Posts about Antibiotics

Disrupting Bacterial Communication to Thwart Them

Interrupting Bacterial Chatter to Thwart Infection

To measure their own numbers, bacteria produce, release, and detect chemical signals called autoinducers. As a population of bacteria grows, it releases more autoinducer into its environment. When individuals detect that a threshold level of autoinducer is present, they change their behavior – by releasing a toxin, for example.

Bassler and her colleagues disrupted these lines of communication by interfering with molecules called acyl-homoserine lactone (AHL) autoinducers, which drive quorum sensing among a kind of bacteria known as Gram-negative bacteria. Gram-negative bacteria include Pseudomonas, E. coli and Salmonella, and other disease-causing microbes. In the study, the team focused on Chromobacterium violaceum, which rarely infects human, but can be lethal to other organisms. C. violaceum lends itself to studies of quorum sensing because it produces a readily detected, bright purple dye when it detects that its population has reached a critical mass.

The experiment shows that interfering with quorum sensing may provide an alternative to traditional antibiotics, Bassler says, and circumvent the problem of resistance that antibiotics foster by killing off susceptible bacteria but allowing resistant ones to survive and propagate.

Related: Bacteria Communicate Using a Chemical Language (quorum sensing)Disrupting Bacteria Communication (2007)Electrolyzed Water Replacing Toxic Cleaning SubstancesGram-negative Bacteria Defy Drug Solutions

Bacteria Use Nitric Oxide to Resist Antibiotics

Scientists Discover Mechanism to Make Existing Antibiotics More Effective at Lower Doses

Eliminating this NO[nitric oxide]-mediated bacterial defense renders existing antibiotics more potent at lower, less toxic, doses. With infectious diseases the major cause of death worldwide, the study paves the way for new ways of combating bacteria that have become antibiotic resistant.

NO is a small molecule composed of one atom of oxygen and one of nitrogen. It was known as a toxic gas and air pollutant until 1987, when it was first shown to play a physiological role in mammals, for which a Nobel Prize was later awarded. NO has since been found to take part in an extraordinary range of activities including learning and memory, blood pressure regulation, penile erection, digestion and the fighting of infection and cancer. A few years ago, the Nudler’s group from NYU demonstrated that bacteria mobilize NO to defend against the oxidative stress. The new study from the same group supports the radical idea that many antibiotics cause the oxidative stress in bacteria, often resulting in their death, whereas NO counters this effect. This work suggests scientists could use commercially available inhibitors of NO-synthase, an enzyme producing NO in bacteria and humans, to make antibiotic resistant bacteria like MRSA and ANTHRAX more sensitive to available drugs during acute infection.

The study by Nudler and his colleagues was funded by a 2006 Pioneer Award from the National Institutes of Health in Bethesda, Maryland. The Pioneer Award, a $2.5 million grant over five years, is designed to support individual scientists of exceptional creativity who propose pioneering and possibly transforming approaches to major challenges in biomedical and behavioral research.

Related: Copper Doorknobs and Faucets Kill 95% of SuperbugsHow Bleach Kills BacteriaForeign Cells Outnumber Human Cells in Our BodiesBacteria Survive On All Antibiotic Diet

Waste Treatment Plants Result in Super Bacteria

Multiple antibiotic-resistant bacteria has emerged as one of the top public health issues worldwide in the last few decades as the overuse of antibiotics and other factors have caused bacteria to become resistant to common drugs. Chuanwu Xi‘s group chose to study Acinetobacter because it is a growing cause of hospital-acquired infections and because of its ability to acquire antibiotic resistance.

Xi said the problem isn’t that treatment plants don’t do a good job of cleaning the water—it’s that they simply aren’t equipped to remove all antibiotics and other pharmaceuticals entering the treatment plants.

The treatment process is fertile ground for the creation of superbugs because it encourages bacteria to grow and break down the organic matter. However, the good bacteria grow and replicate along with the bad. In the confined space, bacteria share resistant genetic materials, and remaining antibiotics and other stressors may select multi-drug resistant bacteria.

While scientists learn more about so-called superbugs, patients can do their part by not insisting on antibiotics for ailments that antibiotics don’t treat, such as a common cold or the flu, Xi said. Also, instead of flushing unused drugs, they should be saved and disposed of at designated collection sites so they don’t enter the sewer system.

The next step, said Xi, is to see how far downstream the superbugs survive and try to understand the link between aquatic and human superbugs. This study did not look past 100 yards.

Xi’s colleagues include visiting scholar Yongli Zhang; Carl Marrs, associate professor of public health; and Carl Simon, professor of mathematics.

Xi and colleagues found that while the total number of bacteria left in the final discharge effluent declined dramatically after treatment, the remaining bacteria was significantly more likely to resist multiple antibiotics than bacteria in water samples upstream. Some strains resisted as many as seven of eight antibiotics tested. The bacteria in samples taken 100 yards downstream also were more likely to resist multiple drugs than bacteria upstream.

Full press release

Related: How Bleach Kills BacteriaSuperbugs, Deadly Bacteria Take HoldBacteria Race Ahead of DrugsNew Family of Antibacterial Agents Discovered

Scientists Target Bacteria Where They Live

Scientists Learning to Target Bacteria Where They Live

Scientists have learned that bacteria that are vulnerable when floating around as individual cells in what is known as their “planktonic state” are much tougher to combat once they get established in a suitable place — whether the hull of a ship or inside the lungs — and come together in tightly bound biofilms. In that state, they can activate mechanisms like tiny pumps to expel antibiotics, share genes that confer protection against drugs, slow down their metabolism or become dormant, making them harder to kill.

The answer, say researchers, is to find substances that will break up biofilms.

Melander said “a throwaway sentence in an obscure journal” — the Bulletin of the Chemical Society of Japan — gave them another clue. They isolated a compound from the sponge that disperses biofilms and figured out how to synthesize it quickly and cheaply.

But dispersing biofilms without understanding all the ramifications could be a “double-edged sword,” Romeo warned, because some bacteria in a biofilm could wreak worse havoc once they disperse.

“Simply inducing biofilm dispersion without understanding exactly how it will impact the bacterium and host could be very dangerous, as it might lead to spread of a more damaging acute infection,” he said.

Related: Entirely New Antibiotic DevelopedSoil Could Shed Light on Antibiotic ResistanceHow Antibiotics Kill Bacteria

Electrolyzed Water Replacing Toxic Cleaning Substances

Simple elixir called a ‘miracle liquid’

The stuff is a simple mixture of table salt and tap water whose ions have been scrambled with an electric current. Researchers have dubbed it electrolyzed water

Used as a sanitizer for decades in Russia and Japan, it’s slowly winning acceptance in the United States. A New York poultry processor uses it to kill salmonella on chicken carcasses. Minnesota grocery clerks spray sticky conveyors in the checkout lanes. Michigan jailers mop with electrolyzed water to keep potentially lethal cleaners out of the hands of inmates.

In Santa Monica, the once-skeptical Sheraton housekeeping staff has ditched skin-chapping bleach and pungent ammonia for spray bottles filled with electrolyzed water to clean toilets and sinks. “I didn’t believe in it at first because it didn’t have foam or any scent,” said housekeeper Flor Corona. “But I can tell you it works. My rooms are clean.”

It turns out that zapping salt water with low-voltage electricity creates a couple of powerful yet nontoxic cleaning agents. Sodium ions are converted into sodium hydroxide, an alkaline liquid that cleans and degreases like detergent, but without the scrubbing bubbles. Chloride ions become hypochlorous acid, a potent disinfectant known as acid water.

“It’s 10 times more effective than bleach in killing bacteria,” said Yen-Con Hung, a professor of food science at the University of Georgia-Griffin, who has been researching electrolyzed water for more than a decade. “And it’s safe.”

