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Archives Of Infectious Disease Blog From Medicineworld.Org

December 20, 2005

Step Aside for Strep Throat Treatment

Step Aside for Strep Throat Treatment
Doctors have presented more evidence that it's time for long-time antibiotic stalwarts like penicillin and amoxicillin to step aside when it comes to the therapy of strep throat.

The most common medications used to treat the strep germ, the bug that causes millions of sore throats in U.S. children every year, simply aren't doing the job and aren't as effective as newer antibiotics known as cephalosporins. In results presented this weekend at a large infectious disease meeting, the annual Interscience Conference on Antimicrobial Agents and Chemotherapy in Washington, doctors who reviewed the therapy given to 11,426 children showed that even a short course of the newer drugs is more effective than the traditional 10-day dose of the older antibiotics.

Pediatricians at the University of Rochester Medical Center found that 25 percent of children treated for strep throat with penicillin ended up back in the doctor's office within three weeks of therapy. Children treated with amoxicillin returned 18 percent of the time. The numbers were 14 percent for older-generation cephalosporins, and just 7 percent for newer ones like cefpodoxime and cefdinir, which are given for just four or five days.

The new results buttress prior work by physicians Michael Pichichero, M.D., and Janet Casey, M.D., showing that more children who receive the older drugs relapse, prolonging their illness and forcing doctors to turn to even stronger drugs. Yet, said Pichichero, doctors across the land continue to prescribe ineffective medications. Studies have shown that approximately 60 to 80 percent of children treated for strep are prescribed amoxicillin; 10 to 20 percent are prescribed penicillin; and just 10 to 20 percent receive a cephalosporin.

"Most doctors are shocked to learn of the high failure rates of the older medications," said Pichichero, a professor of Microbiology and Immunology.........

Mark      Permalink

December 19, 2005

Weak Chlorine Solutions Can Kill Noroviruses

Weak Chlorine Solutions Can Kill Noroviruses
Chlorine solutions much weaker than previously believed can still be used to kill more than 99 percent of noroviruses, the chief cause of outbreaks of gastrointestinal illness around the world, a new University of North Carolina at Chapel Hill study concludes.

Scientists presented their findings over the weekend at the 2005 International Conference on Antimicrobial Agents and Chemotherapy, which ends today (Dec. 19) in Washington, D.C. They discovered for the first time that dilute solutions of hypochlorous acid, or free chlorine, as low as 200 -- or even 20 -- milligrams per liter will completely inactivate noroviruses on surfaces such as stainless steel and ceramic tile.

Dr. Mark D. Sobsey, professor of environmental sciences and engineering at the UNC School of Public Health, and postdoctoral fellow Dr. Geunwoo Park conducted the research. They also found that the dilute chemical worked quickly -- in five minutes or less.

"This is good news since noroviruses are the leading cause of viral gastroenteritis," said Sobsey, director of the school's Environmental Health Microbiology Laboratories. "They have caused countless outbreaks of gastroenteritis in health-care facilities, schools, food establishments, hotels and resorts and on cruise ships".

Decontamination of affected facilities can prove difficult since the viruses persist on environmental surfaces and are resistant to some widely used sanitizers, he said. And they are highly infectious even at low doses.

In their studies, the researchers dried a group II norovirus -- the predominant form circulating in the USA -- and a widely used indicator virus, bacteriophage MS2 infecting E. coli, on stainless steel and ceramic surfaces, Sobsey said. After treating those surfaces with a 200 milligrams per liter solution of hypochlorous acid for one minute, they tested them to learn how much virus remained. The viruses dropped 99.99 percent.........

Mark      Permalink

December 19, 2005

The Best Way To Cope With The Flu

The Best Way To Cope With The Flu
Tissues. Wastebaskets. Hand sanitizers.

These are some of the best weapons you may have in your arsenal to help you avoid getting - and giving - the flu this year.

Daniel Havlichek, a Michigan State University doctor and chief of the College of Human Medicine's Infectious Disease Section, said coughing or sneezing into a tissue, rather than your hand, is one of the best ways to avoid spreading germs.

