BBSRC-funded researchers at Cambridge University have shed new light on a common food poisoning bug. Using real-time video microscopy, coupled with mathematical modelling, they have changed our assumptions about Salmonella and how it infects human cells. The research was published in Interface. "Live reinfection by Salmonella " Salmonella is an important bacterium to study as it causes a range of diseases in humans and animals. It is capable of growing and reproducing inside macrophages - a type of white blood cell that ingests foreign material - ultimately destroying them. These macrophage cells are key players in the immune response to invaders and so the control of Salmonella within these cells is critical to surviving an infection. However, fundamentally important factors in infection events - such as the rate at which Salmonella infects cells, how frequently this occurs and the probability of infection - had not previously been calculated because it was thought impossible to do so.
With summer days at the beach on the minds of millions of winter-weary people, a new study provides health departments with information needed to determine when levels of disease-causing bacteria in beach sand could pose a risk to children and others who dig or play in the sand. The report appears in ACS' journal Environmental Science & Technology. Tomoyuki Shibata and Helena M. Solo-Gabriele explain that disease-causing bacteria from sewage can cause skin infections and gastrointestinal (GI) disorders in people who come into contact with contaminated water. The U.S. Environmental Protection Agency (EPA) has guidelines to determine when microbe levels in water are high enough to pose an unacceptable risk of GI illness for contact with both ocean water and freshwater. Microbes, however, tend to concentrate in higher levels in beach sand - to the point where one previous study found that the sand on one fingertip, placed in the mouth, had enough germs to cause GI illness.
A recent discovery of "hypervirulent" Salmonella bacteria has given UC Santa Barbara researchers Michael Mahan and Douglas Heithoff a means to potentially prevent food poisoning outbreaks from these particularly powerful strains. Their findings, in a paper titled "Intraspecies Variation in the Emergence of Hyperinfectious Bacterial Strains in Nature, " have been published in the journal PLoS Pathogens. Salmonella is the most common cause of infection, hospitalization, and death due to foodborne illness in the U.S. This burden may continue to worsen due to the emergence of new strains that would tax current health-control efforts. To address this problem, researchers sought out - and found - hypervirulent strains that present a potential risk to food safety and the livestock industry. An international team of scientists - which also included Robert Sinsheimer and William Shimp from UCSB;
The specific mechanisms by which humans and other animals are able to discriminate between disease-causing microbes and innocuous ones in order to rapidly respond to infections have long been a mystery to scientists. But a study conducted on roundworms by biologists at UC San Diego has uncovered some important clues to finally answering that question. In a paper published in the early online issue of the journal Cell Host & Microbe, the researchers discovered that intestinal cells in the roundworm C. elegans, which are similar in structure to those in humans, internalize bacterial toxins that inactivate several host processes. This then triggers an immune response, which results in the body mounting an immediate attack against the disease-causing microbes. "The human intestine is teeming with trillions of bacteria, most of which are innocuous, or even beneficial, " said Emily Troemel, an assistant professor of biology at UC San Diego who headed the study.
Early colonization of the gut by microbes in infants is critical for development of their intestinal tract and in immune development. A new study, published in BioMed Central's open access journal Genome Biology, shows that differences in bacterial colonization of formula-fed and breast-fed babies leads to changes in the infant's expression of genes involved in the immune system, and in defense against pathogens. The health of individuals can be influenced by the diversity of microbes colonizing the gut, and microbial colonization can be especially important in regulating both intestinal and immune development in infants. However, little is known about the potential interactions between the host's health at a molecular level, their gut microbes, and diet. The human intestine is lined by epithelial cells that process nutrients and provide the first line of defense against food antigens and pathogens.