Civil War ghost soldiers

Top: P. luminescens infected waxworms
Bottom: nematodes with glowing bacteria
Image via microbewiki.kenyon.edu

An interesting story via io9.com, which presents a neat example of mutualism, microbial antagonism, and the effects of temperature on growth rates. It’s actually a story that’s been around for about 10 years, but recently showed up in the news.  Two high school students, Bill Martin and Jon Curtis from Bowie, MD won the Intel International Science Fair competition in 2001 with their research into the curious story of soldiers who survived being wounded at the Battle of Shiloh during the Civil War in the spring of 1862.

Bill and Jon were interested in an anecdote about how some of the wounded soldiers who had to remain at the battleground in the rain and mud for up to two days before medics could reach them noticed that their wounds were glowing in the dark. Furthermore, these soldiers appeared to have a better survival rate than other soldiers, and their wounds healed more quickly. The glowing wounds were nicknamed the “Angel’s Glow,” and nothing more was known about them for over 140 years. The two high school students deduced that the glow might be due to the action of a bioluminescent bacterium called Photorhabdus luminescens, which shares an interesting life cycle with a soil dwelling roundworm called a nematode.

P. luminescens lives in the digestive tract of the worm as part of the worm’s normal microbial flora. The nematodes in turn hunt for insect larvae in the soil. When a nematode burrows into an insect, it regurgitates the bacteria, which then begin to kill the insect and inhibit the growth of other bacteria in a demonstration of microbial antagonism. The nematode and the bacteria digest the inside of the insect until it is completely hollowed out. The nematode then re-ingests the bacteria and moves onto another insect to repeat the process. The nematode and the bacterium therefore share a mutualistic relationship with one another, as the bacterium benefits from being transported from food site to food site (the hapless insect larvae), and the worm benefits as the bacterium help to break down the insect into a usable source of food.

Ordinarily, P. luminescens is not a significant pathogen of humans, as its maximal tolerated growth temperature is below human body temperature. However, as the soldiers waited for medics to arrive at the battlefield, they became hypothermic in the early spring nights. This allowed their wounds to become infected by the nematodes and the bacteria, and the growth of these bacteria in turn inhibited the growth of other pathogens. When the wounded soldiers were removed from the field and warmed up, their temperature was then too high to permit growth of P. luminescens. Because P. luminescens  grew in the wounds for several days, the growth of wound-infecting pathogenic bacteria such as Staphylococcus and Streptococcus was limited. In soldiers who did not have the glowing wounds, growth of pathogens prior to treatment led to their much lower survival rates.

So would deliberate infection with Photorhabdus  be a reasonable approach to antisepsis? Here is a BONUS opportunity: in the comment thread, suggest a reason why this might not be a tenable proposal for therapy over at York Hospital.

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About ycpmicro

My name is David Singleton, and I am an Associate Professor of Microbiology at York College of Pennsylvania. My main course is BIO230, a course taken by allied-health students at YCP. Views on this site are my own.

Posted on April 11, 2012, in A bit 'o history, Bonus!, Strange but True and tagged , , , . Bookmark the permalink. 13 Comments.

  1. Colleen Justison

    This might not be a good therapy because changing the temperature of a patient to a lower one can be life threatening even if it does help with antisepsis. Hypothermia can cause problems with your kidney, liver, and heart.

  2. A reason why this might not be a tenable proposal for therapy over at York Hospital is because yes lowering the body temperature will prevent other pathogens to grow in the body, and will help P. luminescens be inhabitable in the human body; but lowering the body temperature of humans is not good for metabolism. Yes it will help to prevent pathogens but will increase the person’s chances of causes other organs to not work causing the person to be even sickier than they were to start with.

    • So what are the time frames for therapeutic hypothermia (indicated in the link I gave above in response to Colleen) in comparison to the time frames from this non-medically indicated use?

  3. Since P. luminescens acts by microbial antagonism, could the bacterium also kill normal flora? By infecting a patient with this bacteria, you take the risk of killing beneficial bacteria who under normal temperatures work to stimulate a normal immune system with beneficial microbial antagonism.

    • An interesting point, but I think that it was a non-issue with the wound infections in the story. In that situation (open wounds) there is not a normal microbial flora that would be subject to antagonism; just pathogens that we don’t want to grow anyway. Certainly, infection of a body site with a normal flora would present a problem.

  4. I agree that hypothermia is a factor that can be dangerous to the patient, but it is a procedure that can be done as long as it is done correctly especially during the rewarming process. I view deliberately infecting a patient with bacteria as a legal issue for York Hospital. It can be seen as unethical to subject the patient to a procedure that can lead to death with malpractice suits against the hospital and against personnel performing the procedure. There are modern and less life threatening antiseptic techniques that the hospital can implement without loss of life, money and reputation.

    • I did relate the story earlier in the term about deliberately infecting a patient with intestinal parasites, in order to abrogate the signs and symptoms of Crohn’s Disease. That situation, as well as this one, took advantage of an introduced organism (a roundworm, or a bacterium) that is poorly adapted to life on the human body. So these alternative therapeutic approaches have benefits, and with the rapid increases in antibiotic resistance that we are currently seeing in hospital settings, sometimes “thinking outside the box” is necessary!

