Tag Archives: Drugs

Microbiology

Experimental decoy provides long-term protection from SARS-Cov-2 infection

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Reviewed by Danielle Ellis, B.Sc.May 30 2023

An experimental “decoy” provided long-term protection from infection by the pandemic virus in mice, a new study finds.

Led by researchers at NYU Grossman School of Medicine, the work is based on how the virus that causes COVID-19, SARS-CoV-2, uses its spike protein to attach to a protein on the surface of the cells that line human lungs. Once attached to this cell surface protein, called angiotensin converting enzyme 2 (ACE2), the virus spike pulls the cell close, enabling the virus to enter the cell and hijack its machinery to make viral copies.

Earlier in the pandemic, pharmaceutical companies designed monoclonal antibodies to glom onto the spike and neutralize the virus. Treatment of patients soon after infection was successful in preventing hospitalization and death. However the virus rapidly evolved through random genetic changes (mutations) that altered the spike’s shape enough to evade even combinations of therapeutic monoclonal antibodies. Thus, such antibodies, which neutralized early variants, became about 300 times less effective against more recent delta and omicron variants.

Published online this week in the Proceedings of the National Academy of Sciences, the study describes an alternative approach from which the virus cannot escape. It employs a version of ACE2, the surface protein to which the virus attaches, which, unlike the natural, cell-bound version, is untethered from the cell surface. The free-floating “decoy” binds to the virus by its spikes so that it can no longer attach to ACE2 on cells in airways. Unlike the monoclonal antibodies, which are shaped to interfere with a certain spike shape, the decoy mimics the spike’s main target, and the virus cannot easily evolve away from binding to ACE2 and still invade cells.

Treatment with the decoy, either by injection or droplets in the nose, protected 100 percent of the study mice when they were infected in the lab with an otherwise lethal dose of SARS-CoV-2. The decoy lowered the virus load in the mice by 100,000-fold, while mice exposed to a non-active control treatment died. Decoy treatment of mice that were already infected with SARS-CoV-2 caused a rapid drop in viral levels and return to health. This suggests that the decoy could be effective as a therapy post-infection, similar to monoclonal antibodies, the researchers say.

What is remarkable about our study is that we delivered the decoy using a harmless, adeno-associated virus or AAV vector, a type of gene therapy that has been found in previous studies to be safe for use in humans. The viral vector instructs cells in the body to produce the decoy so that the mouse or person is protected long-term, without the need for continual treatment.”

Nathanial Landau, PhD, senior study author, professor, Department of Microbiology at NYU Langone Health

Administered with the vector, says Landau, the treatment caused cells, not only to make the decoy, but to continue making it for several months, and potentially for years.

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Importantly, vaccines traditionally include harmless parts of a virus they are meant to protect against, which trigger a protective immune response should a person later be exposed. Vaccines are less effective, however, if a person’s immune system has been compromised, by diseases like cancer or in transplant patients treated with drugs that suppress the immune response to vaccination. Decoy approaches could be very valuable for immunocompromised patients globally, adds Landau.

Future pandemics

For the new study, the research team made key changes to a free ACE2 receptor molecule, and then fused the spike-binding part of it to the tail end of an antibody with the goal of strengthening its antiviral effect. Attaching ACE2 to the antibody fragment to form what the team calls an “ACE2 microbody” increases the time that the molecule persists in tissues (its half-life). The combination also causes the molecules to form dimers, mirror-image molecular pairs that increase the strength with which the decoy attaches to the viral spike.

Whether administered via injection into muscle, or through droplets in the nasal cavity, the study’s AAV vectors provided mice with long-lasting protection COVID infection, including the current Omicron variants.

The approach promises to be effective even if another coronavirus, a type of virus common in birds and bats or apes, were to be transferred to humans in the future, an event termed “zoonosis.” As long as the future virus also uses ACE2 to target cells, the decoy would be ready for “off-the-shelf” soon after an outbreak. If the virus were to somehow switch its receptor a different protein on the surface of lung cells, the decoy could be modified to target the new virus, says Landau.

Along with Landau, the study authors were Takuya Tada and Julia Minnee in the Department of Microbiology at NYU Grossman School of Medicine. The study was supported by a grant from the National Institutes of Health.

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Source:

NYU Langone Health / NYU Grossman School of Medicine

Journal reference:

Tada, T., et al. (2023) Vectored immunoprophylaxis and treatment of SARS-CoV-2 infection in a preclinical model. PNAS. doi.org/10.1073/pnas.2303509120.

Microbiology

Antiviral drugs may be a new treatment strategy in the fight against Candida auris

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Reviewed by Megan Craig, M.Sc.May 25 2023

Antiviral drugs can make antifungals work again.

That, at its simplest, is the approach Mohamed Seleem’s lab at the Center for One Health Research has found may be a key treatment strategy in the battle against Candida auris, a frighteningly deadly fungal pathogen discovered in 2009 that is considered an urgent threat by the Centers for Disease Control and Prevention (CDC).

Candida auris, first discovered in Japan as an ear infection, has a staggering 60 percent mortality rate among those it infects, primarily people with compromised health in hospitals and nursing homes.

Recently, Seleem and Ph.D. students Yehia Elgammal and Ehab A. Salama published a paper in the American Society for Microbiology’s Antimicrobial Agents and Chemotherapy journal detailing the potential use of atazanavir, an HIV protease inhibitor drug, as a new avenue to improving the effectiveness of existing antifungals for those with a Candida auris infection.

A perfect storm of antimicrobial resistance, global warming and the COVID-19 pandemic has resulted in the rapid spread of Candida auris around the world, said Seleem, director of the center, a collaboration between the Virginia-Maryland College of Veterinary Medicine and the Edward Via College of Osteopathic Medicine.

We don’t have lots of drugs to use to treat fungal pathogens. We have only three classes of antifungal drugs. With a fungal pathogen, it’s often resistant to one class, but then we have two other options. What’s scary about Candida auris is it shows resistance to all three classes of the antifungal.

The CDC has a list of urgent threats, but on that list there is just one fungal pathogen, which is Candida auris. Because it’s urgent, we need to deal with it.”

Mohamed Seleem, the Tyler J. and Frances F. Young Chair in Bacteriology at Virginia Tech

Widespread use of fungicides in agriculture, in addition to the three classes of antifungal drugs used widely in medicine, has contributed to fungal pathogens developing more resistance, particularly Candida auris.

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Also, its rise has been linked to rising global temperatures and to easier spread through hospitals filled with COVID-19 patients in recent years during the global pandemic.

