Study findings could lead to new biomarker targets for clinical laboratories working to identify AMR bacteria
Reducing and managing antimicrobial resistance (AMR) is a major goal of researchers and health systems across the globe. And it is the job of microbiologists and clinical laboratories to identify microbes that are AMR and those which are not to guide physicians as to the most appropriate therapies for patients with bacterial infections.
Thus, a recent discovery by researchers at the Wesfarmers Centre of Vaccines and Infectious Diseases, a division of the Telethon Kids Institute at Perth Children’s Hospital in Australia, will be of interest to medical laboratory leaders. The researchers may have learned how some bacteria dodge antibiotics in the human body. Their findings could lead to new diagnostics and better patient outcomes.
The scientists published their findings in the journal Nature Communications titled, “Host-Dependent Resistance of Group A Streptococcus to Sulfamethoxazole Mediated by a Horizontally-Acquired Reduced Folate Transporter.”
“AMR is a silent pandemic of much greater risk to society than COVID-19. In addition to 10 million deaths per year by 2050, the WHO estimates AMR will cost the global economy $100 trillion if we can’t find a way to combat antibiotic failure,” Timothy Barnett, PhD (above), Deputy Director and head of the Strep A Pathogenesis and Diagnostics team at Wesfarmers Centre of Vaccines and Infectious Diseases, told News Medical. Additional research may provide new targets for clinical laboratories tasked with identifying antimicrobial resistant bacteria. (Photo copyright: University of Western Australia.)
Rendering an Antibiotic Ineffective
According to the University of Oxford, about 1.2 million people died worldwide in 2019 due to AMR, and antimicrobial-resistant infections played a role in as many as 4.95 million deaths that same year. The World Health Organization (WHO) declared AMR one of the top ten global public health threats facing humanity.
While investigating antibiotic sensitivity of Group A Streptococcus—a potentially deadly bacteria often detected on the skin and in the throat—the Australian researchers uncovered a mechanism that enabled bacteria to absorb nutrients from their human host and evade the antibiotic sulfamethoxazole, a commonly-prescribed treatment for Group A Strep.
“Bacteria need to make their own folates to grow and, in turn, cause disease. Some antibiotics work by blocking this folate production to stop bacteria growing and treat the infection,” Timothy Barnett, PhD, Deputy Director of the Wesfarmers Centre of Vaccines and Infectious Diseases and head of the Strep A Pathogenesis and Diagnostics team, told News Medical.
“When looking at an antibiotic commonly prescribed to treat Group A Strep skin infections, we found a mechanism of resistance where, for the first time ever, the bacteria demonstrated the ability to take folates directly from its human host when blocked from producing their own. This makes the antibiotic ineffective and the infection would likely worsen when the patient should be getting better,” he added.
According to their study, the researchers identified an energy-coupling (ECF) factor transporter S component gene that allows Group A Strep to acquire extracellular reduced folate compounds that likely “expands the substrate specificity of an endogenous ECF transporter to acquire reduced folate compounds directly from the host, thereby bypassing the inhibition of folate biosynthesis by sulfamethoxazole.”
The study indicates that this new form of antibiotic resistance is indistinguishable under traditional testing used in microbiology and clinical laboratories, which in turn makes it difficult for clinicians to prescribe effective antibiotics to fight an infection.
Understanding AMR before It Is Too Late
The research suggests that understanding AMR is more complicated and intricate than previously thought. Barnett and his team believe their discovery is just the “tip of the iceberg” and that it will prove to be a far-reaching issue across other bacterial pathogens in addition to Group A Strep.
In “CDC Ranks Two More Drug-Resistant Microbes as ‘Urgent Threat’ to Americans; Clinical Laboratories Are Advised to Increase Awareness of Antimicrobial Resistance,” Dark Daily covered a report by the federal Centers for Disease Control and Prevention (CDC) that calls attention the emergence of new antibiotic-resistant bacteria and fungi. In its report, the CDC lists 18 bacteria and fungi that pose either urgent, serious, or concerning threats to humans. It also placed one fungus and two bacteria on a “watch” list.
“Without antibiotics, we face a world where there will be no way to stop deadly infections, cancer patients won’t be able to have chemotherapy and people won’t have access to have life-saving surgeries,” Barnett told News Medical. “In order to preserve the long-term efficacy of antibiotics, we need to further identify and understand new mechanisms of antibiotic resistance, which will aid in the discovery of new antibiotics and allow us to monitor AMR as it arises.”
More research and clinical studies are needed before this discovery can become technology that clinical laboratories can use to test if microbes are AMR. The scientists at Wesfarmers Centre of Vaccines and Infectious Diseases are now developing testing methods to detect the presence of the antibiotic resistant mechanism and determine the best treatment options.
“It is vital we stay one step ahead of the challenges of AMR and, as researchers, we should continue to explore how resistance develops in pathogens and design rapid accurate diagnostic methods and therapeutics,” Kalindu Rodrigo, a PhD student in the Barnett lab and one of the authors of the study told News Medical. “On the other hand, equal efforts should be taken at all levels of the society including patients, health professionals, and policymakers to help reduce the impacts of AMR.”
—JP Schlingman
Related Information:
Australian Researchers Unearth a New Form of Antimicrobial Resistance
New Antimicrobial Resistance Mechanism Discovered in Streptococci
An Estimated 1.2 Million People Died in 2019 from Antibiotic-resistant Bacterial Infections