Category Archives: Antibiotics

Skin Bacteria

Close Look at Human Arm Finds Host of Microbes:

“The skin is home to a virtual zoo,” said Blaser, a microbiologist who last week published online the first molecular analysis of the bacteria living on one small patch of human skin. “We’re just beginning to explore it.” The analysis revealed that human skin is populated by a diverse assortment of bacteria, including many previously unknown species, offering the first detailed peek at this potentially crucial ecosystem.

The work is part of a broader effort by a small coterie of scientists to better understand the microbial world that populates the human body. Virtually every orifice and the digestive tract are swarming with bacteria, fungi and other microbes. By some estimates, only one out of every 10 cells in the body is human.
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Blaser’s team swabbed an area of skin about the size of silver dollar on the right and left forearms of three healthy men and three healthy women. They then used sophisticated molecular techniques to amplify and analyze fragments of bacterial DNA captured by the swabs. The analysis revealed 182 species, the researchers reported. Of those, 30 had never been seen. They identified an additional 65 species when they sampled four of the volunteers eight to 10 months later, including 14 new species.

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Antibiotic resistance: How do antibiotics kill bacteria?

Many, if not most, antibiotics act by inhibiting the events necessary for bacterial growth. Some inhibit DNA replication, some, transcription, some antibiotics prevent bacteria from making proteins, some prevent the synthesis of cell walls, and so on. In general, antibiotics keep bacteria from building the parts that are needed for growth.
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It seems funny to think that not growing can be a mechanism for survival. But if you’re a bacteria, and you can hang around long enough in an inactive, non-growing state, eventually your human host will stop taking antibiotics, they will disappear from your environment and you can go back to growing.

Disrupting the Replication of Bacteria

UW-Madison researchers develop novel method to find new antibiotics:

Filutowicz’s approach involves looking for new drugs that render bacteria harmless by blocking the replication of—and thus eliminating—some of their DNA.

Bacterial DNA comes in two forms: chromosomal DNA, which is required for life, and plasmid DNA, which is not. The nonessential plasmid DNA contains many undesirable bacterial genes, including those that confer antibiotic resistance or lead to the production of toxins.

Filutowicz is seeking antibiotics that would selectively disrupt the replication of plasmid DNA, so that when bacteria reproduce, they would produce plasmid-free offspring that are harmless or susceptible to traditional antibiotics. Such compounds could dramatically alter the character of some of our nastiest microbial adversaries.

Anti-microbial ‘paint’

anti-microbial ‘paint’ kills flu, bacteria

A new “antimicrobial paint” developed at MIT can kill influenza viruses that land on surfaces coated with it, potentially offering a new weapon in the battle against a disease that kills nearly 40,000 Americans per year. If applied to doorknobs or other surfaces where germs tend to accumulate, the new substance could help fight the spread of the flu, says Jianzhu Chen, MIT professor of biology.
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The “antimicrobial paint,” which can be sprayed or brushed onto surfaces, consists of spiky polymers that poke holes in the membranes that surround influenza viruses. Influenza viruses exposed to the polymer coating were essentially wiped out. The researchers observed a more than 10,000-fold drop in the number of viruses on surfaces coated with the substance.
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One of the benefits of the new polymer coating is that it is highly unlikely that bacteria will develop resistance to it, Klibanov said. Bacteria can become resistant to traditional antibiotics by adjusting the biochemical pathways targeted by antibiotics, but it would be difficult for bacteria to evolve a way to stop the polymer spikes from tearing holes in their membranes.

Bacteria in Food Increasingly Dangerous

Food-borne bacteria evolving, becoming more dangerous by Elizabeth Weise:

The evolution of ultra-dangerous versions of common food pathogens with which humans have coexisted for millennia. E. coli lives in the guts of most mammals. Almost all forms are harmless; some are actually necessary for health. It wasn’t until the 1970s that a deadly version — O157:H7 — emerged that causes kidney damage and death.

Two forms of the salmonella bacteria,Salmonella typhimurium and Salmonella newport, have evolved to resist most of the antibiotics that doctors are comfortable giving to children, says Patricia Griffin, who studies food-borne and diarrheal illnesses at the CDC.