"Coughing into your hand and then shaking someone else's hand or touching them or a doorknob is a great way to spread influenza or the viruses that cause the common cold," said Havlichek, an associate professor in the Department of Medicine. "A tissue will do a much better job of keeping germs from spreading. Then you just throw it away and then wash your hands. It is also important to rest and take time off if you become ill so that you don't spread infection to others".

Hand washing remains one of the most effective, and easiest, ways to avoid illness.

"Winter in particular is a time when hand washing can be effective in preventing the spread of illness," said Vincent Young, an MSU doctor who specializes in infectious diseases.

Havlichek is also a strong proponent of the use of hand sanitizers, those waterless cleaners that are popping up everywhere.

"These are as effective as washing your hands," he said. "In some respects they are even more effective at killing bacteria and viruses than soap and water, eventhough you still need to wash your hands with soap and water regularly to prevent build up of the sanitizer, which can make it less effective".

Paula Guss, a nurse with the MSU Office of the University Physician, said other ways to help avoid the flu, and other infectious illnesses, include eating right, drinking plenty of water and getting enough sleep.........

Mark      Permalink

December 17, 2005

How Chlamydia Escapes Defenses

How Chlamydia Escapes Defenses
Duke University Medical Center microbiologists have discovered that the parasitic bacteria Chlamydia escapes cellular detection and destruction by cloaking itself in droplets of fat within the cell. The scientists said that their findings represent the first example of a bacterial pathogen "mimicking" such a structure, or organelle, within a cell.

Not only do the findings suggest a novel mechanism of bacterial infection, but the new insights into Chlamydia's actions within infected cells provide rational targets for potential drugs to halt the spread of the bacteria, said the researchers. Chlamydia has been implicated in sexually transmitted infections, atherosclerosis and some forms of pneumonia.

Chlamydia is an obligate intracellular parasite that prospers within a host cell by hijacking the cell's internal machinery to survive and replicate. The bacterium lives within the cell in a protective capsule known as an inclusion. To date, it has not been clearly understood how Chlamydia has evolved to evade the cell's internal intruder alert system.

"In our experiments, we found that Chlamydia recruits lipid droplets from within the cell and stimulates the production of new droplets, which cover the surface of the inclusion," explained Yadunanda Kumar, Ph.D., a post-doctoral fellow in Duke's Department of Molecular Genetics and Microbiology. "This action of surrounding itself with lipid droplets may represent an example of organelle mimicry, where the chlamydial inclusion is protected from the cell's defenses by being perceived by the cell as just another lipid droplet."

Kumar presented the results of the Duke research Dec. 11, 2005, at the 45th annual meeting of the American Society for Cell Biology in San Francisco. The research was supported by National Institutes of Health, the Pew Foundation and the Whitehead Foundation.........

Mark      Permalink

December 16, 2005

Microbial Choreography

Microbial Choreography
Birds fly together in flocks. Fish swim together in schools. Everyone has seen the beautiful, seemingly choreographed motions these collections of organisms can exhibit.

But surely bacteria, which have no eyes or brain, cannot behave in such a coordinated way. In fact, they do, and scientists are beginning to learn how.

Bacteria are well known to interact with one another through chemical signals - they can "smell" one another, and their behavior and growth may change if they have a number of neighbors. Chemical signaling between bacteria enables cooperative behavior of a bacterial population; one example of this is "cell swarming," where colonies of bacteria grown in a petri dish form complex and beautiful patterns.

More recently, experiments in several laboratories have shown that bacteria swimming in a drop of water also form patterns-jets and whirls that are much larger than the bacteria themselves, and that stir the fluid in ways that an individual swimming bacterium cannot. A key question then is: How do the swimming bacteria interact to form these patterns? .

Reporting in the November 11 issue of Physical Review Letters, Chemical and Biological Engineering Professor Mike Graham's group at the University of Wisconsin-Madison developed a model that offers a partial answer to this question. In this model, each bacterium pushes fluid around as it swims, and simultaneously is buffeted like a boat on a wavy sea by the fluid motions generated by all the other swimming bacteria.

View the depiction of the model online.

There are no other interactions between the bacteria in this model: They cannot smell, feel or see one another, says Graham. This model might be expected to just predict random, uncoordinated swimming of the bacteria, and indeed at low concentrations this is exactly what occurs.........

