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article imageEssential Science: Genetic test for antimicrobial resistance

By Tim Sandle     Mar 4, 2019 in Science
Scientists have put together a sensitive method to determine if bacteria carry a gene that can cause resistance to two common antibiotics. The test is rapid, and has been tested against ‘strep throat’ and other respiratory illnesses.
The new development comes the American University, and it takes the form of a rapid genetic test to differentiate which bacteria carry gene that causes resistance to two common antibiotics.
The research demonstrates that the new method functions as accurately as culture-based methods; however, unlike conventional methods, the result is delivered within a few minutes compared to the several days required with moist standard methods.
Antimicrobial resistance
Antimicrobial resistance is a phenomenon the occurs naturally as bacteria respond to various pressures within the environment. What is of concern is the worldwide acceleration of resistance. U.S. Centers for Disease Control and Prevention (CDC) data finds that many high-income countries are entering a “post antibiotic era.”
This key experiment shows the successful protection of a phage-sensitive bacterial strain against a ...
This key experiment shows the successful protection of a phage-sensitive bacterial strain against a virus. Top-right - bacteria growing in the absence of a virus; Top-left - holes in the culture caused by an infecting virus; Bottom - when equipped with specific CRISPR defense system components, the bacteria became resistant to the virus.
John van der Oost
One reason for the accelerated pace of resistance is down to the use and misuse of antimicrobial drugs, such as over-prescribing or the high levels that are used in agriculture.
Antimicrobial resistance often occurs due to gene transfer, meaning that some organisms of a population are resistant to a certain antimicrobial, whereas others are not. This can be a spontaneous or induced mutation.
New test
The new rapid method is designed to show whether or not a patient is carrying bacteria with the Macrolide efflux gene A - mef(A), which causes resistance to two common antibiotics: erythromycin and azithromycin. There is growing resistance to both of these antibiotics in the community.
Of these antibiotics, Azithromycin is used to commonly used to treat species of Streptococcus, which cause strep throat. Azithromycin has relatively broad but shallow antibacterial activity. It inhibits some Gram-positive bacteria, some Gram-negative bacteria, and many atypical bacteria.
A student of the Federal University of Rio de Janeiro works at a biology laboratory
A student of the Federal University of Rio de Janeiro works at a biology laboratory
Mauro Pimentel, AFP
Erythromycin is used for the treatment of a number of bacterial infections, such as respiratory tract infections and skin infections. The drug can be given intravenously and by mouth. It is derived from the bacterium Saccharopolyspora erythraea.
The new assay is a type of Recombinase Polymerase Amplification (RPA), which uses recombinase-primer complexes to identify and denature the genomic segment of interest, along with single-stranded DNA-binding proteins to stabilize the open DNA.
Commenting on the new assay, lead researcher John R. Bracht explains: “The test is able to detect the gene within 10 minutes of assay run-time. Standard antibiotic testing requires at least an overnight culture and often isn't performed in routine diagnostic work.”
He adds that instead “physicians guess which antibiotic to prescribe based on past experience and recommendations, and patients have to return if the treatment fails. We simplified the process of detecting antimicrobial resistance so a physician can determine whether or not a patient will be resistant to a prescribed drug while that patient is still in the waiting room. We think this is a game-changer for treating common illnesses."
The advantage of the new test is to help medics better assign medication on site, and to put in place improved point-of-care diagnostics.
Research paper
The research has been published in the journal BMC Infectious Diseases. The research paper is titled “Rapid molecular detection of macrolide resistance.”
Essential Science
File photo of soap and water
File photo of soap and water
This article is part of Digital Journal's regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we found out that the chemical triclosan, found in many household products, like toothpaste and mouthwash, has can inadvertently make some bacteria more resistant to antibiotics.
The week before we investigated a new technology that can convert plastic waste (the biggest environmental issue associated with modern society) into a clean fuel. This represents one useful application to address the global plastic crisis.
More about antimicrobials, Antibiotics, Microbiology
 
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