Researchers find a new method of detecting microbial pathogens in patients with blood infections



ANI |
Updated:
December 04, 2022 05:03 ist

London [UK]Dec 4 (ANI): Using the Wyss Institute’s FcMBL broad-spectrum pathogen capture technology, researchers have redesigned the method for detecting microbial pathogens in blood samples from pediatric sepsis patients.
The development enables reliable detection of pathogens with sensitivity and speed never seen before, and can greatly improve therapeutic outcomes for pediatric and elderly patients with bloodstream infections (BSIs) and sepsis.
The research led by researchers at the Great Ormond Street Institute of Child Health (GOSH), London and includes researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University and BOA Biomedical in Cambridge and the findings were published in PLoS ONE.
BSIs with various microbial pathogens can quickly escalate to life-threatening sepsis when the body is overwhelmed by multiplying invaders and shuts down the functions of your organs. In 2017, there were 48.9 million cases and 11 million sepsis-related deaths worldwide. Importantly, almost half of all sepsis cases globally occurred among children, with an estimated 20 million cases and 2.9 million deaths globally in children under five years of age.
To prevent BSIs from progressing to full-blown sepsis, the bacterial or fungal species causing the infection must be identified as quickly as possible. Only then can antibacterial or antifungal treatments tailored to the pathogens be applied in time. The conventional method used in clinical laboratories to identify causative pathogen species is long and laborious, requiring two time-consuming culture steps taking at least 1-3 days to complete.
“For all patients with sepsis, their chances of survival are dramatically reduced the longer it takes to identify the pathogens causing the infection and thus receive the most promising antimicrobial treatment,” said Nigel Klein, MD, Ph.D. ., pls. , professor of infectious diseases and immunology at GOSH and lead author of the study. “At Great Ormond Street Hospital we have been working to demonstrate both the importance of rapid diagnosis and the fact that with innovative approaches we can identify the causative organism within 40 minutes to six hours. Compared to adult patients, sepsis in infants and children progresses much faster and therefore there is a real need for diagnostic methods that support early detection.Accurate diagnosis is even more important due to the availability of only small volumes of blood from pediatric patients, which can make it difficult sampling”.
In 2020, lead authors Klein and Elaine Cloutman-Green, Ph.D., a consulting clinical scientist and infection control physician at GOSH, began collaborating with lead scientist Michael Super, Ph.D. and Founding Director Donald Ingber, MD, Ph.D. at Harvard’s Wyss Institute to solve this problem. “Based on our previous success with FcMBL in isolating pathogens from joints, as well as from bovine and human blood with extraordinary efficiencies, we hypothesized that constructing FcMBL-mediated pathogen capture in a modified clinical blood culture protocol could shorten the time and reduce the size of patient samples needed to obtain the same results as time-consuming blood culture protocols provide,” Super said.

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In the pathogen identification process currently carried out in clinical settings, blood samples are first added to bottles containing liquid media in which infectious microbes, if present, are amplified to a certain density. The amplified microbes are then grown on solid media as isolated colonies whose constituent cells can eventually be identified with a highly sensitive, yet rapid and relatively inexpensive analytical method known as MALDI-TOF mass spectrometry (MS). “In fact, isolating infectious microbes directly from FcMBL-grown fluid blood cultures makes them available for MALDI-TOF MS analysis much sooner,” Super added.
FcMBL is the key component of a broad-spectrum pathogen capture technology. It consists of a genetically modified human immune protein called mannose-binding lectin (MBL) that is fused with the Fc fragment of an antibody molecule to produce the resulting FcMBL protein. In this configuration, the MBL portion of the FcMBL can capture more than 100 [CHECK WITH MIKE] different microbial species with high efficiency, including virtually all bacterial and fungal pathogens that cause sepsis. The Fc portion of FcMBL can be used to attach to magnetic beads, allowing captured pathogens to be rapidly extracted from patient samples and liquid blood cultures.
In the early stages of the project, Wyss’s team provided FcMBL coupled with purified beads to the GOSH team, which had access to blood samples from pediatric patients at the hospital. In later stages, sepsis and infectious disease company BOA Biomedical, co-founded by Super and Ingber to commercialize the Wyss Institute’s FcMBL technology, provided the FcMBL reagent and critical expertise for the project. Meanwhile, BOA Biomedical developed the manufacturing capabilities for FcMBL that are required by the US Food and Drug Administration (FDA) and other federal health agencies to produce therapeutic and diagnostic products.
“Sepsis is the leading cause of death in hospitals, and promptly starting the correct antibiotic saves lives. Building on work originally developed at the Wyss Institute, BOA Biomedical’s revolutionary FcMBL technology helps quickly and accurately identify the pathogen that causes sepsis, ushering in a new era of antimicrobial therapy to help individual patients and curb society’s deadly antimicrobial resistance problem,” said Mike McCurdy, MD, BOA Biomedical’s chief medical officer.
In addition to using the gold standard two-step blood culture in combination with MALDI-TOF MS pathogen identification, the team also included Bruker Corporation’s MBT Sepsityper® kit for comparison. Launched on the market in 2021, the MBT Sepsityper® essentially eliminates the time-consuming second microbial culture step by lysing microbial cells from liquid culture and spinning the fragments in a centrifuge before analysis using MALDI-TOF mass spectrometry analysis. . Although it speeds up the overall diagnostic process, the MBT Sepsityper® method produces lower microbial detection rates than those obtained with the conventional culture method, meaning that it may still miss the pathogen causing the infection in a significant fraction of the cases. blood samples.
“Our FcMBL approach has opened up the opportunity to identify pathogenic organisms to guide treatment 24 to 48 hours earlier than would be possible using standard culture techniques. It has also allowed us to use this identification to make any ongoing cultures for susceptibility to antibiotics is better suited to the needs of the patient.This method is not tied to a specific platform or manufacturer and therefore we see clear potential for it to become a new standard processing step for clinical pathogen detection “Cloutman-Green said.
“The FcMBL method identified 94.1% of the microbial species found in clinical analysis of blood cultures using samples from 68 pediatric patients,” said first author Kerry Kite, who did her graduate work with Klein and Cloutman-Green. “We were able to identify more infectious species in positive fluid blood cultures using the FcMBL method than with the MBT Sepsityper® method (25 of 25 vs. 17 of 25), and this trend was even more pronounced for the common fungal pathogen Candida ( 24 of 24 against 9 of 24).” Candida species account for approximately 5% of all cases of severe sepsis and are the fourth most common pathogen isolated from the bloodstream of patients in the United States. Candida and other fungal infections not only require specific antifungal treatments, but distinguishing between the various types of fungal pathogens helps direct appropriate antimicrobial therapy. Specifically in neonatal intensive care units, Candida infections are a major cause of morbidity and mortality, killing up to 40% of babies and often causing neurodevelopmental impairments in those who survive.
“By continually adapting the powerful FcMBL pathogen capture technology to pressing and unmet diagnostic needs, such as the rapid diagnosis of sepsis in pediatric patients, we hope to profoundly alter the often bleak outlook for patients of all ages,” said Ingber. “Our ultimate goal is to be able to accurately and even more rapidly identify pathogens directly in small blood samples without the need for additional microbial cultures.” Ingber is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Children’s Hospital Boston, and the Hansjorg Wyss Professor of Bioinspired Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences. (AND ME)

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