Atazanavir, an HIV protease inhibitor drug, has been found by Seleem’s lab to block the ability of Candida auris to excrete antifungals through its efflux pumps.

Think of a boat taking on water and hoses siphoning that water out of the boat to keep it afloat. Atazanavir stops up the hoses.

That allows the azole class of antifungal drugs to not be expelled as easily and perform better against Candida auris, the Seleem lab’s research has found.

The research on atazanavir builds on work three years ago by Seleem’s lab, then at Purdue University, finding potentially similar benefit in lopinavir, another HIV protease inhibitor.

HIV protease drugs are already in wide use among HIV patients, who can also be extra susceptible to Candida auris. Some HIV patients have likely been taking HIV protease drugs and azole-class antifungals in tandem for separate purposes, providing a potential source of already existing data that can be reviewed on whether those patients had Candida auris and what effects the emerging pathogen had on them.

Repurposing drugs already on the market for new uses can allow those treatments to reach widespread clinical use much more rapidly than would happen with the discovery of an entirely new drug, as existing drugs have already been tested and approved by the Food and Drug Administration and have years of further observation of effects in prescriptive use.

In 2022, the Center for One Health Research received a $1.9 million grant from the National Institutes of Health for the Seleem lab’s research on repurposing already approved drugs for treating gonorrhea.

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Source:

Virginia Tech

Microbiology

Honokiol inhibits replication of SARS-CoV-2 in several cell types

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Reviewed by Megan Craig, M.Sc.May 22 2023

A compound called honokiol, which is found in the bark of multiple species of magnolia tree, inhibits replication of SARS-CoV-2 virus in several types of cells, according to a team of researchers in the Netherlands. The research is published in Microbiology Spectrum, a journal of the American Society for Microbiology.

The researchers found that Honokiol inhibits replication of SARS-CoV-2 in several cell types, causing production of infectious SARS-CoV-2 particles in treated cells to fall to around 1,000th of the previous level.

The compound also inhibited replication of other highly pathogenic human coronaviruses, including MERS- and SARS-CoV.

This suggests that it has a broad spectrum of activity and would likely also inhibit novel coronaviruses that might emerge in the future.”

Martijn J. van Hemert, Ph.D., Associate Professor, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands

The motivation for the research was the lack of vaccines and treatments early in the pandemic, and the desire to be prepared for the next new coronavirus. To this end, van Hemert emphasized that his group, as well as others from around the world, responded to COVID-19 by testing many compounds for antiviral effects.

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“If honokiol can be developed into a drug, possibly in combination with other compounds, stockpiling it would help us to increase our preparedness for the emergence of the next coronavirus,” said van Hemert. “Broad-spectrum drugs could then be used to treat early patients and prevent spread, or they could be used prophylactically among healthcare workers, and in high-risk groups, such as among nursing home residents.”

Honokiol also has anti-inflammatory properties, van Hemert noted. That, he said, could be helpful in cases where patients wait until a relatively late stage of the disease to obtain medical treatment-;a frequent occurrence-;by which time the body’s own inflammatory responses to the infection are causing symptoms. “At that point, inhibition of virus replication might no longer be helpful, but honokiol’s anti-inflammatory response might mitigate the illness,” van Hemert explained.

Honokiol inhibits a later step of the viral replication cycle-;one that takes place after the virus has entered the cell. The investigators suspect that honokiol does so by triggering processes in the host cell that impede replication of the virus. It did so in the case of the original SARS-CoV-2 variants, and also in that of the more recent omicron variants.

At this early stage in the research, “Our study merely provides the basis for further research into potential therapeutic applications,” said van Hemert. “It is important to mention that it is too early to claim that honokiol might be used in SARS-CoV-2 patients. This requires much more research and-;if successful-;properly conducted clinical trials.”

Van Hemert learned about honokiol from Jack Arbiser, M.D., Ph.D., of Emory School of Medicine, during the early stages of the pandemic. Arbiser had been researching honokiol’s anticancer properties, and he told van Hemert he thought that the effects of the compound on the host cell might be beneficial for treatment of COVID-19 patients as well.

Clarisse Salgado-Benvindo, a Ph.D. student in van Hemert’s group, performed most of the experiments, using cultured cells that the researchers infected with SARS-CoV-2, or the highly pathogenic coronaviruses SARS-CoV and MERS-CoV. Experimenters worked inside a BSL-3 lab, which is a special high containment lab, while wearing protective suits with full-face masks to prevent infection.

Source:

American Society for Microbiology

Journal reference:

Salgado-Benvindo, C., et al. (2023) Honokiol Inhibits SARS-CoV-2 Replication in Cell Culture at a Post-Entry Step. Microbiology Spectrum. doi.org/10.1128/spectrum.03273-22.

Microbiology

Transforming antibiotic resistance testing: a novel, rapid and affordable technique

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Lily Ramsey, LLMInterview conducted by Lily Ramsey, LLMMay 19 2023
Thought LeadersDr. Sandor KasasResearch LeadEcole Polytechnique Fédérale de Lausanne

News Medical speaks with Dr. Sandor Kasas, a lead researcher at Ecole Polytechnique Fédérale de Lausanne in Switzerland. Here we discuss his recent development of a novel and highly efficient method for rapid antibiotic susceptibility testing using optical microscopy.

The new technique, known as Optical Nanomotion Detection (ONMD), is an extremely rapid, label-free, and single-cell sensitive method to test for antibiotic sensitivity. ONMD requires only a traditional optical microscope equipped with a camera or mobile phone. The simplicity and efficiency of the technique could prove to be a game changer in the field of antibiotic resistance.

Please can you introduce yourself, tell us about your career background, and what inspired your career in biology and medicine?

I graduated in medicine but never practiced in hospitals or medical centers. After my studies, I started working as an assistant in histology at the University of Fribourg in Switzerland. My first research projects included image processing, scanning tunneling, and atomic force microscopy.

Later, and for most of the rest of my scientific carrier, I focused primarily on the biological applications of AFM. For the past ten years, my research interest is about nanomotion, i.e., the study of oscillations at a nanometric scale of living organisms.

Image Credit: dominikazara/Shutterstock.comImage Credit: dominikazara/Shutterstock.com

You started working on biological applications of the atomic force microscope (AFM) in 1992. From your perspective, how has the antibiotic resistance landscape changed over the last two decades? What role has the advancement in technology played in furthering our understanding?

In the early ’90s, the AFM was mainly used for imaging. Later, AFM microscopists noticed that the instrument could also be used to explore the mechanical properties of living organisms. More recently, many “exotic” applications of the AFM have emerged, such as its use to weigh single cells or study their oscillations at the nanometric scale. In the 1990s, antibiotic resistance was not as serious a problem as today, but several teams were already using AFM to assess the effects of antibiotics on bacterial morphology.

