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Microbial Drug Resistance Virulence (MDRV)
08.07.09

Overview | Description | Applications | Operations | Results | Publications | Images

Experiment/Payload Overview

Brief Summary

Microbial Drug Resistance and Virulence (MDRV) will evaluate microbial drug resistance and the mechanisms of virulence (infection potential) in microbial cultures.

Principal Investigator

  • David Niesel, Ph.D., University of Texas Medical Branch, Galveston, TX
  • Michael McGinnis, Ph.D., University of Texas Medical Branch, Galveston, TX
  • Barry Pyle, Ph.D., Montana State University, Bozeman, MT
  • Cheryl Nickerson Ph.D., Arizona State University, Tempe, AZ

    • Co-Investigator(s)/Collaborator(s)

    Information Pending

    Payload Developer

    BioServe Space Technologies, University of Colorado, Boulder, CO

    Sponsoring Agency

    National Aeronautics and Space Administration (NASA)

    Expeditions Assigned

    |16|

    Previous ISS Missions

    A precursor to this investigation, Bacter was performed on STS-107; The specimens from STS-107 were not returned due to the Columbia accident in February 2003. Similar investigations, Microbe was performed on STS-115/12A and SPEGIS was performed on STS-118/13A.1

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    Experiment/Payload Description

    Research Summary

    • Previous space flight studies have demonstrated changes in bacterial and fungal growth rates, virulence (infection potential), host susceptibility (vulnerability) to infection and changes in drug resistance. However, these changes are not yet fully understood. Because of past findings it is hypothesized that during long-duration space flight, the virulence of pathogenic (disease producing) microbes may be enhanced and normally harmless microbes might become pathogenic.


    • In addition, past research suggests that infections with these microbes may be more difficult to treat using conventional antibiotic or antifungal drugs. Assessing the ability of space flight to elicit alterations in virulence parameters is essential in determining microbial risks and identifying options for reducing those risks to crewmembers during long-duration International Space Station (ISS), Lunar, and Martian missions.


    • Microbial Drug Resistance Virulence (MDRV) supports four independent investigators to determine the effect of space flight on the gene expression and virulence potential of four model microorganisms, Salmonella typhimurium, Streptococcus pneumoniae,Saccharomyces cerevisiae and Pseudomonas aeruginosa. These microorganisms were chosen because they are well studied organisms that have been, or have the potential to be, isolated from the Space Shuttle, Mir Space Station, International Space Station, or its crew, or have been shown to exhibit altered virulence in response to space flight. These organisms are all important human pathogens that cause a significant amount of human morbidity and mortality on Earth as well.

    Description

    Human presence in space, whether permanent or transient, will be accompanied by the presence of microbes. Numerous studies have suggested that space flight results in a suppression of the immune system in both humans and animals. Studies have seen a relative increase in the number and distribution of potentially disease causing microbes. Additionally, recent work from the Effect of Spaceflight on Microbial Gene Expression and Virulence (Microbe) experiment flown on Shuttle mission STS-115/12A in September 2006 showed that space flight increased the virulence of Salmonella typhimurium in a mouse model of oral infection. Furthermore, ground-based microbial studies, conducted in a rotating wall vessel bioreactor, an instrument that provides an environment that simulates some aspects of space flight (Modeled Microgravity), have demonstrated changes in bacterial virulence (ability to cause disease), stress resistance, and gene expression. While the changes that occur to microorganisms during space flight are not fully understood, changes have now been documented in bacterial and fungal growth rates, virulence, drug resistance and gene expression.

    During long-duration space flight, the virulence of pathogenic microbes may be enhanced and normally harmless or opportunistic microbes may become pathogenic. In addition, infections with these microbes may be more difficult to treat using conventional antibiotic or antifungal drugs. Taken together, these findings suggest an increased risk of infectious disease occurring during space flight. These possible microbial adaptations to space flight could be intensified, as humans inhabit the space environment for longer durations while undergoing reduced immune system function and using regenerative life support systems. Therefore, assessing the ability of space flight to elicit alterations in virulence parameters is essential in determining microbial risks and identifying options for reducing those risks to crewmembers during long-duration International Space Station (ISS), Lunar, and Martian missions.