Mark      Permalink

December 15, 2005

E. Coli Bacterium Generates Simplicity From Complexity

E. Coli Bacterium Generates Simplicity From Complexity
The ubiquitous and commonly harmless E. coli bacterium, which has one-seventh the number of genes as a human, has more than 1,000 of them involved in metabolism and metabolic regulation. Activation of random combinations of these genes would theoretically be capable of generating a huge variety of internal states; however, scientists at UCSD will report in the Dec. 27 issue of Proceedings of the National Academy of Sciences (PNAS) that Escherichia coli doesn't gamble with its metabolism. In a surprise about E. coli that may offer clues about how human cells operate, the PNAS paper reports that only a handful of dominant metabolic states are found in E. coli when it is "grown" in 15,580 different environments in computer simulations.

"When it comes to genomes, a great deal of complexity boils down to just a few simple themes," said Bernhard Palsson, a professor of bioengineering at UCSD's Jacobs School of Engineering and co-author of the study, which was made available online Dec. 15. "Scientists have confirmed the complexity of individual parts of biochemical networks in E. coli and other model organisms, but our large-scale reconstruction of regulatory and metabolic networks involving hundreds of these parts has shown that all this genetic complexity yields surprisingly few physiological functions. This is possibly a general principal in a number of, if not all, species."

Palsson and colleagues at UCSD, postdoctoral fellows Christian L. Barrett and Christopher D. Herring, and Ph.D. candidate Jennifer L. Reed, created a computer model of an E. coli cell based on the experimental results of thousands of prior experiments, some of which were completed decades ago. "The goal of this study was to comprehensively simulate all the possible molecular interactions in a well studied strain of E. coli to gain a global view of the range of functional network states," said Barrett. "Complex cellular networks can potentially generate lots of different behaviors, but we find that cells utilize only a few of them."........

Mark      Permalink

December 14, 2005, 7:24 PM CT

Mathematics For Discerning Immune Response

Mathematics For Discerning Immune Response
The National Institutes of Health (NIH) has awarded the University of Pittsburgh School of Medicine a five-year, $9.1 million contract to develop sophisticated mathematical models for investigating how the immune system responds to the pathogens that cause flu, tuberculosis (TB) and tularemia, an particularly dangerous infection that some authorities believe could be used as a biological weapon. Such models should help expedite the development of vaccines and therapies against these and other infectious agents and help scientists and public health officials in their efforts to predict or prevent disease outbreaks as well as determine the best courses of therapy.

The contract establishes Pitt as an Immune Modeling Center, one of four supported by the NIH's National Institute of Allergy and Infectious Diseases (NIAID), and takes advantage of Pitt's existing collaborations with Carnegie Mellon University and the University of Michigan.

"This center's work will draw upon our expertise in mathematical modeling of the immune system as well as our knowledge about immunity to infectious diseases. Working as a team of immunologists, computational biologists, computer researchers and mathematicians, our goal is to capture the complexity of the immune system through mathematics," said Penelope A. Morel, M.D., associate professor of immunology and medicine at the University of Pittsburgh School of Medicine and principal investigator of the Pitt-based Immune Modeling Center. Shlomo Ta'asan, Ph.D., professor of mathematics in Carnegie Mellon's Mellon College of Science, is co-principal investigator of the center.

The Immune Modeling Center will focus on understanding the innate, or natural, and adaptive immune responses to influenza A virus, Mycobacterium tuberculosis, which causes TB, and Francisella tularensis, the bacterium responsible for tularemia. Since each of these organisms enters the body via the lung, the investigators will study the specific immune cells recruited to the lung and identify the particular genes expressed and the molecules produced in response to infection. A combination of mathematical and animal models will be employed to test different vaccine and therapeutic strategies, including a novel approach that aims to enhance immune response through certain proteins called cytokines.........

Mark      Permalink

December 14, 2005

Getting That Tattoo From Your Skin

Getting That Tattoo From Your Skin
If you didn't believe your mom when she said that you would regret getting your beloved's name tattooed on your arm - you are not alone.

Tattoos are an ancient tradition. In some cultures, tattooing was done for prestige and was very sacred. Today, people get tattoos in memory of loved ones, as a sign of rebellion or just to be cool.