The first investigations were limited to structural changes, but later, as the fields of application of AFM expanded, the instrument made it possible to monitor the mechanical properties of the bacterial cell wall upon exposure to antibiotics. In the 2010s, with G. Longo and G. Dietler, we demonstrated that AFM could also track nanoscale oscillations of living organisms. The very first application we had in mind was using the instrument to perform rapid antibiotic susceptibility testing.

We have therefore developed devices based on dedicated AFM technology to perform fast AST (i.e., in 2-4h). AFM-based nanomotion detection instruments are already implemented in medical centers in Switzerland, Spain, and Austria. However, this type of device has some drawbacks, including the need to fix the organism of interest on a cantilever. To overcome this limitation, we have developed with R. Willaert a nanomotion detector based on an optical microscope.

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Your most recent research has led to the development of a novel and highly efficient technique for rapid antibiotic susceptibility testing using optical microscopy. Please could you tell us why the development of rapid, affordable, and efficient testing methods is so important in the world of antimicrobial resistance?

Rapid antibiotic susceptibility testing could reduce the use of broad-spectrum antibiotics. Traditional ASTs based on replication rate require 24 hours (but up to 1 month in the case of tuberculosis) to identify the most effective antibiotic. Doctors prescribe broad-spectrum antibiotics between the patient’s admission to a medical center and the results of the AST.

These drugs quickly improve patients’ conditions but, unfortunately, promote resistance. A rapid AST that could identify the most suitable antibiotic within 2-4 hours would eliminate broad-spectrum antibiotics and increase treatment efficiency and reduce the development of resistant bacterial strains. Since bacterial resistance is a global problem, rapid ASTs should also be implemented in developing countries. Therefore, affordable and simple-to-use tests are needed.

Image Credit: Fahroni/Shutterstock.comImage Credit: Fahroni/Shutterstock.com

Were there any limitations and obstacles you faced in the research process? If so, how did you overcome them?

Antibiotic sensitivity detection with ONMD is very similar to the AFM-based technique. As long as the bacterium is alive, it oscillates; if the antibiotic is effective, it kills the micro-organism, and its oscillations stop. The first limitation we faced when developing the ONMD was our microscopes’ depth of field of view. To prevent the bacteria from leaving the focal plane of the optical microscope during the measurement, we had to constrain the microbes into microfluidic channels a few micrometers high.

Microfabrication of such devices is relatively straightforward in an academic environment, but we were looking for simpler solutions. One option for constructing such a device is to use 10-micron double-sided rubber tape. It allows you to “build” a microfluidic chamber in 5 minutes with two glass coverslips and a puncher.

Another challenge was nanoscale motion detection. For this purpose, we used freely available cross-correlation algorithms that achieve sub-pixel resolution. (i.e., a few nanometers). We first developed the ONMD for larger organisms, such as yeast cells, and expanded the method to bacteria. This further development took us around two years.

You worked alongside Dr. Ronnie Willaert, a professor of structural biology at Vrije Universiteit Brussel, on developing this new rapid AST technique. How did your areas of expertise and research backgrounds complement each other in developing ONMD?

R. Willaert is an expert in yeast microbiology and microfluidics, while our team in Lausanne is primarily involved in AFM-based nanomotion detection and applying AFM to clinically relevant problems. The two teams were supported by a joint grant from the Swiss National Science Foundation and the Research Foundation Flanders (FWO) which enabled the development of the method.

The field of antimicrobial resistance requires a high level of international collaboration, with everyone working together to achieve a common goal. With antimicrobial resistance rising to dangerously high levels in all parts of the world, how important is collaboration in this field?

Our project required expertise in various fields, such as microbiology, microscopy, microfluidics, programming, and data processing. In the development of rapid AST instruments and many others, only a multidisciplinary approach and close collaboration between teams with complementary expertise is today the only path to success.

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You and Dr. Willaert have said, ‘The simplicity and efficiency of the method make it a game-changer in the field of AST.’ Can you please expand on what makes ONMD a game changer in the AST field and what implications this research could have in clinical and research settings?

As mentioned earlier, bacterial resistance is a global health problem. Rapid AST should also be easily implemented in developing countries to limit the spread of resistant strains. The cheaper and simpler the technique, the more likely it is to be used on a large scale. We are convinced that the ONMD approach can meet these requirements. ONMD could also be used for drug discovery or basic research.

While we recognize the importance of rapid AST, what next steps must be taken before this technique can be used globally in research and clinical landscapes?

For fundamental research, there are no other important developments to be made. Any reasonably equipped research center can implement the technique and use it. Regarding implementing the technique in developing countries or extreme environments, stand-alone devices have to be used, which have yet to be manufactured.

There is a rapidly expanding need for efficient AST globally; however, the need for affordable, accessible, and simple techniques are of grave importance in developing countries disproportionately affected by antibiotic resistance due to existing global health disparities. Could this rapid AST technique be utilized in low-middle-income countries to slow the growing spread of multi-resistant bacteria? What would this mean for global health?

We are confident that ONMD-based AST testing can soon be implemented in research centers in both developed and developing countries. However, accreditation by the health authorities is necessary to use it as a standard diagnostic tool; this process can take several years, depending on the government health policy.

What’s next for you and your research? Are you involved in any exciting upcoming projects?

We want to develop a self-contained device for extreme environments. It would consist of a small microscope equipped with a camera and a data processing unit. The microfluidic part of the device could contain different antibiotics ready to be tested.

The ONMD technique could also monitor contamination levels in enclosed environments such as submarines, spacecraft, and space stations. One of our recent projects is funded by the European Space Agency (ESA) to develop a rapid antifungal susceptibility test that could work in microgravity. Additionally, ONMD could be used for even more exciting projects, such as chemistry-independent life detection in the search for extraterrestrial life.

Where can readers find more information?