    Four independent investigators will utilize the Microbial Drug Resistance Virulence (MDRV) space flight research opportunity on board STS-123/1J/A, to replicate previous results from earlier studies. Previous results have determined space flight does impact the gene expression and virulence potential of certain microorganisms. For this current study, Salmonella typhimurium, Streptococcus pneumoniae, Saccharomyces cerevisiae and Pseudomonas aeruginosa will be investigated because they are well studied organisms, have been examined during space flight and have been, or have the potential to be, isolated from the Space Shuttle, Mir Space Station, International Space Station or its crew.

    Two organisms will be specifically evaluated for their virulence potential, S. typhimurium and S. pneumoniae. S. typhimurium was chosen for two important reasons:

    • It is a common pathogen that was found to have global changes in gene expression and increased virulence when grown in modeled microgravity and space flight conditions.

    • It is a leading reason for disqualification of foods destined for the International Space Station (ISS).
    S. typhimurium will be grown under three different conditions, rich media, minimal media and rich media supplemented with custom salts. This will allow for the comparison between space flight-induced alterations in S. typhimurium virulence in nutrient-rich media as compared to growth in nutrient-limited media, as it is well known that the physiology and virulence potential of microorganisms can change in response to alterations in nutritional status. This research will not only serve to reproduce the results from the Effect of Spaceflight on Microbial Gene Expression and Virulence (Microbe) investigation based on S. typhimurium cultures grown on the STS-115/12A Space Shuttle mission, but will also allow for testing a new hypothesis, specifically that the modulation of different ion concentrations may be used to counteract or inhibit the space flight and space flight analogue-associated pathogenic responses in microorganisms, using Salmonella as the model organism. S. pneumoniae was chosen because it is a gram positive opportunistic pathogen capable of causing disease in people with compromised immune systems; this pathogen was flown previously on STS-118/13A.1 in the Streptococcus pneumoniae Expression of Gene in Space (SPEGIS) investigation. The recovered cultures were studied for alterations in gene and protein expression and alterations in virulence properties. MDRV will permit a reflight of this opportunistic pathogen, S. pneumoniae, so that virulence can specifically be evaluated to complement the previous findings.

    The second part of this experiment will study the effects of space flight on gene expression of specific virulence factors for S. typhimurium, S. pneumoniae and P. aeruginosa. These organisms will be grown under very similar conditions on the same mission using the same hardware. This will permit the side-by-side comparison of the effect of space flight on bacterial gene expression, including those genes important for pathogenicity.

    A third part of the study will evaluate resistance of S. cerevisiae (yeast) to the antifungal agent, voriconazole. Yeast will be grown in space under various concentrations of the antifungal compound to determine if these cells can grow in normally inhibitory concentrations of the antifungal drug.

    The investigators believe that information gained from these studies will prove beneficial in assessing microbiological risks and options for reducing those risks during space missions. When taken together, these studies will ultimately provide significant insights into the molecular basis of microbial virulence. Once specific molecular targets are identified, there is the potential for vaccine development and other novel strategies for prevention and treatment of disease caused by these microbes both on the ground and during space flight.

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    Applications

    Space Applications

    Results from these experiments could provide important information on the threat of pathogens in the space environment. This could assist with development of diagnostic tools to monitor the atmosphere, water and surfaces for the presence of these microbes as well as developing countermeasures to manage infections. Understanding the molecular responses of these organisms to space flight is a necessary step that will significantly contribute improved systems for keeping crewmembers safe. Furthermore, identification of the changes caused by space flight to gene expression and proteins could provide novel targets for pharmacological intervention to prevent and control infectious disease, which will ultimately facilitate safe and productive long-term exploration of the Moon and Mars.

    Earth Applications

    By understanding the unique spectrum of microbial genetic and virulence changes induced by space flight, this experiment could yield valuable knowledge leading to advances in vaccine development and other therapeutics for treatment, prevention and control of infectious diseases on Earth as well as in space.

