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Portable System Uses Light to Diagnose Bacterial Infections Faster

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PAD system

Caption: PAD system. Left, four optical testing cubes (blue and white) stacked on the electronic base station (white with initials); right, a smartphone with a special app to receive test results transmitted by the electronic base station.
Credit: Park et al. Sci. Adv. 2016

Every year, hundreds of thousands of Americans acquire potentially life-threatening bacterial infections while in the hospital, nursing home, or other health-care settings [1]. Such infections can be caused by a variety of bacteria, which may respond quite differently to different antibiotics. To match a patient with the most appropriate antibiotic therapy, it’s crucial to determine as quickly as possible what type of bacteria is causing his or her infection. In an effort to improve that process, an NIH-funded team is working to develop a point-of-care system and smartphone app aimed at diagnosing bacterial infections in a faster, more cost-effective manner.

The portable new system, described recently in the journal Science Advances, uses a novel light-based method for detecting telltale genetic sequences from bacteria in bodily fluids, such as blood, urine, or drainage from a skin abscess. Testing takes place within small, optical cubes that, when placed on an electronic base station, deliver test results within a couple of hours via a simple readout sent directly to a smartphone [2]. When the system was tested on clinical samples from a small number of hospitalized patients, researchers found that not only did it diagnose bacterial infections about as accurately and more swiftly than current methods, but it was also cheaper. This new system can potentially also be used to test for the presence of antibiotic-resistant bacteria and contamination of medical devices.


Gene Expression Test Aims to Reduce Antibiotic Overuse

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Doctor with ER patient

Caption: Duke physician-scientist Ephraim Tsalik assesses a patient for a respiratory infection.
Credit: Shawn Rocco/Duke Health

Without doubt, antibiotic drugs have saved hundreds of millions of lives from bacterial infections that would have otherwise been fatal. But their inappropriate use has led to the rise of antibiotic-resistant superbugs, which now infect at least 2 million Americans every year and are responsible for thousands of deaths [1]. I’ve just come from the World Economic Forum in Davos, Switzerland, where concerns about antibiotic resistance and overuse was a topic of conversation. In fact, some of the world’s biggest pharmaceutical companies issued a joint declaration at the forum, calling on governments and industry to work together to combat this growing public health threat [2].

Many people who go to the doctor suffering from respiratory symptoms expect to be given a prescription for antibiotics. Not only do such antibiotics often fail to help, they serve to fuel the development of antibiotic-resistant superbugs [3]. That’s because antibiotics are only useful in treating respiratory illnesses caused by bacteria, and have no impact on those caused by viruses (which are frequent in the wintertime). So, I’m pleased to report that a research team, partially supported by NIH, recently made progress toward a simple blood test that analyzes patterns of gene expression to determine if a patient’s respiratory symptoms likely stem from a bacterial infection, viral infection, or no infection at all.

In contrast to standard tests that look for signs of a specific infectious agent—respiratory syncytial virus (RSV) or the influenza virus, for instance—the new strategy casts a wide net that takes into account changes in the patterns of gene expression in the bloodstream, which differ depending on whether a person is fighting off a bacterial or a viral infection. As reported in Science Translational Medicine [4], Geoffrey Ginsburg, Christopher Woods, and Ephraim Tsalik of Duke University’s Center for Applied Genomics and Precision Medicine, Durham, NC, and their colleagues collected blood samples from 273 people who came to the emergency room (ER) with signs of acute respiratory illness. Standard diagnostic tests showed that 70 patients arrived in the ER with bacterial infections and 115 were battling viruses. Another 88 patients had no signs of infection, with symptoms traced instead to other health conditions.


Creative Minds: Searching for Solutions to Chronic Infection

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Kyle R. Allison

Kyle R. Allison

If you or a loved one has ever struggled with a bacterial infection that seemed to have gone away with antibiotic treatment, but then came back again, you’ll probably be interested to learn about the work of Kyle Allison. What sometimes happens when a person has an infection—for instance, a staph infection of the skin—is that antibiotics kill off the vast majority of bacteria, but a small fraction remain alive. After antibiotic treatment ends, those lurking bacterial “persisters” begin to multiply, and the person develops a chronic infection that may be very difficult and costly to eliminate.

Unlike antibiotic-resistant superbugs, bacterial persisters don’t possess any specific genetic mutations that protect them against the killing power of one particular medication or another. Rather, the survival of these bacteria depends upon their ability to enter a dormant state that allows them to hang on in the face of antibiotic treatment. It isn’t clear exactly how the bugs do it, and that’s where Kyle’s work comes in.


Digging Up New Antibiotics

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iChip being removed from dirt

Caption: Microfluidic chip being used by scientists to search dirt for new sources of antibiotics.
Credit: Slava Epstein/Northeastern U.

Last fall, President Obama issued an Executive Order aimed at combating a growing public health threat: antibiotic-resistant infections that claim the lives of 23,000 Americans every year [1]. So, I’m pleased to report that biomedical research has made some exciting progress on this front with the discovery of what promises to be a powerful new class of antibiotic drugs—the first such discovery in more than 25 years.

There are two significant things about this feat. The first is that the new antibiotic, called teixobactin, not only has the ability to kill a wide range of infection-causing bacteria, but to kill them in a way that may greatly reduce the problem of resistance. The second is that researchers identified teixobactin using an ingenious approach that enhances our ability to search one of nature’s richest sources of potential antibiotics: soil [2, 3].


You Won’t Believe What’s In These Pills

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Fecal pills

Credit:: Hohmann lab

Clostridium difficile, or more commonly “C. diff,” is a nasty bacterium that claims the lives of 14,000 Americans every year. Most at risk are people with conditions requiring prolonged use of antibiotics, which have the unfortunate side effect of wiping out the natural, good bacteria in the colon—thus allowing bad bugs like C. diff to multiply unchecked. In many folks, C. diff infection can be treated by halting the original antibiotics and switching to other types of antibiotics. But for some people, that doesn’t work—C. diff is either resistant to treatment or makes a hasty comeback.

What’s to be done then? Well, researchers have known for some time that taking microbe-rich stool samples from healthy people and transplanting them into C. diff patients helps to improve their symptoms. The challenge has been figuring out a safe and effective way to do this that is acceptable to patients and doesn’t involve invasive procedures, such as colonoscopy or nasogastric tubes [1,2]. Could there be a simple solution? To put it more bluntly: what about poop pills?


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