  • Villalba MI, Rossetti E, Bonvallat A, Yvanoff C, Radonicic V, Willaert RG*, Kasas S.*.Simple optical nanomotion method for single-bacterium viability and antibiotic response testing. PNAS 2023, May 2;120(18):e2221284120. doi: 10.1073/pnas.2221284120. Epub 2023 Apr 24. PMID: 37094120. * Contributed equally. https://doi.org/10.1073/pnas.2221284120
  • Radonicic, V.; Yvanoff, C.; Villalba, M.I.; Devreese, B.; Kasas, S.; Willaert, R.G. Single-Cell Optical Nanomotion of Candida albicans in Microwells for Rapid Antifungal Susceptibility Testing. Fermentation 2023, 9:365. https://doi.org/10.3390/fermentation9040365
  • Parmar P, Villalba MI, Horii Huber AS, Kalauzi A, Bartolić D, Radotić K, Willaert RG, MacFabe DF and Kasas S. Mitochondrial nanomotion measured by optical microscopy. Front. Microbiol. 2023, 14:1133773. https://doi.org/10.3389/fmicb.2023.1133773
  • Starodubtseva MN, Irina A. Chelnokova IA, Shkliarava NM, Villalba MI, Tapalski DV, Kasas S, Willaert RG. Modulation of the nanoscale motion rate of Candida albicans by X-rays. Front. Microbiol. 2023, 14:1133027. https://doi.org/10.3389/fmicb.2023.1133027
  • Radonicic V, Yvanoff C, Villalba MI, Kasas S, Willaert RG. The Dynamics of Single-Cell Nanomotion Behaviour of Saccharomyces cerevisiae in a Microfluidic Chip for Rapid Antifungal Susceptibility Testing. Fermentation. 2022; 8(5):195. https://doi.org/10.3390/fermentation8050195

About Dr. Sandor Kasas

Nanomotion is a fascinating and novel approach to observing living organisms.

Our team focuses almost exclusively on recording the nanomotion of bacterial mitochondria and mammalian cells with optical and AFM-based devices.

Recently, we demonstrated that the technique could be used not only for fast antimicrobial sensitivity testing but also to explore the metabolism of unicellular organisms. We hope our efforts will permit us to expand the application domains of ONMD.

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Microbiology

Long-ignored antibiotic could help fight against multi-drug resistant bacteria

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Reviewed by Megan Craig, M.Sc.May 16 2023

“The end of modern medicine as we know it.” That’s how the then-director general of the World Health Organization characterized the creeping problem of antimicrobial resistance in 2012. Antimicrobial resistance is the tendency of bacteria, fungus and other disease-causing microbes to evolve strategies to evade the medications humans have discovered and developed to fight them. The evolution of these so-called “super bugs” is an inevitable natural phenomenon, accelerated by misuse of existing drugs and intensified by the lack of new ones in the development pipeline.

Without antibiotics to manage common bacterial infections, small injuries and minor infections become potentially fatal encounters. In 2019, more than 2.8 million antimicrobial-resistant infections occurred in the United States, and more than 35,000 people died as a result, according to the Centers for Disease Control and Prevention (CDC). In the same year, about 1.25 million people died globally. A report from the United Nations issued earlier this year warned that number could rise to ten million global deaths annually if nothing is done to combat antimicrobial resistance.

For nearly 25 years, James Kirby, MD, director of the Clinical Microbiology Laboratory at Beth Israel Deaconess Medical Center (BIDMC), has worked to advance the fight against infectious diseases by finding and developing new, potent antimicrobials, and by better understanding how disease-causing bacteria make us sick. In a recent paper published in PLOS Biology, Kirby and colleagues investigated a naturally occurring antimicrobial agent discovered more than 80 years ago.

Using leading-edge technology, Kirby’s team demonstrated that chemical variants of the antibiotic, called streptothricins, showed potency against several contemporary drug-resistant strains of bacteria. The researchers also revealed the unique mechanism by which streptothricin fights off bacterial infections. What’s more, they showed the antibiotic had a therapeutic effect in an animal model at non-toxic concentrations. Taken together, the findings suggest streptothricin deserves further pre-clinical exploration as a potential therapy for the treatment of multi-drug resistant bacteria.

We asked Dr. Kirby to tell us more about this long-ignored antibiotic and how it could help humans stave off the problems of antimicrobial resistance a little longer.

Q: Why is it important to look for new antimicrobials? Can’t we preserve the drugs we have through more judicious use of antibiotics?

Stewardship is extremely important, but once you’re infected with one of these drug-resistant organisms, you need the tools to address it.

Much of modern medicine is predicated on making patients temporarily — and sometimes for long periods of time — immunosuppressed. When these patients get colonized with these multidrug-resistant organisms, it’s very problematic. We need better antibiotics and more choices to address multidrug resistance.

We have to realize that this is a worldwide problem, and organisms know no borders. So, a management approach for using these therapies may work well in Boston but may not in other areas of the world where the resources aren’t available to do appropriate stewardship.

Q: Your team investigated an antimicrobial discovered more than 80 years ago. Why was so little still known about it?

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The first antibiotic, penicillin, was discovered in 1928 and mass produced for the market by the early 1940s. While a game-changing drug, it worked on only one of the two major classes of bacteria that infect people, what we call gram-positive bacteria. The gram-positive bacteria include staphylococcal infections and streptococcal infections which cause strep throat, skin infections and toxic shock. There still was not an antibiotic for the other half of bacteria that can cause human infections, known as gram-negative organisms.

In 1942, scientists discovered this antibiotic that they isolated from a soil bacterium called streptothricin, possibly addressing gram-negative organisms. A pharmaceutical company immediately licensed the rights to it, but the development program was dropped soon after when some patients developed renal or kidney toxicity. Part of the reason for not pursuing further research was that several additional antibiotics were identified soon thereafter which were also active against gram-negatives. So, streptothricin got shelved.

Q: What prompted you to look at streptothricin specifically now?

It was partly serendipity. My research laboratory is interested in finding new, or old and forgotten, solutions to treat highly drug-resistant gram-negative pathogens like E. coli or Klebsiella or Acinetobacter that we commonly see in hospitalized, immunocompromised patients. The problem is that they’re increasingly resistant to many if not all of the antibiotics that we have available.

Part of our research is to understand how these superbugs cause disease. To do that, we need a way to manipulate the genomes of these organisms. Commonly, the way that’s done is to create a change in the organism linked with the ability to resist a particular antibiotic that’s known as a selection agent. But for these super resistant gram-negative pathogens, there was really nothing we could use. These bugs were already resistant to everything.

We started searching around for drugs that we could use, and it turns out these super resistant bugs were highly susceptible to streptothricin, so we were able to use it as a selection agent to do these experiments.

As I read the literature on streptothricin and its history, I had the realization that it was not sufficiently explored. Here was this antibiotic with outstanding activity against gram-negative bacteria – and we confirmed that by testing it against a lot of different pathogens that we see in hospitals. That raised the question of whether we could get really good antibiotic activity at concentrations that are not going to cause damage to the animal or person in treatment.

Q: But it did cause kidney toxicity in people in 1942. What would be different now?