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    Operations

    Operational Requirements

    The microbes will be contained in the glass barrel of a Fluid Processing Apparatus (FPA). The FPA is a tube that contains 2 or 3 separate liquids in addition to the sample. The liquid can be introduced to the sample in a controlled order. The FPA is contained in a Group Activation Pack (GAP). The GAP will hold up to 8 FPAs that can be processed simultaneously. For activation and termination, the crew will turn a hand crank that has been inserted onto the top of the GAP. Growth of the samples will last for a predetermined period of time before the experiment is terminated. Once the samples are on the ground and have been stabilized, a portion of the samples will be frozen at minus 80 degrees C then shipped to the investigator laboratories. The remaining samples will be used in the virulence studies to be examined for virulence potential immediately upon return to Earth This payload will be conducted under ambient temperature condition and will not require image or data download.

    Operational Protocols

    The different microbes will be contained in a Fluid Processing Apparatus (FPA). In order to activate the samples, the crew will turn a hand crank that has been inserted onto the top of the GAP which contains the FPAs. This will release the growth media into the samples initiating growth. The samples will grow for a predetermined period of time in ambient conditions. The crew will then turn the hand crank again to introduce another media to terminate the growth. Once the samples have returned to ground, the live cells will be used in virulence studies while the stabilized samples will be either refrigerated or frozen to minus 80 degrees C and shipped to the investigator laboratories for gene expression studies.

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    Results/More Information

    Human presence in space will be accompanied by the presence of microbes. Numerous studies have suggested that space flight results in a suppression of the immune system in both humans and animals. Additionally, recent work from the Effect of Spaceflight on Microbial Gene Expression and Virulence (Microbe) experiment flown on Shuttle mission STS-115/12A in September 2006 showed that space flight increased the virulence of Salmonella typhimurium. While the changes that occur to microorganisms during space flight are not fully understood, changes have now been documented in microbial growth rates, virulence, drug resistance and gene expression.

    During long-duration space flight, the virulence of pathogenic microbes may be enhanced; allowing normally harmless or opportunistic microbes to become pathogenic. In addition, infections with these microbes may be more difficult to treat using conventional drugs. Taken together, these findings suggest an increased risk of infectious disease occurring during space flight. These possible microbial adaptations to space flight could be intensified, as humans inhabit the space environment for longer durations. Therefore, assessing the ability of space flight to elicit alterations in virulence parameters is essential in determining microbial risks and identifying options for reducing those risks to crewmembers during long-duration International Space Station (ISS), Lunar, and Martian missions.

    With this in mind the Microbial Drug Resistance and Virulence (MDRV) experiment was performed in March 2008 during the STS-123/1JA mission to the ISS; it tested four microbial pathogens, Salmonella typhimurium, Streptococcus pneumoniae, Saccharomyces cerevisiae and Pseudomonas aeruginosa. Initial MDRV results focus on S. typhimurium grown in three different conditions, rich media, minimal media and rich media supplemented with custom salts. A recently published paper, Wilson et.al. 2008, indicates that space flight S. typhimurium cultures exhibited increased virulence when grown in rich media as compared to cultures grown in minimal media, rich media supplemented with custom salts and ground controls.

    Rich media supplemented with custom salts was sufficient to prevent increased virulence seen in the S. typhimurium grown in rich media during space flight. Subsequent ground based testing indicated an altered acid tolerance was prevented in S. typhimurium grown in rich media supplemented with custom salts. These results show a correlation between phosphate ion concentration and the changes to S. typhimurium to space flight.

    The results of these studies exhibit a model in which altering ion concentration controls the space flight associated virulence of microorganisms. Applications of these studies hold great promise for reducing risk to crew health during space flight and can be exploited to develop new strategies to combat infectious disease on Earth.

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    Related Web Sites
  • The Biodesign Institute Arizona State University
  • NASA Press Release: Space Research May Help Explain Salmonella Illness

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    Publications

    Results Publications

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      Related Publications

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      Images

      imageNASA image: S123E009086 Dominic Gorie, STS-123 commander, watches Group Activation Pack (GAP) float, containing Microbial Drug Resistance Virulence (MDRV). Photo was taken during STS-123 / Expedition 16 joint operations.
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      imageCo-Principal Investigator Cheryl Nickerson, Ph.D. Image courtesy of the Biodesign Institute, Arizona State University.
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      Information Provided and Updated by the ISS Program Scientist's Office
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