Both are most common in cattle and other farm animals but are also turning up in fresh produce.

MRSA Vaccine Shows Promise

Superbug vaccine ‘shows promise’

A vaccine to guard against hospital superbug MRSA is a step closer, according to scientists. US researchers have developed a vaccine that protected mice from four potentially deadly strains of MRSA.
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The team looked for a vaccine using a technique called “reverse vaccinology”, which builds on recent genetics advances.

It involved sifting through the genome of Staphylococcus aureus to hunt for proteins on the microbe that might spark the body’s immune system into action, producing protection against the bacteria.

The team identified four proteins that prompted a strong immune response, making them good targets for vaccines.

More information on MRSA is available from the United States Center for Disease Control and Prevention.

Antibiotic Research

anti-microbial ‘grammar’ posits new language of healing

“In the last 40 years, there have been only two new classes of antibiotic drugs discovered and brought to the market,” said graduate student Christopher Loose, lead author of a paper on the work that appears in the Oct. 19 issue of Nature. “There is an incredible need to come up with new medicines.”
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focusing their attention on antimicrobial peptides, or short strings of amino acids. Such peptides are naturally found in multicellular organisms, where they play a role in defense against infectious bacteria.

See previous post on the paucity of new antibiotic discoveries

CDC Urges Increased Effort to Reduce Drug-Resistant Infections

The US Center for Disease Control has again urged hospitals to increase efforts to reduce drug-resistant infections. In 1972, only 2 percent of these types of bacteria were drug resistant. By 2004, 63 percent of these types of bacteria had become resistant to the antibiotics commonly used to treat them, and methicillin-resistant “staph” infections, often referred to as MRSA, are a growing problem. The CDC press release. This press release is focused on reducing the transmission of such dangers bacteria to patients. Other CDC efforts focus on improving the system to reduce the production of such virulent bacteria.

I know the Pittsburgh area has done a fair amount of work in the reduction of MRSA transmission. Several white papers on their efforts are available. A great PBS documentary covers this and other health care improvements.

Science Fair Project on Bacterial Growth on Packaged Salads

Recently we have all seen quite a few stories on – Tainted spinach: All bacteria may not come out in the wash. Last year a high school student did her science projected on the problem. Hillel Academy student first tested spinach for science fair by Stacey Dresner

“Last year I heard some rumors going around about how some people were getting sick and scientists thought that the illness was coming from these convenient packaged salads,” explained Kaili, now a ninth grader at the Hebrew High School of New England in West Hartford. “This caught my attention and I decided that I wanted to look more into the issue for my science fair project.”
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In her project, “Quantitative Analysis of Bacterial Growth on Packaged Salads and Effect on Antibiotic Resistance and Nutrient Content,” Kaili investigated several varieties of bagged salad greens.

She tested the bagged greens for bacteria content, and found “extensive growth of bacteria within 24 hours in the fresh “unwashed” samples.”

“I found the highest percents of bacteria in dark, leafy varieties such as spinach and Mediterranean” showing “a correlation between high levels of iron and high levels of bacteria.”

She washed the samples using different cleaning techniques n cleaning with sterile water, cooking with boiling water for five minutes, and using commercial cleaning rinse n water with a pinch of bleach. The only method that killed most of the bacteria was the commercial rinse. The others did not really inhibit bacterial growth.

Discoveries by Accident

‘Failed’ experiment produces a bacterial Trojan horse by Katie Weber. Interestingly the usefulness of Penicillin, the most popular bacteria fighting agent, was discovered by accident (and then a smart scientist learning from the accident and applying that knowledge to creating an incredibly useful medication).

As he was puzzling out why what should have been a routine procedure wouldn’t work, he made a discovery that led to the creation of a new biological tool for destroying bacterial pathogens – one that doesn’t appear to trigger antibiotic resistance.

The discovery also led to the startup of a promising new biotechnology firm that has already brought Wisconsin a dozen new, high-paying, highly skilled jobs.

This is yet another example of the power of scientists and engineers to boost the economy and society at large.