Posted on June 15, 2011 by BioJobBlogger

TWiM #9: Bean sprouts and E. coli O104:H4

On episode #9 of the podcast This Week in Microbiology, Vincent, Cliff, and Michael review the outbreak of bloody diarrhea and hemolytic uremic syndrome in Germany caused by Shiga toxin-producing Escherichia coli O104:H4.

Hosts: Vincent Racaniello, Cliff Mintz, and Michael Schmidt.

Right click to download TWiM #9 (53 MB, .mp3, 76 minutes).

Subscribe to TWiM (free) on iTunes, Zune Marketplace, via RSS feed, by email or listen on your mobile device with the Microbeworld app.

Links for this episode:

Send your microbiology questions and comments (email or mp3 file) to twim@twiv.tv , or call them in to 908-312-0760. You can also post articles that you would like us to discuss at microbeworld.org and tag them with twim.

 


 

Tags: , , , , , , , , , , ,
Posted on June 1, 2011 by BioJobBlogger

A Massive Enterohemorrhagic Escherichia coli Outbreak is Ravaging Northern Europe

A massive foodborne outbreak of enterohemorrhagic E. coli (EHEC; typically E. coli 0157:H7) has caused16 deaths and sickened over 470 persons in Northern Europe. The source of the outbreak is thought to be fecally-contaminated raw vegetables including cucumbers, tomatoes and leaf lettuce. The source of the outbreak is still uncertain. German public health officials initially pointed to several cucumbers from Spain as the culprits. But, while these products were contaminated with EHEC, it appears that a different EHEC is responsible for the German outbreak.

Most of the sickened individuals are in Northern Germany although public health officials fear that the outbreak may spread. To that end, the outbreak appears to have worsened over the last 24 hours, with nearly 100 more people suffering from severe and potentially fatal symptoms. Typically, there are only 50 to 60 cases of EHEC infections per year in Germany.

Fecal contamination of the raw vegetables is the likely cause of this massive outbreak because E. coli is found in large quantities in the digestive systems of humans, cows and other mammals. Enteropathogenic strains of E. coli have been responsible for a large number of food contamination outbreaks in a wide range of countries. In most cases, the disease caused by these organisms is characterized by severe abdominal pains, diarrhea and generalized malaise. However, EHEC can cause more severe symptoms, ranging from bloody diarrhea to the rare hemolytic uremic syndrome which can lead to kidney failure, seizures, strokes, comas and death. The uremic syndrome is caused by secretion of a potent and sometime lethal enterotoxin manufactured by EHEC.

Unlike Salmonella gastroenteritis, where large number of organisms must be ingested to cause disease, EHEC infections can be caused by far fewer bacteria following ingestion of contaminated foodstuffs. In this regard, infections caused by EHEC are similar to those caused by Shigella spp which can be caused by between 1 to 10 ingested bacteria.

Let’s hope that the source of the outbreak is quickly identified before more people get sick or die.

Until next time...

Good Luck and Wash All Raw Vegetables Before Eating!!!!!!

 

Tags: , , , , , , , , , , , , , , , , , , ,
Posted on February 11, 2008 by BioJobBlogger

The Skinny on Artificial Sweeteners

Over the past few years, I have heard rumors that artificial sweeteners like saccharine, aspartame and sucralose actually cause people to gain rather than lose weight. I summarily dismissed these stories because they did not make sense to me nor did I think that they had any scientific merit–until today!

Purdue University psychologists Drs. Susan Swithers and Terry Davidson fed rats yoghurt sweetened with glucose (15 calories per teaspoon) or yoghurt containing the artificial sweetener saccharin (0 calories per teaspoon). Rats that were fed the saccharin-sweeten yoghurt subsequently consumed more calories, gained more weight, put on more body fat and were unable to regulate dietary intake of calories as compared with rats that were fed glucose-sweetened yoghurt. The authors surmised that breaking the connection between a sweet sensation and high-calorie food, changes the body’s ability to regulate caloric intake. This could partly explain why obesity has risen with the increasing use of artificial sweeteners in drinks. The study’s findings are consistent with emerging evidence that people who drink more diet drinks are at higher risk for obesity and development of the metabolic syndrome that increases the risk for heart disease and diabetes.

So, how do the authors explain their seemingly paradoxical findings? Swithers and Davidson postulate that ingestion of sugar-rich (sweet) foods provides a ‘salient orosensory stimulus” that signals that the body is about ingest a lot of calories. This, in turn, induces the body to physiologically-prepare itself for ingestion of a high calorie meal. However, when the false sense of sweetness (provided by the artificial sweetener) is not followed by consumption of large amounts of calories, the system gets “confused”– causing people to eat more or expend less energy to account for the calorie imbalance. Nevertheless, the good news is that people who use artificial sweeteners can still count calories to regulate caloric intake and body weight. Unfortunately, as the authors suggest, counting calories requires a more conscious effort and a lot more work than routinely consuming low-calorie foods.

Although this study was conducted in rats, its findings are consistent with the observations that increased use of artificial sweeteners can contribute to human weight gain. Despite the study’s findings, similar experiments must be conducted in people to substantiate or refute the authors’ hypothesis.

Until next time…

Good Luck and Good Job Hunting (lay off the aspartame and splenda)!!!!!!

Tags: , , , , , , , , ,