LOOKING TO CURE ANTIBIOTIC RESISTANCE

FROM:  NATIONAL SCIENCE FOUNDATION
Researcher studies how to prevent antibiotic resistance
Solution could be in bacterial protein called UmuD

The widespread and indiscriminate use of antibiotics has prompted many bacteria to mutate, an adaptation that often renders the drugs useless. The increasing threat of resistance worries infectious disease experts who fear that the era of public health successes brought by the introduction of antibiotics in the 1940s is seriously eroding, or soon even may be at an end.

But what if science could improve existing antibiotics in such a way as to not only destroy bacteria, but prevent them from mutating?

At least one research team, in seeking to better understand bacterial mutation, may provide scientific answers that ultimately could lead to thwarting the organisms' ability to mutate, thus blunting the increasing threat of antibiotic resistance.

"The idea would be a one-two punch," says Penny Beuning, an associate professor of chemistry and chemical biology at Northeastern University's college of science. "We need a good therapeutic target that will both kill the bacteria and prevent mutagenesis."

To be sure, the approach almost certainly is years away. Still, the National Science Foundation (NSF)-funded scientist thinks it may be possible. She and her colleagues are studying an important bacterial protein known as UmuD that regulates mutagenesis and may provide important clues about how to stop the process that eventually results in antimicrobial resistance.

Using the bacterium E. coli as a model, she has learned that UmuD interacts with the machinery that replicates DNA, and, when altered, may provide the switch that triggers mutation. UmuD exists in two forms, a full length version when first expressed, and later, if DNA is damaged, a much shorter form. It is this shorter version that allows bacteria to mutate.

Once there is DNA damage, "there is an SOS response, and the levels of some specific proteins go up," she says. "There is a massive stress response, and UmuD responds by cutting its arms off."

In cells where only the full-length version of the protein is present, the bacteria cannot mutate. "But when it forms its shorter self, the cells are mutable," she says.

The fact that UmuD is not present outside bacteria makes it a viable antibiotic target.

"The hope would be to find something that targets UmuD together with an existing antibiotic to prevent bacteria from mutating and developing a resistance to that particular drug," she says. "Among the things we have been looking at: how does UmuD work, and what controls the cleavage of the arms?"

Beuning is conducting her research under an NSF Faculty Early Career Development (CAREER) grant awarded in 2009 under the American Recovery and Reinvestment Act. The award supports junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research within the context of the mission of their organization. NSF is funding her work with $994,655 over five years.

Beuning specifically is looking at the cleavage process of UmuD using gel electrophoresis, which separates proteins according to size.

"UmuD is a small protein--139 amino acids--which loses 24 amino acids from the arm. So it goes from 139 to 115," she says. "We can observe this difference with electrophoresis, allowing us to determine how different conditions or other proteins might affect UmuD cleavage."

The team is studying different UmuD protein interactions in the lab, using biochemistry to see when and how different proteins bind to one another. Essentially "we light up the proteins and measure how they change when other proteins bind, using a method called FRET, which stands for fluorescence resonance energy transfer," she says.

"This measures energy transfer between two proteins using light emission," she adds. "The proteins have to be close to each other for energy transfer to occur, so it's a way of detecting whether two things bind to each other. People often call the technique a molecular ruler, because it can be used to measure precise distances, but we use it simply to measure proximity."

Using FRET, they discovered that UmuD prevents specific protein interactions in the replication process. That is, it stops or slows down replication by keeping two proteins that need to interact for replication from binding to each other. "Protein-protein interactions are generally hard to target with drugs, but the approach has some potential," she says.

They also use another technique that measures how floppy or flexible proteins are by putting them in heavy water and measuring how much heavier the protein gets as it trades its regular hydrogens with heavy hydrogens from the heavy water. "The floppier parts swap out the hydrogens faster than the less floppy parts," she says.

As part of the grant's education component, she has up to ten undergraduates--as well as local high school students and teachers--working in her research lab. Several students have worked in her lab as part of Northeastern's signature co-op program, in which students work full-time for six months in positions related to their career goals.

Also, she teaches an upper level chemical biology class to undergraduates, and created a lab research project for the students that takes place during half of the semester that actually involves them directly in her mutagenesis research.

"A lot of these students had not yet conducted any research, so they were really motivated by the idea of doing something that someone would use as part of a bigger project," she says. "Particularly at Northeastern, where co-op is such a large part of the culture, it is fun to take advantage of the laboratory as the ultimate in experiential education.”

-- Marlene Cimons, National Science Foundation
Investigators
Penny Beuning
Related Institutions/Organizations

CLAYS STUDIED FOR SUPERBUG KILLING PROPERTIES

 FROM:  NATIONAL SCIENCE FOUNDATION 

New answer to MRSA, other 'superbug' infections: clay minerals?

