracing food-borne illness to source

Date:
June 23, 2014
Source:
American Society for Microbiology
Summary:
Research could make it easier for public health investigators to determine if a case of food poisoning is an isolated incident or part of a larger outbreak. The study focuses on a test called multi-locus variable number tandem repeats variable analysis (MLVA). The test, which is increasingly used in the detection and investigation of foodborne outbreaks, analyzes specific sequences of DNA (called loci) that change rapidly enough over time to distinguish outbreak strains from other circulating strains of the bacteria but not so rapidly that connections could be masked by changes arising during the course of an outbreak.

Research from the University of Melbourne, Australia, could make it easier for public health investigators to determine if a case of food poisoning is an isolated incident or part of a larger outbreak. The findings are published ahead of print in the Journal of Bacteriology.

The study focuses on a test called multi-locus variable number tandem repeats variable analysis (MLVA). The test, which is increasingly used in the detection and investigation of foodborne outbreaks, analyzes specific sequences of DNA (called loci) that change rapidly enough over time to distinguish outbreak strains from other circulating strains of the bacteria but not so rapidly that connections could be masked by changes arising during the course of an outbreak.

However, the rates at which MLVA profiles change have not been directly investigated for Salmonella, and thus it is sometimes unclear how these profiles should be interpreted in the context of outbreak detection and investigation.

In the study, the investigators grew an isolate of Salmonella Typhimurium from an Australian food poisoning outbreak, and observed changes in its MLVA profile during more than 28,000 generations of growth in the laboratory. Then, using the same bacterial lineage, they observed changes in MLVA profile during 500 days of growth in mice.

They estimated the rates of copy number change at each of the five loci that are commonly used for S. Typhimurium MLVA. Three of the loci saw changes in the DNA, but two did not. Based on these results, the researchers are recommending that isolates with zero or one variation in the three rapidly changing loci but no differences in the other two should be considered part of the same cluster.

They also noted that the relative rates of change among the loci were the same in the Petri dish studies and in the mouse study.

"This tells us we don't need to worry about where the bacteria were isolated from -- humans or food," says Kathryn Holt, an author on the study.

MLVA is used for investigations of food-borne illnesses besides Salmonella, including Listeria, and E. coli. It is the primary method for investigations of Salmonella outbreaks in Europe, the UK, Australia, and elsewhere, says Holt.

"In the U.S., the Centers for Disease Control and Prevention uses another technique called PFGE for initial investigations and follows that with MLVA," she says.


Story Source:

The above story is based on materials provided by American Society for Microbiology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Kathryn Holt et al. Analysis of Salmonella Typhimurium variable number tandem repeat (VNTR) data for public health investigation based on measured mutation rates and whole-genome sequence comparisons. Journal of Bacteriology, June 2014 DOI: 10.1128/JB.01820-14

Cite This Page:

American Society for Microbiology. "Sharpening a test for tracing food-borne illness to source." ScienceDaily. ScienceDaily, 23 June 2014. <www.sciencedaily.com/releases/2014/06/140623131159.htm>.
American Society for Microbiology. (2014, June 23). Sharpening a test for tracing food-borne illness to source. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2014/06/140623131159.htm
American Society for Microbiology. "Sharpening a test for tracing food-borne illness to source." ScienceDaily. www.sciencedaily.com/releases/2014/06/140623131159.htm (accessed October 20, 2014).

Share This



More Health & Medicine News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How Nigeria Beat Its Ebola Outbreak

How Nigeria Beat Its Ebola Outbreak

Newsy (Oct. 20, 2014) The World Health Organization has declared Nigeria free of Ebola. Health experts credit a bit of luck and the government's initial response. Video provided by Newsy
Powered by NewsLook.com
Another Study Suggests Viagra Is Good For The Heart

Another Study Suggests Viagra Is Good For The Heart

Newsy (Oct. 20, 2014) An ingredient in erectile-dysfunction medications such as Viagra could improve heart function. Perhaps not surprising, given Viagra's history. Video provided by Newsy
Powered by NewsLook.com
Ebola Worries End for Dozens on U.S. Watch Lists

Ebola Worries End for Dozens on U.S. Watch Lists

Reuters - US Online Video (Oct. 20, 2014) Forty-three people who had contact with Thomas Eric Duncan, the first person diagnosed with Ebola in the U.S., were cleared overnight of twice-daily monitoring after 21 days of showing no symptoms. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
CDC Calls for New Ebola Safety Guidelines

CDC Calls for New Ebola Safety Guidelines

AP (Oct. 20, 2014) Centers for Disease Control and Prevention Director Dr. Tom Frieden laid out new guidelines for health care workers when dealing with the deadly Ebola virus including new precautions when taking off personal protective equipment. (Oct. 20) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins