Infectious Diseases News Brief - December 11, 2009

[Current Issue -Table of contents]

Salmonella Or Other Bacteria Found In Most Chickens Sold In Stores, US

According to a survey by a consumer organization, most chickens sold in US stores carry salmonella and/or campylobacter, the leading bacterial causes of foodborne disease. The survey report will appear in the January 2010 issue of Consumer Reports Magazine, and describes how an analysis of fresh, whole broilers bought at stores throughout the US showed that two-thirds contained salmonella and/or campylobacter. Consumer Reports bought 382 chickens from over 100 supermarkets, mass merchandisers, gourmet and natural food stores in 22 states, and had them analyzed by outside labs. The tests revealed that: 62 per cent of the chickens contained campylobacter; 14 per cent of them contained salmonella, however, 9 per cent of the chickens contained both campylobacter and salmonella; and, only 34 per cent of the birds were clear of both pathogens. This is double the percentage of clean birds found in the 2007 survey but considerably less than the 51 per cent found in 2003. Some of the cleanest overall were the air-chilled broilers; and, about 40 per cent of which had one or both pathogens. Estimates from the US Centers for Disease Control and Prevention (CDC) suggest that every year, 3.4 million Americans are infected, 25,500 end up in hospital, and about 500 die as a result of ingesting salmonella and campylobacter from chicken and other foods. And of those people who seek medical help, about 1 in 5 infected with salmonella and over half infected with campylobacter, have antibiotic resistant strains and have to try two or more antibiotics before they find one that works.

Source: Medical News Today December 2, 2009

http://www.medicalnewstoday.com/articles/172784.php

Scientists Gain New Understanding Of Disease-Causing Bacteria

A team of scientists from The Forsyth Institute, the University of Connecticut Health Center, the CDC and the Wadsworth Center, have used state-of-the-art technology to elucidate the molecular architecture of Treponema pallidum, the bacterium which causes syphilis. The previously unknown detailed structure of the bacteria can now be shown in three dimensions. This provides the first real image of the pathogen and reveals previously unknown features, which may help fight the spread of syphilis. Cryo-electron tomography (CET) is a type of microscope that is used to obtain a three-dimensional reconstruction of a sample from two dimensional images at extremely low temperatures. Using CET, the research team has clarified the fundamental differences between Treponema pallidum and other gram-negative bacteria. After a sharp decrease in the rate of primary and secondary syphilis cases in the 90s, since the year 2000 the CDC has observed a steady increase in prevalence. The over 36,000 cases recorded annually affect both men and women as well as newborns with congenital syphilis. Over a decade ago, the publication of the Treponema pallidum genome sequence provided a much needed parts list for the bacterium. However, scientists have learned very little about how these components are organized to create this extremely virulent and immuno-evasive pathogen. CET has emerged as a powerful tool for bridging the knowledge gap. With this technique, thin films of cells are frozen to preserve cell structure in a close-to-native state, avoiding degradation caused by preparation for traditional microscopy. A series of images acquired as the sample is progressively tilted in an electron microscope are used to generate a 3D image. With CET T. pallidum cells appeared to form flat waves and did not contain an outer coat. This highly motile organism can attach to human cells by its tip. The present work has shown that the tip of this bacteria has a unique structure among pathogens, which improved the understanding of cell attachment and tissue penetration. Additionally, novel structural evidence explains how those bacteria mysteriously move with the flagella inside their cell body.

Source: Medical News Today December 1, 2009
http://www.medicalnewstoday.com/articles/172592.php

First Genetic Resistance Factor Against Tuberculosis Infection Identified

Why do some people who are exposed to tuberculosis not become infected or develop the disease? Dr. Erwin Schurr and his team at the Research Institute from the McGill University Health Centre (RI-MUHC), in collaboration with Dr. Alexandre Alcais, from the Institut national de la santé et de la recherche médicale (INSERM) in Paris, has shed light on this question for the first time. Their results show that one or multiple genes might provide certain people with resistance to tuberculosis infection. Tuberculosis (TB) is an infectious disease caused by a bacterium called Mycobacterium tuberculosis (MTB). Two thirds of the world population are infected by this mycobacterium. Nevertheless, 20 per cent of people exposed to the mycobacterium are resistant to infection and can therefore, not develop the disease. " For our study, we were interested in this minority of people who live in high-exposure areas without becoming infected," said Dr. Schurr. "We tried to understand how these people develop resistance to TB infection." Their findings show the existence of a chromosomal site, or a locus, that controls resistance to TB infection. Out of the 128 families studied, who come from an area in South Africa with high tuberculosis rates, after considering non genetic factors such as age, 20 per cent of individuals show natural resistance. "In other words, some people seem to have a particular genetic heritage that makes them naturally resistant to MTB infection," explained Dr. Alcais. This is a major development for people with HIV, for whom tuberculosis is a leading cause of mortality, as it is responsible for about 13% of AIDS-related deaths in the world. "Right now, our challenge as researchers is to concentrate on identifying this genetic factor and its mechanisms that lead to resistance against TB infection," explained Dr. Alcais. The hope is that these genetic resistance factors can be used in the near future to prevent TB infection in the general population by stimulating the mechanism responsible for resistance.

Source: Science Daily December 3, 2009

http://www.sciencedaily.com/releases/2009/12/091201100556.htm