Researchers discover natural clay deposits with antibacterial properties

Superbugs, they're called: Pathogens, or disease-causing microorganisms, resistant to multiple antibiotics.

Such antibiotic resistance is now a major public health concern.

"This serious threat is no longer a prediction for the future," states a 2014 World Health Organization report, "it's happening right now in every region of the world and has the potential to affect anyone, of any age, in any country."

Could the answer to this threat be hidden in clays formed in minerals deep in the Earth?

Biomedicine meets geochemistry

"As antibiotic-resistant bacterial strains emerge and pose increasing health risks," says Lynda Williams, a biogeochemist at Arizona State University (ASU), "new antibacterial agents are urgently needed."

To find answers, Williams and colleague Keith Morrison of ASU set out to identify naturally-occurring antibacterial clays effective at killing antibiotic-resistant bacteria.

The scientists headed to the field--the rock field. In a volcanic deposit near Crater Lake, Oregon, they hit pay dirt.

Back in the lab, the researchers incubated the pathogens Escherichia coli and Staphylococcus epidermidis, which breeds skin infections, with clays from different zones of the Oregon deposit.

They found that the clays' rapid uptake of iron impaired bacterial metabolism. Cells were flooded with excess iron, which overwhelmed iron storage proteins and killed the bacteria.

"The ability of antibacterial clays to buffer pH also appears key to their healing potential and viability as alternatives to conventional antibiotics," state the scientists in a paper recently published in the journal Environmental Geochemistry and Health.

"Minerals have long had a role in non-traditional medicine," says Enriqueta Barrera, a program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research.

"Yet there is often no understanding of the reaction between the minerals and the human body or agents that cause illness. This research explains the mechanism by which clay minerals interfere with the functioning of pathogenic bacteria. The results have the potential to lead to the wide use of clays in the pharmaceutical industry."

Ancient remedies new again

Clay minerals, says Williams, have been sought for medicinal purposes for millennia.

Studies of French clays--green clays historically used in France in mineral baths--show that the clays have antibacterial properties. French green clays have been used to treat Mycobacterium ulcerans, the pathogen that causes Buruli ulcers.

Common in Africa, Buruli ulcers start as painful skin swellings. Then infection leads to the destruction of skin and large, open ulcers on arms or legs.

Delayed treatment--or treatment that doesn't work--may cause irreversible deformities, restriction of joint movement, widespread skin lesions, and sometimes life-threatening secondary infections.

Treatment with daily applications of green clay poultices healed the infections. "These clays," says Williams, "demonstrated a unique ability to kill bacteria while promoting skin cell growth."

Unfortunately, the original French green clays were depleted. Later testing of newer samples didn't show the same results.

Research on French green clays, however, spurred testing of other clays with likely antibacterial properties.

"To date," says Williams, "the most effective antibacterial clays are those from the Oregon deposit."

Samples from an area mined by Oregon Mineral Technologies (OMT) proved active against a broad spectrum of bacteria, including methicillin-resistant S. aureus (MRSA) and extended-spectrum beta-lactamase-resistant E. coli (ESBL).

What's in those rocks?

Understanding the geologic environment that produces antibacterial minerals is important for identifying other promising locations, says Williams, "and for evaluating specific deposits with bactericidal activity."

The OMT deposit was formed near volcanoes active over tens to hundreds of thousands of years. The Crater Lake region is blanketed with ash deposits from such volcanoes.

OMT clays may be 20 to 30 million years old. They were "born" eons before deposits from volcanoes such as Mt. Mazama, which erupted 7,700 years ago to form the Crater Lake caldera.

Volcanic eruptions over the past 70,000 or so years produced silica-rich magmas and hydrothermal waters that may have contributed to the Oregon deposit's antibacterial properties.

To find out, Williams and Morrison took samples from the main OMT open pit. Four types of rocks were collected: two blue clays, and one white and one red "alteration zone" rock from the upper part of the deposit.

Blue clay to the rescue

The OMT blue samples were strongly bactericidal against E. coli and S. epidermidis. The OMT white sample reduced the population of E. coli and S. epidermidis by 56 percent and 29 percent, respectively, but the red sample didn't show an antibacterial effect.

"We can use this information to propose the medicinal application of certain natural clays, especially in wound healing," says Williams.

Chronic, non-healing wounds, adds Morrison, are usually more alkaline (vs. acidic) than healthy skin. The pH of normal skin is slightly acidic, which keeps numbers of bacteria low.

"Antibacterial clays can buffer wounds to a low [more acidic] pH," says Williams, like other accepted chronic wound treatments, such as acidified nitrate. "The clays may shift the wound environment to a pH range that favors healing, while killing invading bacteria."

