Speeding up pathogen identification in infants and children with bloodstream infections – ScienceDaily


A collaborative team led by researchers from Great Ormond Street Institute of Child Health (GOSH) in London, including researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University and BOA Biomedical in Cambridge, has re-engineered the process of identifying microbial pathogens in the blood. Samples from pediatric sepsis patients using the Wyss Institute’s FcMBL broad-spectrum pathogen capture technique. This advance enables accurate pathogen detection through a combination of unprecedented sensitivity and speed, and could significantly improve clinical outcomes for children and the elderly with bloodstream infections (BSIs) and sepsis. The results are published in Plus one.

BSIs along with various microbial pathogens can rapidly escalate into life-threatening sepsis when the body is overwhelmed by proliferating invaders and halts the functions of its organs. In 2017, there were 48.9 million cases and 11 million deaths related to sepsis worldwide. Importantly, nearly half of all global sepsis cases occurred among children, with an estimated 20 million cases and 2.9 million global deaths among those under the age of five.

To prevent BSIs from progressing to full-blown sepsis, the bacterial or fungal species causing the infection must be identified as soon as possible. Only then can optimal antibacterial or antifungal treatments be applied at the right time. The traditional method used in clinical laboratories to identify pathogenic species is long and arduous, requiring two time-consuming culture steps that take at least 1 to 3 days to complete.

“For all patients with sepsis, their chances of survival are greatly reduced the longer it takes to identify the pathogen causing the infection and, therefore, They are receiving promising antimicrobial therapy.” , Professor of Infectious Diseases and Immunology at GOSH, and senior author on the study. “At GOSH we have worked to demonstrate the importance of rapid diagnosis and the fact that through innovative methods we can identify the causative organism within between 40 minutes and six hours. Compared to adult patients, sepsis in infants and young children progresses much faster and is therefore needed “This is true of diagnostic methods that support early detection. An accurate diagnosis is even more important because only small amounts of blood are available from pediatric patients which makes re-sampling difficult.”

In 2020, lead authors Klein and Elaine Klotman-Green, PhD, Consultant Clinical Scientist and Clinician in Infection Control at Great Ormond Street Hospital, began collaborating with Senior Specialist Scientist Michael Sober, PhD. and founding director Donald Ingber, MD, PhD. at Harvard University’s Wyss Institute to solve this problem. “Based on our previous success with FcMBL in isolating pathogens from joints as well as bovine and human blood with extraordinary efficiencies, we hypothesized that building FcMBL-mediated pathogen capture into a modified clinical blood culture protocol could shorten the time and reduce the volume of patient samples required to obtain patient samples,” Soper said. get the same results as time-consuming blood culture protocols provide.”

In the pathogen identification process currently performed in clinical settings, first, blood samples are added to bottles containing liquid media in which infectious microbes, if present, are amplified to a specific density. Next, the overgrown microbes are grown on solid media as isolated colonies whose constituent cells can eventually be identified by a highly sensitive, yet rapid and relatively inexpensive analytical method known as MALDI-TOF mass spectrometry (MS). “In fact, isolating infectious microbes directly from blood cultures cultured with FcMBL makes them available for very early MALDI-TOF MS analysis,” Sober added.

FcMBL is the key component of a broad spectrum pathogen capture technology. It consists of a transgenic human immune protein called mannose-binding lectin (MBL) that fuses to the Fc portion of an antibody molecule to produce the resulting FcMBL protein. In this configuration, the MBL portion of FcMBL can capture more than 100 [CHECK WITH MIKE] Highly efficient different microbial species, including all sepsis-causing bacterial and fungal pathogens. The Fc fragment of FcMBL can be used to attach to magnetic beads, allowing captured pathogens to be rapidly withdrawn from patient samples and liquid blood cultures.