There are drawbacks. Electrolyzed water loses its potency fairly quickly, so it can’t be stored long. Machines are pricey and geared mainly for industrial use. The process also needs to be monitored frequently for the right strength.

Very cool use of science: providing a green cleaning agent that is effective.

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Gram-negative Bacteria Defy Drug Solutions

Deadly bacteria defy drugs, alarming doctors by Mary Engel

Acinetobacter doesn’t garner as many headlines as methicillin-resistant Staphylococcus aureus, the dangerous superbug better known as MRSA. But a January report by the Infectious Diseases Society of America warned that drug-resistant strains of Acinetobacter baumannii and two other microbes — Pseudomonas aeruginosa and Klebsiella pneumoniae — could soon produce a toll to rival MRSA’s.

The three bugs belong to a large category of bacteria called “gram-negative” that are especially hard to fight because they are wrapped in a double membrane and harbor enzymes that chew up many antibiotics. As dangerous as MRSA is, some antibiotics can still treat it, and more are in development, experts say.

But the drugs once used to treat gram-negative bacteria are becoming ineffective, and finding effective new ones is especially challenging.

For the most part, gram-negative bacteria are hospital scourges — harmless to healthy people but ready to infect already-damaged tissue. The bacteria steal into the body via ventilator tubes, catheters, open wounds and burns, causing pneumonia, urinary tract infections, and bone, joint and bloodstream infections.

Pseudomonas is widely found in soil and water, and rarely causes problems except in hospitals.

Related: Superbugs – Deadly Bacteria Take HoldCDC Urges Increased Effort to Reduce Drug-Resistant InfectionsMRSA Blows Up Defender Cellsposts on antibiotics

New Family of Antibacterial Agents Discovered

Bacteria continue to gain resistance to commonly used antibiotics. In this week’s JBC, one potential new antibotic has been found in the tiny freshwater animal Hydra.

The protein identified by Joachim Grötzinger, Thomas Bosch and colleagues at the University of Kiel (Germany), hydramacin-1, is unusual (and also clinically valuable) as it shares virtually no similarity with any other known antibacterial proteins except for two antimicrobials found in another ancient animal, the leech.

Hydramacin proved to be extremely effective though; in a series of laboratory experiments, this protein could kill a wide range of both Gram-positive and Gram-negative bacteria, including clinically-isolated drug-resistant strains like Klebsiella oxytoca (a common cause of nosocomial infections). Hydramacin works by sticking to the bacterial surface, promoting the clumping of nearby bacteria, then disrupting the bacterial membrane.

Grötzinger and his team also determined the 3-D shape of hydramacin-1, which revealed that it most closely resembled a superfamily of proteins found in scorpion venom; within this large group, they propose that hydramacin and the two leech proteins are members of a newly designated family called the macins.

Source: American Society for Biochemistry and Molecular Biology

Related: Entirely New Antibiotic Developed (platensimycin)Bacteria Race Ahead of DrugsHow Bleach Kills BacteriaAntibacterial Products May Do More Harm Than Good

Evolution, Methane, Jobs, Food and More

photo of sunset on Mars
Photo from May 2005 by NASA’s Mars Exploration Rover Spirit as the Sun sank below the rim of Gusev crater on Mars.

Science Friday is a great National Public Radio show. The week was a great show covering Antimicrobial Copper, Top Jobs for Math and Science, Human-Driven Evolution, Methane On Mars, Fish with Mercury and more. This show, in particular did a great job of showing the scientific inquiry process in action.

“Fishing regulations often prescribe the taking of larger fish, and the same often applies to hunting regulations,” said Chris Darimont, one of the authors of the study. “Hunters are instructed not to take smaller animals or those with smaller horns. This is counter to patterns of natural predation, and now we’re seeing the consequences of this management.” Darimont and colleagues found that human predation accelerated the rate of observable trait changes in a species by 300 percent above the pace observed within purely natural systems, and 50 percent above that of systems subject to other human influences, such as pollution

Very interesting stuff, listen for more details. A part of what happens is those individuals that chose to focus on reproducing early (instead of investing in growing larger, to reproduce later) are those that are favored (they gain advantage) by the conditions of human activity. I am amazed how quickly the scientists says the changes in populations are taking place.

