Biomarker for Pathogen That can Blind or Kill Healthy People Identified

Scientists have discovered several biomarkers that can accurately identify a drug-resistant pathogen that infects completely healthy people, can cause blindness in one day, and even lead to flesh-eating infections and death in just a few days. Thomas A Russo, a professor at University at Buffalo in the US, witnessed the first case of the hypervirulent Klebsiella pneumoniae seven years ago. There is no accurate method for distinguishing the rare but increasingly common hypervirulent strain from the classical strain of K pneumoniae, which causes infections in hospital settings. In a study, published in the Journal of Clinical Microbiology, researchers described several biomarkers that can accurately identify hypervirulent K. pneumoniae. “Presently, there is no commercially available test to accurately distinguish classical and hypervirulent strains. This research provides a clear roadmap as to how a company can develop such a test for use in clinical laboratories. It’s sorely needed,” said Russo.

A definitive diagnostic test would not only optimize patient care but would also allow researchers to perform epidemiologic surveillance to track how frequently the hypervirulent strain causes infection and how frequently it acquires antimicrobial resistance. While the assumption is that the pathogen spreads from person to person through food and water, the mode of transmission is unknown. Both strains of K pneumoniae can be deadly, but the classical strain is more likely to infect patients with underlying disease, or who are immune-compromised and hospitalized. By contrast, the hypervirulent strain can infect healthy, young people in the community, causing sudden, life-threatening complications, ranging from liver or brain abscesses to flesh-eating infections. While it is currently less likely to be antibiotic resistant, these strains continue to evolve. Classical strains are more likely to be antimicrobial resistant. “What’s increasingly concerning is the growing number of reports that describe strains of hypervirulent K pneumoniae that are antimicrobial resistant,” said Russo.

“A bug that’s both hypervirulent and challenging to treat is a bad combination,” he said. Since clinical laboratories have no test to detect the hypervirulent strain, it’s difficult, if not impossible, to properly diagnose it. The so-called string test, currently used in some cases to distinguish the classical and hypervirulent strains, is not consistently accurate. Hypervirulence of K pneumoniae is largely due to genes located on a large virulence plasmid, DNA that is independent from the chromosome. They hypothesized that some of these genes, including those producing iron-acquisition molecules called siderophores, might be good biomarkers. This proved to be the case. They also found that higher concentrations of siderophores predicted hypervirulence. They then validated the identified biomarkers in a mouse infection model. “The advantage of identifying these genetic biomarkers is that they can be developed into rapid nucleic acid tests, and if approved, would then provide clinicians with an accurate method to quickly determine if a patient is suffering from an infection due to the classical or hypervirulent strain,” Russo said. He added that such a test will not only benefit patients and possibly save lives but will also prove critical in learning more about hypervirulent K pneumoniae. – Business Standard

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