  5. I believe the main concern with this idea is ethical–deliberatly infecting a patient with a bacteria or virus is in violation of medical ethics. Koch’s Postulate has yet to be tested on HIV/AIDS due to this very concern. Subjecting the patient to hypothermic conditions is also a viable concern but this treatment CAN be done and it can be done SAFELY. I’m not sure if there is a safe way to inject a human with a virus or bacterium. There are several medical situations which hypothermia can help to control including hypoxia-ischemia in newborn patients as well as neurogenic fever. But there are also several problems with it, to include risk of damage to internal organs and the ability of the low temp. to inhibit bacterial metabolism. The durastic temperature change in the body could inhibit the growth of “good” bacteria and at the same time provide favorable conditions that allow P. luminescens to thrive and survive. However, if the patient is monitored closely and the surrounding medical staff are aware of the potential problems that could arise, the patient’s well being will most likely not be compromised. Therefore, I believe the biggest concern with using this proposed treatment plan rests with the ethic violation in which it presents. A hospital is not going to be willing to put a patient’s health or wellbeing in jeopardy if there are other, less expensive treatment plans that can be initiated to deal with the condition.

    • I disagree with the premise that this represents a violation of medical ethics. Most modern medical procedures do accomplish an incredible amount of damage to the body; just consider the process of open heart surgery, where we split open a patient’s chest, deliberately stop their heart, and in many cases purposefully lower their body temperature. Consider the case of radiation therapy, where we blast the body with levels of ionizing radiation that causes a multitude of ancillary effects on the body.

      With infections, I cited the above example that we had in class about deliberate infection with porcine roundworms to accomplish therapy, and many hospitals are going back to the medicinal use of leeches.

      Physicians already violate the Oath of Hippocrates to “Do No Harm” every time they lance a boil, but this is only in violation of medical ethics if the method is not warranted by the outcome. In the Civil War story above, I would posit that the outcome (patients survived for several days in the field, and did not develop septicemia) was superior to the alternative, which was death.

      Deliberate infection of patients can and does occur, particularly with medical research to identify therapies superior to the ones currently used. Consider the case of the Yellow Fever Commission, led by Walter Reed, which identified the etiologic agent of that disease. Human trials in infectious disease has and must occur, however guidelines for informed consent (as occurred during the hunt for Yellow Fever) must be followed. What we want to avoid as health care scientists are situations like the reprehensible Tuskeegee Syphilis Study, or this even worse avenue of experimentation.

      • I agree that on order to progress in medicine, deliberate infection must occur as long as informed consent is followed properly. But with your example about the open heart surgery, usually an open heart surgery is the last resort if there are absolutely no other options and going without the open heart procedure would cause death . The same can be said for radiation. Many cancer patients opt not to have radiation done unless its the last resort and many other treatments have failed. It may be that we are putting these patients in harms way but both the heart surgery and radiation are not the first lines of defense-other therapy is used first and fails before the invasive treatments are initiated. So my question is would you still not consider it an ethical violation to deliberately infect a patient with a bacteria/virus as a first treatment plan when there are other methods that have not been tried yet that don’t involve deliberate infection? Also, if deliberate infection were not an ethical issue then why hasn’t Koch’s Postulate been tried on HIV/AIDS? When we look at medical ethics in regards to deliberate infection and advancement of medicine, how do we discern which diseases are ok to infect a patient with and which are not? All bacterium and viruses carry with it at least a potential for death bc we can never be certain how a patients body will react to the infection. So you advocate for deliberate infection for the advancement of medicine in this case, but what if the pathogen in question were HIV? Would that turn it into a violation of ethics bc of HIV’s virulence?

        • Presumably as medical research identifies novel therapies, open heart surgery could become obsolete. We may have to wait for Star Trek for that. However, without research using ethical guidelines, we will never get to the 23rd century.

          We deliberately infect people with organisms on a daily basis, when we use an attenuated vaccine, in the treatment for Crohn’s Disease I mentioned in class, and every time you eat yogurt with probiotics. See this blog posting for a novel way to treat cancer using Clostridium novyi, a bacterium very closely related to the one that causes tetanus and botulism, or by treating cancer with vesicular stomatis virus. In both of these situations, deliberate infection is being proposed, and holds incredible promise for treatment of disease.

          And ALL organisms (even attenuated pathogens) carry with them the potential for disease. It is again a matter of ascertaining the risk due to that infection, and whether the benefits will outweigh the risks. In the case of vaccines, the answer is clearly “yes.” In the case of Photorhabdus, I would argue that the answer is again possibly yes, as the pathogenic potential of that organism in not great under normal circumstances, and if the alternative is death due to sepsis in the face of antibiotic resistant Staphylococcus, I would argue that could potentially be a situation of “last resort.”

  6. The clue that I was dangling above for Kaela’s comment about “time frames” was this: the amount of time necessary to achieve benefit from infection by Photorhabdus is likely longer than the window where induced hypothermia might be achieved safely.

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