What scientists were isolating in 1942 was not as pure as what we are working with today. In fact, what was then called streptothricin is actually a mixture of several streptothricin variants. The natural mixture of different types of streptothricins is now referred to as nourseothricin.

In animal models, we tested whether we could kill the harmful microorganism without harming the host using a highly purified single streptothricin variant. We used a very famous strain of Klebsiella pneumoniae called the Nevada strain which was the first pan-drug-resistant, gram-negative organism isolated in the United States, an organism for which there was no treatment. A single dose cleared this organism from an infected animal model while avoiding any toxicity. It was really remarkable. We’re still in the very early stages of development, but I think we’ve validated that this is a compound that’s worth investing in further studies to find even better variants that eventually will meet the properties of a human therapeutic.

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Q. How does nourseothricin work to kill gram-negative bacteria?

That’s another really important part of our study. The mechanism hadn’t been figured out before and we showed that nourseothricin acts in a completely new way compared to any other type of antibiotic.

It works by inhibiting the ability of the organism to produce proteins in a very sneaky way. When a cell makes proteins, they make them off a blueprint or message that tells the cell what amino acids to link together to build the protein. Our studies help explain how this antibiotic confuses the machinery so that the message is read incorrectly, and it starts to put together gibberish. Essentially the cell gets poisoned because it’s producing all this junk.

In the absence of new classes of antibiotics, we’ve been good at taking existing drugs like penicillin for example and modifying them; we’ve been making variations on the same theme. The problem with that is that the resistance mechanisms against penicillin and other drugs already exist. There’s a huge environmental reservoir of resistance out there. Those existing mechanisms of resistance might not work perfectly well against your new variant of penicillin, but they will evolve very quickly to be able to conquer it.

So, there’s recognition that what we really want is new classes of antibiotics that act in a novel way. That’s why streptothricin’s action uncovered by our studies is so exciting. It works in a very unique way not seen with any other antibiotic, and that is very powerful because it means there’s not this huge environmental reservoir of potential resistance.

Q. You emphasize these are early steps in development. What are the next steps?

My lab is working very closely with colleagues at Northeastern University who figured out a way to synthesize streptothricin from scratch in a way that will allow us to cast many different variants. Then we can look for ones that have the ideal properties of high potency and reduced toxicity.

We are also continuing our collaboration with scientists at Case Western Reserve University Medical Center, diving more deeply to understand exactly how this antibiotic works. Then we can use that fundamental knowledge in our designs of future variants and be smarter about how we try to make the best antibiotic.

We have great collaborators that have allowed us to pursue a project that crosses multiple fields. This work is an example of collaborative science really at its best.

Co-authors included first author Christopher E. Morgan and Edward W. Yuof Case Western Reserve; Yoon-Suk Kang,Alex B. Green, Kenneth P. Smith, Lucius Chiaraviglio, Katherine A. Truelson, Katelyn E. Zulauf, Shade Rodriguez, and Anthony D. Kang of BIDMC; Matthew G. Dowgiallo,Brandon C. Miller, and Roman Manetsch of Northeastern University.

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Source:

Beth Israel Deaconess Medical Center

Microbiology

New compound with antibacterial activity shows promising results within one hour in laboratory trials

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Reviewed by Emily Henderson, B.Sc.May 15 2023

Resistance to antibiotics is a problem that alarms the medical and scientific community. Bacteria resistant to three different classes of antibiotics, known as multi-drug resistant (MDR) bacteria, are far from rare. Some are even resistant to all currently available treatments and are known as pan-drug resistant (PDR). They are associated with dangerous infections and listed by the World Health Organization (WHO) as priority pathogens for drug development with maximum urgency.

An article published in a special issue of the journal Antibiotics highlights a compound with antibacterial activity that presented promising results within one hour in laboratory trials.

The study was led by Ilana Camargo, last author of the article, and conducted during the doctoral research of first author Gabriela Righetto at the Molecular Epidemiology and Microbiology Laboratory (LEMiMo) of the University of São Paulo’s São Carlos Institute of Physics (IFSC-USP) in Brazil.

The compound we discovered is a new peptide, Pln149-PEP20, with a molecular framework designed to enhance its antimicrobial activity and with low toxicity. The results can be considered promising insofar as the trials involved pathogenic bacteria associated with MDR infections worldwide.”

Adriano Andricopulo, co-author of the article

Although novel antibacterial drugs are urgently needed, the pharmaceutical industry is notoriously uninterested in pursuing them, mainly because research in this field is time-consuming and costly, requiring very long lead times to bring viable active compounds to market.

The Center for Innovation in Biodiversity and Drug Discovery (CIBFar), a Research, Innovation and Dissemination Center (RIDC) set up and funded by FAPESP, looks for molecules that can be used to combat multidrug-resistant bacteria.

Camargo and Andricopulo are researchers at CIBFar, as are two other co-authors who study promising bactericidal compounds: Leila Beltramini and José Luiz Lopes.

For over a decade, the group formed by the collaboration between Beltramini and Lopes has analyzed Plantaricin 149 and its analogs. Plantaricins are substances produced by the bacterium Lactobacillus plantarum to combat other bacteria.

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Lactobacillus plantarum is commonly found in nature, especially in anaerobic plant matter, and in many fermented vegetable, meat and dairy products.

In the case of Plantaricin 149, Japanese researchers were the first to report its bactericidal action (in 1994) and since then scientists have been interested in obtaining more efficient synthetic analogs (molecules with small structural differences). In 2007, one of the first projects completed by the CIBFar team showed that the peptide inhibits pathogenic bacteria such as Listeria spp. and Staphylococcus spp. They then began studying synthetic analogs with stronger bactericidal activity than the original (causing more damage to the membrane of the combated microorganisms).

With the support of a scholarship from FAPESP, Righetto synthesized 20 analogs of Plantaricin 149, finding that Pln149-PEP20 had the best results so far and was also half the size of the original peptide. “The main advances in our research consist of the development of this smaller, more active and less toxic molecule, and the characterization of its action and propensity to develop resistance. It has proven to be highly promising in vitro – active against MDR bacteria and extensively resistant bacteria,” said Camargo, principal investigator for the project.

LEMiMo, the laboratory where the studies were conducted, has experience in characterizing bacterial isolates involved in outbreaks of hospital infections and holds a collection of bacteria selected for these trials in search of novel active compounds. The bacteria have the resistance profiles currently of greatest concern and were isolated during hospital outbreaks.

They are known in the scientific community by the term ESKAPE, an acronym for the scientific names of six highly virulent and antibiotic-resistant bacterial pathogens: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.