However, tattoos can carry many health risks.

"If not done properly, the most common health risks are scarring, allergic reactions, and Hepatitis C," said Dr. Ramsey Markus, an assistant professor of dermatology and director of the dermatology laser center at Baylor College of Medicine in Houston. "Allergic reactions are especially bothersome as they are often chronic, itchy and difficult to treat. Red inks are the most likely to cause allergic reactions.".

There's no cure for Hepatitis C, which is a liver disease caused by the Hepatitis C virus. Infections can occur in new tattoos, particularly without appropriate after care.

A tattoo is a puncture wound, made deep in your skin, that's filled with ink. Tattoos are long-lasting because they are injected into the dermis, the second layer of skin where the cells are stable and do not shed.

Unfortunately, it's often more expensive to remove a tattoo than it is to get one. Dermatologists at Baylor College of Medicine are using the Medlite C6 laser, one of the safest and fastest tattoo removal lasers.

"Before the latest laser technology, the only way to remove a tattoo was surgically," Markus said. "The tattoo would be cut out, burned off or sanded away. Salabrasion, or sanding the skin and rubbing in salt, was also effective.".

The Medlite C6 laser produces a beam of laser light that passes through the skin to break up the ink. The ink particles that are small enough are removed gradually for up to three months by the immune system. The therapy takes a few minutes depending on the size and color of the tattoo.........

Sue      Permalink

December 14, 2005

The Disease That Ravaged Napoleon's Army

The Disease That Ravaged Napoleon's Army
Using dental pulp extracted from the teeth of soldiers who died during Napoleon's disastrous retreat through Russia in 1812, a new study finds DNA evidence that epidemic typhus and trench fever ran rampant among the French Grand Army. The study, published in the Jan. 1 issue of The Journal of Infectious Diseases, now available online, identifies the specific species of louse-borne pathogens that were a major cause of death among the remains of the retreating army.

Napoleon marched into Russia in the summer of 1812 with a half-million soldiers. Only a few thousand staggered out again, victims of war, weather, and disease. Twenty-five thousand arrived in Vilnius that winter, but only 3,000 lived to continue the retreat. The dead were buried in mass graves.

Construction work in 2001 unearthed one such grave, containing between 2,000 and 3,000 corpses. Didier Raoult, MD, PhD, from the Universite de la Mediterranee in Marseille, France, and his colleagues identified body segments of five lice in a forensic excavation of two kilograms of earth containing fragments of bone and remnants of clothing. Three of the lice carried DNA from Bartonella quintana, which causes the disease usually known as trench fever, which afflicted a number of soldiers in World War I.

The team analyzed dental pulp from 72 teeth, taken from the remains of 35 soldiers. Dental pulp from seven soldiers contained DNA from B. quintana, and pulp from three soldiers contained DNA from Rickettsia prowazakii, which causes epidemic typhus. Testing for other organisms gave negative results, and other appropriate controls were negative.

In all, 29 percent of the soldiers tested had evidence of either R. prowazkii or B. quintana infection, suggesting that louse-born diseases such as typhus and trench fever may have been a major factor contributing to Napoleon's retreat from Russia. The authors conclude that searching for DNA of infectious agents in dental pulp may become an important tool for investigating the history of communicable diseases.

Mark      Permalink

Send Teens the Message about the Link Between Drug Abuse and HIV (December 11, 2005)
Drug Abuse and HIV: Learn the Link" is the message of a new public awareness campaign announced November 29, 2005, by the National Institute on Drug Abuse (NIDA), a component of the National Institutes of Health. "Drug abuse prevention is HIV prevention," says NIDA Director Dr. Nora D. Volkow. "Research has shown that a significant proportion of young people are not concerned about becoming infected with HIV. In recent years, the number of young people in the United States diagnosed with AIDS rose substantially. Because drug use encourages risky behaviors that can promote HIV transmission, NIDA views drug abuse therapy as essential HIV prevention."

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Did you know?
Scientists at Baylor College of Medicine in Houston have found a genetic marker that may identify individuals at greater risk for life-threatening infection from the West Nile virus. Results of the study are reported in the Nov. 15 print edition of Journal of Infectious Diseases. Archives of infectious disease blog

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