And Methane On Mars is another potentially amazing discovery. While it is far from providing proof of live on Mars it is possibly evidence of life on Mars. Which would then be looked back on as one of the most important scientific discoveries ever. And in any even the podcast is a great overview of scientists in action.

This week astronomers reported finding an unexpected gas — methane — in the Martian atmosphere. On Earth, a major source of methane is biological activity. However, planetary scientists aren’t ready to say that life on Mars is to blame for the presence of the gas there, as geochemical processes could also account for the finding. The find is intriguing especially because the researchers say they have detected seasonal variations of methane emissions over specific locations on the planet.

Martian Methane Reveals the Red Planet is not a Dead Planet
The Mars Methane Mystery: Aliens At Last?

Related: Mars Rover Continues ExplorationCopper Doorknobs and Faucets Kill 95% of SuperbugsViruses and What is Lifeposts on evolutionScience and Engineering Link Directory

How Antibiotics Kill Bacteria

How Antibiotics Kill Bacteria

Since the first antibiotics reached the pharmacy in the 1940s, researchers discovered that they target various pieces of machinery in bacterial cells, disrupting the bacteria’s ability to build new proteins, DNA, or cell wall. But these effects alone do not cause death, and a complete explanation of what actually kills bacteria after they are exposed to antibiotics has eluded scientists.

The group found that all bactericidal antibiotics, regardless of their initial targets inside bacteria, caused E. coli to produce unstable chemicals called hydroxyl radicals. These compounds react with proteins, DNA, and lipids inside cells, causing widespread damage and rapid death for the bacteria.

With the results of these two experiments, the researchers were able to identify three major processes implicated in gentamicin-induced cell death: protein transport, a stress response triggered by abnormal proteins in the cell membrane, and a metabolic stress response.

Related: How Bleach Kills BacteriaBacteria Survive On All Antibiotic DietSoil Could Shed Light on Antibiotic ResistanceAntibiotics Too Often Prescribed for Sinus Woes

Yogurts Used to Combat Superbugs

Yoghurts used to combat superbugs

Dieticians at Addenbrooke’s have said evidence suggested the yoghurt might cut the risk of contracting C.diff. Caroline Heyes, dietetic services manager at Addenbrooke’s hospital, said: “Probiotic yoghurts may play a role in preventing C.difficile infection so we have been running a pilot on three of the care of the elderly wards for six months.

“We can’t say for sure how much of that benefit is down to the yoghurt and how much they are down to a whole range of infection control procedures that the hospital has in place such as the deep cleaning programme, the bare-below-the-elbow programme, and the increased isolation procedures,” Ms Heyes said.

Related: Bacterial Evolution in YogurtBeneficial Bacteria

Copper Doorknobs and Faucets Kill 95% of Superbugs

Copper door handles and taps kill 95% of superbugs in hospitals

A study found that copper fittings rapidly killed bugs on hospital wards, succeeding where other infection control measures failed.

It is thought the metal ‘suffocates’ germs, preventing them breathing. It may also stop them from feeding and destroy their DNA. Lab tests show that the metal kills off the deadly MRSA and C difficile superbugs. It also kills other dangerous germs, including the flu virus and the E coli food poisoning bug.

Researcher Professor Peter Lambert, of Aston University, Birmingham, said: ‘The numbers decreased always on copper but not on the steel surfaces.’

The healing power of copper has been recognised for thousands of years. More than 4,000 years ago, the Egyptians used it to sterilise wounds and drinking water and the Aztecs treated skin conditions with the metal. The ancient Greeks also knew of its benefits. Hippocrates, sometimes called ‘the father of medicine’, noted that it could be used to treat leg ulcers.

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