Further research can now be conducted to investigate the molecule’s action mechanism in more depth, to look for formulations, and possibly to develop an application. “In terms of the action mechanism, it’s also possible to use the cell morphology of the bacteria to identify cellular pathways affected by the peptide,” Righetto said. “As for optimization, the molecule can be functionalized by being linked to macrostructures, and the amino acid sequence can be modified.” Research is also needed on its cytotoxicity and on its selectivity (whether it affects healthy cells).

“We’re living in times of major global public health hazards due to a lack of antimicrobials that can be used to treat infections caused by extremely resistant bacteria. Antimicrobial peptides are targets of great interest for the development of novel candidate drugs. This novel molecule has the potential to be used as an innovative antimicrobial therapy, but further modifications and molecular optimizations still need to be investigated,” Andricopulo said.

Publication of the article also involved Harvard Medical School’s Infectious Disease Institute in Boston (USA) via researchers Paulo José Martins Bispo and Camille André.

Source:

São Paulo Research Foundation (FAPESP)

Journal reference:

Righetto, G. M., et al. (2023). Antimicrobial Activity of an Fmoc-Plantaricin 149 Derivative Peptide against Multidrug-Resistant Bacteria. doi.org/10.3390/antibiotics12020391.

Microbiology

Study identifies key genetic mechanism of drug resistance in the deadliest malaria parasites

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Reviewed by Emily Henderson, B.Sc.May 11 2023

An important genetic mechanism of drug resistance in one of the deadliest human malaria parasites has been identified in a new study published in Nature Microbiology.

A second key gene, pfaat1, responsible for encoding a protein that transports amino acids in the membrane of Plasmodium falciparum, is involved in its resistance to the major anti-malaria drug, chloroquine.

The findings may have implications for the ongoing battle against malaria, which infects an estimated 247 million people worldwide and kills more than 619,000 each year, most of which are young children.

Chloroquine is a major antimalaria drug, however in recent years, resistance has emerged in malaria parasites, first spreading through Southeast Asia and then through Africa in the 1970s and 1980s. Although alternative antimalarial drugs have been developed, resistance to chloroquine remains a big challenge.

Since its discovery in 2000, only one gene has been believed to have been responsible for resistance to chloroquine – the resistance transporter pfcrt which helps the malaria parasite transport the drug out of a key region in their cells, subsequently rendering it ineffective.

In this study, researchers from the Medical Research Council (MRC) Unit The Gambia at the London School of Hygiene & Tropical Medicine (LSHTM) analysed more than 600 genomes of P. falciparum that were collected in The Gambia over a period of 30 years. The team found that mutant variants of  a second gene, pfaat1, which encodes an amino acid transporter, increased in frequency from undetectable to very high levels between 1984 and 2014. Importantly, their genome-wide population analyses also indicated long term co-selection on this gene alongside the previously-known resistance gene pfcrt.

In the laboratory, a further team of researchers including from Texas Biomed, University of Notre Dame and Seattle Children’s Research Institute found that replacing these mutations in parasite genomes using CRISPR gene-editing technology impacted drug resistance. A team from Nottingham University also found that these mutations could impact the function of pfaat1 in yeast, resulting in drug resistance.

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Complementary analysis of malaria genome datasets additionally suggested that parasites from Africa and Asia may carry different mutations in pfaat1 which could help explain differences in the evolution of drug resistance across these continents.

Alfred Amambua-Ngwa, Professor of Genetic Epidemiology at MRC Unit The Gambia at LSHTM said: “This is a very clear example of natural selection in action – these mutations were preferred and passed on with extremely high frequency in a very short amount of time, suggesting they provide a significant survival advantage.

“The mutations in pfaat1 very closely mirror the increase of pfcrt mutations. This, and other genetic analyses in the paper demonstrate that the transporter AAT1 has a major role in chloroquine resistance.”

Grappling with drug resistance, for malaria and other pathogens, requires taking a holistic approach to both drug development and pathogen surveillance. We must be aware that different genes and molecules will be working together to survive treatments. That is why looking at whole genomes and whole populations is so critical.”

David Conway, Professor of Biology, LSHTM

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Source:

London School of Hygiene & Tropical Medicine (LSHTM)

Journal reference:

Amambua-Ngwa, A., et al. (2023). Chloroquine resistance evolution in Plasmodium falciparum is mediated by the putative amino acid transporter AAT1. Nature Microbiology. doi.org/10.1038/s41564-023-01377-z.

Microbiology

Anticoronavirals: the development of COVID-19 therapies and the challenges that remain

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Neha MathurBy Neha MathurMay 8 2023Reviewed by Danielle Ellis, B.Sc.

In a recent article published in Nature Microbiology, researchers highlighted the pace of development of coronavirus disease 2019 (COVID-19) therapies during the pandemic and the challenges that hinder the widespread availability of anticoronavirals.

Study: Therapeutics for COVID-19. Image Credit: Viacheslav Lopatin/Shutterstock.com
Study: Therapeutics for COVID-19. Image Credit: Viacheslav Lopatin/Shutterstock.com

Background

COVID-19 is the third coronavirus disease in the past 20 years after severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). While the two predecessors caused severe mortality, they did not cause a pandemic. On the contrary, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) triggered a pandemic, and by 21 February 2023, it had caused more than 757 million confirmed cases, including >6.8 million deaths worldwide.

Vaccines and monoclonal antibody (mAb) treatments for COVID-19 became available within a year of the pandemic. Yet, there is a substantial need for more effective therapeutics to treat unvaccinated and immunocompromised patients and those whose vaccine immunity waned over time.

About the study

In this study, the authors highlighted four stages of SARS-CoV-2 infection that require different therapeutic interventions as critical for identifying COVID-19 therapeutic targets. At stage 1, when viral replication begins inside the host, oral or intravenous administration of monoclonal antibodies and antiviral therapies are effective. However, an ideal time for prophylactic administration of vaccines is Stage 0 preceding the infection.

Clinical trials have established that mAbs and antivirals effectively combat COVID-19 when administered up to 10 days after symptom onset and within three to five days following the onset of symptoms, respectively. COVID-19 patients in stage 2 develop viral pneumonia, cough and fever, lung inflammation causing shortness of breath, and lung aberrations, such as ground glass opacities.

The most serious is stage 3 characterized by a hyperinflammatory state or acute respiratory distress syndrome (ARDS). Some patients might also develop coagulation disorders or shock or systemic inflammatory response syndrome (SIRS). Thus, at stage 3, a patient needs antiviral drugs and immunomodulatory therapy.