In the early stages of the project, the double-bead-purified Wyss team provided FcMBL to the GOSH team, who had access to blood samples from pediatric patients in the hospital. In later stages, BOA Biomedical Sepsis and Infectious Diseases, which Super and Ingber co-founded to commercialize the Wyss Institute’s FcMBL technology, provided the FcMBL reagent and expertise critical to the project. Meanwhile, BOA Biomedical has developed manufacturing capabilities for the FcMBL required by the US Food and Drug Administration (FDA) and other federal health agencies to produce therapeutic and diagnostic products.

“Sepsis is the leading killer in hospitals, and the right antibiotic is quickly saving lives. Using work originally developed at the Wyss Institute, BOA Biomedical’s revolutionary FcMBL technology helps quickly and accurately identify the pathogen causing sepsis, ushering in a new era of targeting. Antimicrobial therapy is to help individual patients and reduce the potentially deadly problem of community antimicrobial resistance, said Mike McCurdy, 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 as a comparison. Coming to market in 2021, the MBT Sepsityper® essentially eliminates the time-consuming second microbial culture step by analyzing microbial cells from liquid culture and spinning the sections down in a centrifuge before being analyzed by MALDI-TOF mass spectrometry. Although it speeds up the overall diagnostic process, the MBT Sepsityper® method yields lower microbial detection rates than those obtained using the conventional culture method, which means that it may still fail to identify infectious pathogens in a significant portion of blood samples.

“Our FcMBL approach provided the opportunity to identify pathogenic organisms to direct treatment 24 to 48 hours earlier than would be possible with standard culture techniques. It also enabled us to use this identification to make any antibiotic-susceptible ongoing culture more detailed,” said Klotman-Green. “This method is not tied to a specific platform or manufacturer, and therefore we see clear potential to become a new standard processing step for detecting clinical pathogens.”

“The FcMBL method identified 94.1% of the microbial species found in clinical blood culture analysis with samples from 68 pediatric patients,” said first author Keri Kite, who did her graduate work with Klein and Klotman-Green. “We were able to identify more infectious species in positive liquid blood cultures with the FcMBL method than with the MBT Sepsityper® method (25 out of 25 vs 17 out of 25), and this trend was even more pronounced in the case of common fungal pathogens. candida (24 of 24 vs. 9 of 24). ” candida The species accounts for about 5% of all cases of severe sepsis and is the fourth most common pathogen isolated from the bloodstream of patients in the United States. Not only with infections candida Other fungi require specific antifungal therapies, and distinguishing between different types of pathogenic fungi helps guide appropriate antimicrobial therapy. specifically in neonatal intensive care units, candidaThe infection is a major cause of morbidity and mortality, killing up to 40% of infants and often causing neurodevelopmental impairment in those who survive.

“By continually adapting our powerful FcMBL pathogen capture technology to pressing and unmet diagnostic needs, such as rapid diagnosis of sepsis in pediatric patients, we hope to profoundly change the dismal outlook for patients of all ages,” Ingber said. “Our ultimate goal is to be able to accurately and quickly identify pathogens directly in small blood samples without the need for any additional germ cultures.” Ingber is too Yehuda Volkman is Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, W Hansjörg Wyss Professor of Bioengineering At Harvard College, John A. Paulson Engineering and Applied Sciences.

The study was authored by Sahl Loomba and Thomas Elliott at Imperial College London. Francis Youngblah, Lily Gates and Dagmar Alper at Great Ormond Street Hospital; George Downey and James Hill from BOA Biomedical; and Chanda Lightbawn and Thomas Doyle at the Wyss Institute. The authors were supported in their work by the clinical microbiology staff at GOSH, as well as Erika Tranfield with MALDI-TOF MS expertise. At GOSH, Simona Santojanni coordinated important project financial assistance from the Benecare Foundation and philanthropists Luca Albertini and Professor Pauline Barrio, as well as the Office of the Vice-Chancellor (Progress) at University College London. At the Wyss Institute, the study was funded by the Defense Advanced Research Projects Agency (DARPA) under Collaborative Agreement No. W911NF-16-C-0050, and the Wyss Institute’s Technology Translation Engine. Additional support was provided by BOA Biomedical.



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