Such a test could spare a subgroup of people who need the surgery a time-consuming and costly treatment for infection, while helping to ensure that people who need the procedure get it. The test is described in the March issue of the Journal of Bone and Joint Surgery.
Each year, hundreds of thousands of joint replacement surgeries are performed in this country. And each year, thousands of them must be revised (the prosthetic joint must be removed and replaced) due to severe pain and swelling. These symptoms are often due to infection, says Rocky S. Tuan, Ph.D., chief of NIAMS' Cartilage Biology and Orthopaedics Branch.
The standard treatment for suspected infection is to remove the joint prosthesis and replace it with a spacer that has been impregnated with antibiotics. After about six weeks, patients must undergo another surgery to remove the spacer. Only then can the surgeon implant the new prosthesis.
The problem with this approach is that confirming the presence of infection-causing bacteria is an inexact science. Currently, doctors check for infection by culturing a sample of the joint fluid. A positive culture confirms live bacteria, making spacer surgery a certainty. A negative culture, however, does not necessarily mean there is no infection. In fact, Tuan says that estimates of the false negative rate for joint cultures in revision surgeries range from 27 percent to 50 percent. But because failure to treat an infected joint could lead to severe infection and limb amputation, spacer surgery is sometimes performed for safety's sake even when infection test results are inconclusive.
To get around the false-negative problem, Tuan and his colleagues developed a way to test for joint infections using polymerase chain reaction (PCR), which detects the presence of bacterial DNA. However, this approach proved to have pitfalls, too. It picked up all bacteria — even dead or dying bacteria that cannot perpetuate infection — thereby giving false positives.
Tuan says this new problem led them to expand their PCR approach by testing for bacterial messenger ribonucleic acid (mRNA). "When bacteria are dying, their mRNA is one of the first things to go," he says. As a result, the researchers hypothesized that a good mRNA test would not only detect bacteria, but would likely tell them if any bacteria they detected were still viable. Unlike DNA, mRNA is not directly quantifiable by known techniques, so the mRNA test that Tuan's group developed employs a process called reverse transcription PCR (RT-PCR) to convert the mRNA into DNA for measurement.
Tuan's group tested the validity of their new method by introducing bacteria into infection-free joint fluid to simulate infection. To ensure that the bacteria were indeed present, they used the PCR test, which accurately showed the amount of bacterial DNA. The researchers then treated the joint fluid cultures with potent antibiotics designed to kill off the bacteria. As expected, the PCR-DNA test still showed that the fluid contained plenty of bacteria, but when the group analyzed the cultures with the RT-PCR test for mRNA, they found that the viable bacteria population was declining.
Now Tuan's team is recruiting 50 people who need joint revision for a clinical trial that will involve testing patients' joint fluid for bacteria and then following them for 6 months to a year after surgery. They hope that the results from this study will validate the protocol to identify or rule out infections before a person begins a surgical revision.
Tuan would like to be able to tell patients who need infection treatment, "There is a really bad infection and we know what to do."
"But we also want to tell the person without infection that it's O.K. to put in a revision joint. That saves the spacer, the additional surgery and its associated risk, and 6 weeks of being laid up," Tuan says.
The mission of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the Department of Health and Human Services' National Institutes of Health (NIH), is to support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases; the training of basic and clinical scientists to carry out this research; and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at http://www.niams.nih.gov.
The National Institutes of Health (NIH) — The Nation's Medical Research Agency — includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.Reference:
Finding new clues to brain cancer treatment
21.02.2020 | Case Western Reserve University
UIC researchers find unique organ-specific signature profiles for blood vessel cells
18.02.2020 | University of Illinois at Chicago
The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.
Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...
Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.
Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...
Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices
The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...
Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.
Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.
After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.
"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.
12.02.2020 | Event News
16.01.2020 | Event News
15.01.2020 | Event News
21.02.2020 | Medical Engineering
21.02.2020 | Health and Medicine
21.02.2020 | Physics and Astronomy