SLU researcher discovers new information about how antibiotics stop staph infections

In research published in Proceedings of the National Academy of Sciences, assistant professor of biochemistry and molecular biology at Saint Louis University Mee-Ngan F. Yap, Ph.D., discovered new information about how antibiotics like azithromycin stop staph infections, and why staph sometimes becomes resistant to drugs.

Her evidence suggests a universal, evolutionary mechanism by which the bacteria eludes this kind of drug, offering scientists a way to improve the effectiveness of antibiotics to which bacteria have become resistant.

Staphylococcus aureus (familiar to many as the common and sometimes difficult to treat staph infection) is a strain of bacteria that frequently has become resistant to antibiotics, a development that has been challenging for doctors and dangerous for patients with severe infections.

Yap and her research team studied staph that had been treated with the antibiotic azithromycin and learned two things: One, it turns out that the antibiotic isn't as effective as was previously thought. And two, the process that the bacteria use to evade the antibiotic appears to be an evolutionary mechanism that the bacteria developed in order to delay genetic replication when beneficial.

The team studied the way antibiotics work within the ribosome, the site where bacteria translates the genetic codes into protein. When the bacteria encounter a potential problem in copying its genetic material, as posed by an antibiotic, it has a mechanism to thwart antibiotic inhibition by means of "ribosome stalling" that is mediated by special upstream peptide elements.

Ref  http://www.pnas.org/content/111/43/15379.abstract?sid=94feec3e-058d-4239-97fb-bb9db8f148bb

SLU researcher discovers new information about how antibiotics stop staph infections

Promising discovery in fight against antibiotic-resistant bacteria .....

Researchers at  the  University  of British  Columbia  have identified a small molecule  that prevents  bacteria from forming into biofilms, a frequent cause of infections. The anti-biofilm peptide works on a range of bacteria including many that cannot be treated by antibiotics...

Hancock and his colleagues found that the peptide known as 1018  consisting of just 12 amino acids, the building blocks of protein  destroyed biofilms and prevented them from forming.

Bacteria are generally separated into two classes, Gram-positives and Gram-negatives, and the differences in their cell wall structures make them susceptible to different antibiotics. 1018 worked on both classes of bacteria as well as several major antibiotic-resistant pathogens, including Pseudomonas aeruginosa, E. coli and MRSA.

"Antibiotics are the most successful medicine on the planet. The lack of effective antibiotics would lead to profound difficulties with major surgeries, some chemotherapy treatments, transplants, and even minor injuries," says Hancock. "Our strategy represents a significant advance in the search for new agents that specifically target bacterial biofilms."

Promising discovery in fight against antibiotic-resistant bacteria 

Multitarget TB drug could treat other diseases, evade resistance -- ScienceDaily

A drug under clinical trials to treat tuberculosis could be the basis for a class  of broad-spectrum drugs that act against various bacteria, fungal infections and parasites, yet evade resistance, according to a study. The team determined the different ways the drug SQ109 attacks the tuberculosis bacterium, how the drug can be tweaked to target other pathogens from yeast to malaria  and how targeting multiple pathways reduces the probability of pathogens becoming resistant.

Led by U. of I. chemistry professor Eric Oldfield, the team determined the different ways the drug SQ109 attacks the tuberculosis bacterium, how the drug  can be tweaked to target other pathogens from yeast to malaria -- and how targeting multiple pathways reduces the probability of pathogens becoming resistant. SQ109 is made by Sequella Inc., a pharmaceutical company. 

"Drug resistance is a major public health threat," Oldfield said. "We have to make new antibiotics, and we have to find ways to get around the resistance problem. And one way to do that is with multitarget drugs. Resistance in many cases arises because there's a specific mutation in the target protein so the drug will no longer bind. Thus, one possible route to attacking the drug resistance problem will be to devise drugs that don't have just one target, but
two or three targets."

Oldfield read published reports about SQ109 and realized that the drug would likely be multifunctional because it had chemical features similar to those found in other systems he had investigated. The original developers had identified one key action against tuberculosis -- blocking a protein involved in building the cell wall of the bacterium -- but conceded that the drug could have other actions within the cell as well since it was found to kill other bacteria and
fungi that lacked the target protein. Oldfield believed he could identify those actions  and perhaps improve upon SQ109. 

"I was reading Science magazine one day and saw this molecule, SQ109, and I thought, that looks a bit like molecules we've been studying that have multiple targets," Oldfield said. "Given its chemical structure, we thought that some of the enzymes that we study as cancer and antiparasitic drug targets also could be SQ109 targets. We hoped that we could make some analogs that would be more potent against tuberculosis, and maybe even against parasites.

More : http://pubs.acs.org/doi/abs/10.1021/jm500131s

Multitarget TB drug could treat other diseases, evade resistance

Supramolecular high-aspect ratio assemblies with strong antifungal activity : Nature Communications : Nature Publishing Group

Efficient and pathogen-specific antifungal agents are required to mitigate drug resistance problems. Here we present cationic small molecules that exhibit excellent microbial selectivity with minimal host toxicity. Unlike typical cationic polymers possessing molecular weight distributions, these compounds have an absolute molecular weight aiding in isolation and characterization. However, their specific molecular recognition motif (terephthalamide-bisurea) facilitates spontaneous supramolecular self-assembly manifesting in several polymer-like properties. Computational modelling of the terephthalamide-bisurea structures predicts zig-zag or bent arrangements where distal benzyl urea groups stabilize the high-aspect ratio aqueous supramolecular assemblies. These nanostructures are confirmed by transmission electron microscopy and atomic force microscopy. Antifungal activity against drug-sensitive and drug-resistant strains with in vitro and in vivo biocompatibility is observed. Additionally, despite repeated sub-lethal exposures, drug resistance is not induced. Comparison with clinically used amphotericin B shows similar antifungal behaviour without any significant toxicity in a C. albicansbiofilm-induced mouse keratitis model.

Supramolecular high-aspect ratio assemblies with strong antifungal activity : Nature Communications : Nature Publishing Group