Stage 4 represents post-COVID-19 conditions when patients experience hyperinflammatory illnesses, e.g., multi-system inflammatory syndrome in children (MISC), following acute SARS-CoV-2 infection. Unfortunately, possible preventative measures and treatment for post-acute sequelae of SARS-CoV-2 (PASC) are not fully understood. It is a growing area of unmet medical need; thus, extensive research efforts are ongoing to classify PASC, which might be a conglomeration of several syndromes, and determine its cause(s).

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The National Institutes of Health (NIH) Treatment Guidelines Panel makes recommendations for the treatment and prevention of COVID-19. Early in the pandemic, clinicians used azithromycin and hydroxychloroquine as a possible COVID-19 treatment for hospitalized patients based on in vitro evidence of their synergistic effect on SARS-CoV-2 infection. Later, clinical trials found this combination ineffective. Similarly, the NIH panel did not specify recommendations for empirical antimicrobials.

The NIH rejected giving vitamin/mineral supplements, e.g., zinc, for hospitalized COVID-19 patients. On the contrary, they recommended prompt use of supplemental oxygenation and high-flow nasal cannula in patients with ARDS. In the absence of effective treatments, clinical recommendations by NIH continue to change and evolve.

Early drug repurposing efforts targeted nucleotide prodrugs, e.g., remdesivir (or GS-5734), AT-527, favipiravir, and molnupiravir (or MK-4482). However, only three antivirals received full Emergency Use Authorization (EUA) approval from the United States Food and Drug Administration (US-FDA), remdesivir, molnupiravir, and nirmatrelvir.

Pre-clinical characterization of remdesivir for other coronaviruses, pharmacokinetic and safety evaluation in humans in a failed clinical trial for Ebola virus, all acquired before the beginning of the COVID-19 pandemic, enabled rapid progression of remdesivir.

A phase 3 study conducted among patients in outpatient facilities and nursing facilities showed that remdesevir administration within seven days of symptom onset decreased hospitalization risk by 87%. Thus, its approval extended to high-risk non-hospitalized patients as well. Currently, phase 1b/2a study for inhaled remdesivir, and pre-clinical evaluation of an oral prodrug based on remdesivir is ongoing.

Another randomized phase III trial evaluated ivermectin, metformin, and fluvoxamine, all repurposed drug candidates, for early COVID-19 treatment of overweight or obese adults. Earlier pivotal efficacy and clinical studies found that molnupiravir provided no clinical benefit in hospitalized COVID-19 patients.

Conversely, the MOVe-OUT outpatient study demonstrated that treatment initiated within five days of symptom onset reduced the hospitalization risk or death. Accordingly, molnupiravir attained an EUA in the US on in late 2021 for treatment of mild-to-moderately ill COVID-19 patients at high risk of progression to severe disease. However, an outpatient study suggested that molnupiravir might augment SARS-CoV-2 evolution in immunocompromised individuals.

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In the USA, multiple initiatives have been undertaken to identify candidate agents that may be repurposed as COVID-19 drugs. For instance, the Bill and Melinda Gates Foundation launched the Therapeutics Accelerator in March 2020, wherein they adopted a three-way approach to test approved drugs, screen drug repositories, and evaluate novel small molecules, including mAbs against SARS-CoV-2.

Encouragingly, apilimod, a PIKfyve kinase inhibitor developed for treating autoimmune diseases, is being tested for COVID-19 in clinical studies. Likewise, multiple clinical trials are ongoing for camostat mesilate, an inhibitor of transmembrane protease serine 2 (TMPRSS2), an approved chronic pancreatitis treatment in Japan.

Among anti-inflammatory and immunomodulating drugs, dexamethasone, a corticosteroid, baricitinib, a Janus kinase (JAK) inhibitor, and tocilizumab have received FDA approval. Among mAb therapies, casirivimab with imdevimab and bamlanivimab with etesevimab, Sotrovimab, Bebtelovimab, Tixagevimab–cilgavimab have received FDA approval. However, as SARS-CoV-2 continues to evolve, changes in the spike protein led to EUAs being withdrawn for all mAb therapies due to loss of efficacy.

Conclusions

There is a vast knowledge gap regarding COVID-19 pathogenesis. Despite the absence of a viral reservoir, severe disease persists for weeks or even months after COVID-19 recovery. Another intriguing area of investigation is why autoantibodies increase over time during COVID-19. In February 2022, the government of the United States of America (USA) started a flagship program, RECOVER, to understand, prevent and treat COVID-19-related long-term health effects.

Amid decreasing vaccine uptake and waning efficacy of mAbs as SARS-CoV-2 mutates, there is a need for new, safe, and effective COVID-19 therapies for population-level deployment and the potential to reduce resistance development. Researchers need to accelerate research targeting small molecule candidates that would mechanistically target the conserved region of SARS-CoV-2 and not become ineffective across mutant strains.

To be prepared for another pandemic, a large repository of small molecules that have already progressed through early pre-clinical and clinical evaluation is needed to develop drugs, like remdesivir, developed in a short span of two years.

More importantly, research efforts should continue to advance the development of antivirals for other pathogens, including coronaviruses, in preparation for the next pandemic.

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Journal reference:
Microbiology

New Technology Could Make Missing Important Doses of Medicines and Vaccines a Thing of the Past

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The issue of missing essential doses of medicine and vaccines could become a thing of the past, thanks to new technology developed by bioengineers at Rice University. This state-of-the-art technology enables the production of time-release drugs.

“This is a huge problem in the treatment of chronic disease,” said Kevin McHugh, corresponding author of a study about the technology published online in Advanced Materials. “It’s estimated that 50% of people don’t take their medications correctly. With this, you’d give them one shot, and they’d be all set for the next couple of months.”

The consequences of not taking prescription medicine correctly can be devastating, resulting in a staggering annual cost. In the United States alone, it is estimated that the toll includes over 100,000 deaths, as much as 25% of hospitalizations, and a healthcare cost exceeding $100 billion.

Encapsulating medicine in microparticles that dissolve and release drugs over time isn’t a new idea. But McHugh and graduate student Tyler Graf used 21st-century methods to develop next-level encapsulation technology that is far more versatile than its forerunners.

Dubbed PULSED (short for Particles Uniformly Liquified and Sealed to Encapsulate Drugs), the technology employs high-resolution 3D printing and soft lithography to produce arrays of more than 300 nontoxic, biodegradable cylinders that are small enough to be injected with standard hypodermic needles.

The cylinders are made of a polymer called PLGA that’s widely used in clinical medical treatment. McHugh and Graf demonstrated four methods of loading the microcylinders with drugs and showed they could tweak the PLGA recipe to vary how quickly the particles dissolved and released the drugs — from as little as 10 days to almost five weeks. They also developed a fast and easy method for sealing the cylinders, a critical step to demonstrate the technology is both scalable and capable of addressing a major hurdle in time-release drug delivery.