The Oregon clays could lead to the discovery of new antibacterial mechanisms, she says, "which would benefit the health care industry and people in developing nations. A low-cost topical antibacterial agent is quickly needed."

Answers to Buruli ulcers, MRSA and other antibiotic-resistant infections may lie not in a high-tech lab, but in ancient rocks forged in a hot zone: Oregon's once--and perhaps future--volcanoes.

-- Cheryl Dybas, NSF
Investigators
Lynda Williams
Related Institutions/Organizations
Arizona State University

NEW DRUG FUNDED TO FIGHT BIOTERRORISM, ANTIMICROBIAL-RESISTANT INFECTIONS

FROM:  HEALTH AND HUMAN SERVICES 
HHS funds drug for bioterrorism, antimicrobial-resistant infections

A new drug to help protect the public against two bioterrorism threats and provide a new option to treat antibiotic-resistant infections will advance in development under a public-private partnership, the U.S. Department of Health and Human Services’ Office of the Assistant Secretary for Preparedness and Response (ASPR) announced today.

“Antibiotic resistance adversely impacts our nation’s ability to respond effectively to a bioterrorism attack and to everyday public health threats,” said Robin Robinson, Ph.D., director of ASPR’s Biomedical Advanced Research and Development Authority (BARDA), which will oversee the project. “By partnering with industry to develop novel antimicrobial drugs against biothreats that also treat drug-resistant bacteria, we can address health security and public health needs efficiently.”

BARDA will support the development of Carbavance under a five-year cost-sharing agreement with Rempex Pharmaceuticals Inc. (a wholly owned subsidiary of The Medicines Company) in San Diego. The agreement includes an initial commitment from BARDA of $19.8 million and can be extended to provide up to $90 million over the five years.

The two bioterrorism threats are melioidosis and glanders. With existing antibiotic treatments, approximately 40 percent of people who become ill from these bacteria die from the illness, and up to 90 percent die if not treated.

Melioidosis, also called Whitmore's disease, can be mistaken for other diseases such as tuberculosis and common forms of pneumonia. The bacteria that cause melioidosis can be found in water and soil, and cause infection when a person touches or inhales the bacteria. The infection is common in parts of Southeast Asia and Australia.

Glanders is a respiratory disease that can affect people, although it is primarily found in animals. The bacteria that cause glanders can affect skin, blood, lungs, or muscles, and may be transmitted through direct contact with infected animals or by inhaling contaminated aerosols or dust.

Melioidosis and glanders can become resistant to existing antibiotics.

In addition to showing promise as a treatment for melioidosis and glanders in a bioterrorism event, Carbavance potentially could be used commercially to treat complicated urinary tract infections, hospital-acquired pneumonia, ventilator-acquired pneumonia, and carbapenem-resistant Enterobacteriaceae (CRE), all of which can be resistant to existing antibiotics.

CRE are a family of bacteria that have been called nightmare bacteria because the bacteria are resistant to all or nearly all antibiotics, kill up to half of people who get serious infections with them, and can spread their resistance to other bacteria. CRE infections have been detected in nearly every state, and the incidence has risen sharply over the past five years.

Patients whose care requires devices such as ventilators, urinary (bladder) catheters, or intravenous (vein) catheters, and patients who are taking long courses of certain antibiotics are most at risk for CRE infections.

The project includes preclinical and clinical studies, manufacture of enough of the drug for clinical studies, and other manufacturing-related activities needed to apply for U.S. Food and Drug Administration approval of the drug.

The project with Rempex is the latest in a BARDA program that supports development of broad-spectrum antimicrobials, technologies and platforms for biodefense needs that simultaneously address other public health challenges, such antibiotic-resistant infections.      

BARDA is seeking additional proposals for advanced development of novel antimicrobials to treat illness caused by biological threat agents and that also could address the growing threat of antimicrobial resistance. Proposals are accepted through the Broad Agency Announcement BARDA-BAA-13-100-SOL-00013 at https://www.fbo.gov.

BARDA utilizes a comprehensive, integrated portfolio approach to support the advanced research and development, innovation, acquisition, and manufacturing of vaccines, drugs, therapeutics, diagnostic tools, and non-pharmaceutical products for public health emergency threats. These threats include chemical, biological, radiological, nuclear threats, pandemic influenza, and emerging infectious diseases.

HHS is the principal federal agency for protecting the health of all Americans and providing essential human services, especially for those who are least able to help themselves. ASPR is an HHS leader in preparing the nation to respond to and recover from adverse health effects of emergencies, supporting communities’ ability to withstand adversity, strengthening health and response systems, and enhancing national health security.