“The thing we’re trying to overcome is ‘first-order release,’” McHugh said, referring to the uneven dosing that’s characteristic with current methods of drug encapsulation. “The common pattern is for a lot of the drug to be released early, on day one. And then on day 10, you might get 10 times less than you got on day one.

“If there’s a huge therapeutic window, then releasing 10 times less on day 10 might still be OK, but that’s rarely the case,” McHugh said. “Most of the time it’s really problematic, either because the day-one dose brings you close to toxicity or because getting 10 times less — or even four or five times less — at later time points isn’t enough to be effective.”

In many cases, it would be ideal for patients to have the same amount of a drug in their systems throughout treatment. McHugh said PULSED can be tailored for that kind of release profile, and it also could be used in other ways.

“Our motivation for this particular project actually came from the vaccine space,” he said. “In vaccination, you often need multiple doses spread out over the course of months. That’s really difficult to do in low- and middle-income countries because of health care accessibility issues. The idea was, ‘What if we made particles that exhibit pulsatile release?’ And we hypothesized that this core-shell structure — where you’d have the vaccine in a pocket inside a biodegradable polymer shell — could both produce that kind of all-or-nothing release event and provide a reliable way to set the delayed timing of the release.”

Though PULSED hasn’t yet been tested for months-long release delays, McHugh said previous studies from other labs have shown PLGA capsules can be formulated to release drugs as much as six months after injection.

In their study, Graf and McHugh showed they could make and load particles with diameters ranging from 400 microns to 100 microns. McHugh said this size enables particles to stay where they are injected until they dissolve, which could be useful for delivering large or continuous doses of one or more drugs at a specific location, like a cancerous tumor.

“For toxic cancer chemotherapies, you’d love to have the poison concentrated in the tumor and not in the rest of the body,” he said. “People have done that experimentally, injecting soluble drugs into tumors. But then the question is how long is it going to take for that to diffuse out.

“Our microparticles will stay where you put them,” McHugh said. “The idea is to make chemotherapy more effective and reduce its side effects by delivering a prolonged, concentrated dose of the drugs exactly where they’re needed.”

A video describing the research. Credit: Rice University

The crucial discovery of the contactless sealing method happened partly by chance. McHugh said previous studies had explored the use of PLGA microparticles for time-released drug encapsulation, but sealing large numbers of particles had proven so difficult that the cost of production was considered impractical for many applications.

While exploring alternative sealing methods, Graf noticed that trying to seal the microparticles by dipping them into different melted polymers was not giving the desired outcome. “Eventually, I questioned whether dipping the microparticles into a liquid polymer was even necessary,” said Graf, who proceeded to suspend the PLGA microparticles above a hot plate, enabling the top of the particles to melt and to self-seal while the bottom of the particles remained intact, “Those first particle batches barely sealed, but seeing the process was possible was very exciting.”Further optimization and experimentation resulted in consistent and robust sealing of the cylinders, which eventually proved to be one of the easier steps in making the time-released drug capsules. Each 22×14 array of cylinders was about the size of a postage stamp, and Graf made them atop glass microscope slides.

After loading an array with drugs, Graf said he would suspend it about a millimeter or so above the hot plate for a short time. “I’d just flip it over and rest it on two other glass slides, one on either end, and set a timer for however long it would take to seal. It just takes a few seconds.”

Reference: “A Scalable Platform for Fabricating Biodegradable Microparticles with Pulsatile Drug Release” by Tyler P. Graf, Sherry Yue Qiu, Dhruv Varshney, Mei-Li Laracuente, Erin M. Euliano, Pujita Munnangi, Brett H. Pogostin, Tsvetelina Baryakova, Arnav Garyali and Kevin J. McHugh, 2 March 2023, Advanced Materials.
DOI: 10.1002/adma.202300228

The study was funded by the Cancer Prevention and Research Institute of Texas, the National Institutes of Health, and the National Science Foundation.

Rice University

Microbiology

Saving Lives: Study Finds That Paxlovid Reduces Risk of COVID-19 Hospitalization and Death by 90%

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According to a study conducted by Kaiser Permanente, COVID-19 patients who receive prompt treatment with Paxlovid have a significantly reduced risk of hospitalization and death.

According to a study conducted by Kaiser Permanente and recently published in the journal The Lancet Infectious Diseases, Paxlovid, the combination of nirmatrelvir and ritonavir, has been found to be effective as an early-stage treatment in preventing hospitalization for people with mild to moderate COVID-19, irrespective of their age or prior immunity status.

“Among Kaiser Permanente members in Southern California who tested positive for coronavirus infection, receiving Paxlovid within 5 days of the start of COVID-19 symptoms was associated with substantial reductions in the risk of hospital admission or death,” said Sara Tartof, Ph.D., the senior author of the study and an epidemiologist with the Kaiser Permanente Southern California Department of Research & Evaluation. “These findings are even more notable because in this population with high levels of vaccination, we still see additional benefits of this treatment.”

Paxlovid is an oral therapeutic drug aimed at reducing the risk for severe outcomes of coronavirus infection. It is manufactured by Pfizer Inc. It currently has emergency use authorization by the U.S. Food and Drug Administration for adults and children 12 and older who are at high risk for progression to severe COVID-19.

The study analyses included patients with positive results from coronavirus tests undertaken in outpatient settings between April 8 and October 7, 2022. In the study population, 7,274 people had received Paxlovid, and 126,152 had not received Paxlovid. It was a time dominated by the omicron subvariants BA.2, BA.4, and BA.5. Overall, 86% of the 133,426 participants had received 2 COVID-19 vaccine doses, and 61% had received 3 or more.

The study found:

“Our data showed that the sooner people take Paxlovid upon symptom onset, the more effective the medication can be,” Tartof said. “However, there is still some benefit to treatment 6 or more days after symptom onset. People should talk with their doctors about the best approach for them.”

Reference: “Effectiveness of nirmatrelvir–ritonavir in preventing hospital admissions and deaths in people with COVID-19: a cohort study in a large US health-care system” by Joseph A Lewnard, John M McLaughlin, Debbie Malden, Vennis Hong, Laura Puzniak, Bradley K Ackerson, Bruno J Lewin, Jeniffer S Kim, Sally F Shaw, Harpreet Takhar, Luis Jodar and Sara Y Tartof, 15 March 2023, The Lancet Infectious Diseases.
DOI: 10.1016/S1473-3099(23)00118-4

Kaiser Permanente