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NOVA ScienceNOW

Killer Microbe: Expert Q&A

  • Posted 07.15.08
  • NOVA scienceNOW

On July 15, 2008, Michael Smith answered selected viewer questions about Iraqibacter (aka Acinetobacter baumannii), microbial resistance to antibiotics, and related issues. Please note we are no longer accepting questions, but see Arms Race With a Superbug (see Editors' Picks, left) for more information.

Michael Smith

Dr. Michael Smith graduated from the University of Wisconsin at Madison with a B.A. in Zoology. He earned his doctorate in the laboratory of Liza Pon at Columbia University studying organellar and cytoskeletal dynamics in yeast. Full Bio

Photo credit: Courtesy Michael Smith

Dr. Michael Smith graduated from the University of Wisconsin at Madison with a B.A. in Zoology. He earned his doctorate in the laboratory of Liza Pon at Columbia University studying organellar and cytoskeletal dynamics in yeast. In 2000, he joined Michael Snyder's lab at Yale University as an American Cancer Society Postdoctoral Fellow. His research focused on the genome sequencing and virulence strategies of the emerging human pathogen, Acinetobacter baumannii, known colloquially as Iraqibacter. Smith has been a member of the Research and Development team guiding Product Development of Human ProtoArrays at the Protein Array Center of the Invitrogen Corporation since 2006. Photo credit: Courtesy Michael Smith

Q: Is the Iraqibacter the same as Legionnaire's disease? Could it be carried on equipment that is shipped from one location to another, such as equipment for hospital use? It seems to me that this microbe could latch onto X-ray equipment, "transportable" beds, rooms, etc.

I'm an electrical technician and want to know more about the microbe that is spreading throughout the U.S. and how to combat it. Thanks. Jayme Chalogias, New Hampshire

Q: My husband served in Iraq. If he has been exposed to the bacteria, is he also colonized for life? Does this pose any threat to the health of my family? Anonymous

Michael Smith: Acinetobacter baumannii is a commonly found soil microbe. It is found here in the U.S. as well as in Iraq and other parts of the world, and I suspect that most people have been exposed to it during normal outdoor activities. Obviously, most people exposed to A. baumannii do not become sick or colonized. While this bacterium does have a knack for surviving for several weeks on dry surfaces, like the equipment you [Jayme] mention, A. baumannii is an opportunistic pathogen and only infects those with compromised immune systems, such as patients taking immunosuppressive therapies, those with immune disorders, and people who have endured enormous stress like our wounded warriors. Healthy individuals are unlikely to get sick with an A. baumannii infection.

A. baumannii is not the same as Legionella, the bacterium that causes Legionnaire's disease. Some antibiotic-resistant strains of A. baumannii contain genes that are also found in Legionella, but they are two distinct bacterial species.

Q: How is this bacteria acquired, and is it possible to spread this infection in this country? Anonymous

Q: Dr. Smith,

Where do these microbes reside, and how do they infect humans? Is there a way we can avoid getting infected? Thank you for your work. Franc Jaramillo, Hollywood, California

Q: As a truck driver, besides washing my hands, how can I prevent the spread of this to myself or others as I'm on the go and in public spaces on a regular basis? Should I carry a small bottle of bleach and water with me whereever I go and spray anything I touch that others touch? If so, what is the ratio of bleach to water? My husband caught non-drug-resistant staph in an airport, so ever since then I open doors with my arm or elbow and try hard not to touch anything in the public arena. How can we better protect ourselves and the public at large? Thanks. Mary, McKinney, Texas

Smith: As stated above, A. baumannii is a commonly found microbe, yet only infects those with compromised immune systems. Steps to reduce the possibility of infection are the same as for avoiding other germs. Repeated washing of one's hands is a great way to keep clean. The use of anti-microbial soaps is unnecessary; ordinary soap will clean hands and reduce the likelihood of infection dramatically. Do not wash your hands with bleach.

Q: Our area has a significant number of returning Iraqi war vets combined with a high senior census in our hospitals. What additional preventative measures are being recommended to keep these microbes from invading the patient population? Sharona Loewenstein, Spring Hill, Florida

Smith: There are several difficult-to-treat bacteria that are challenging hospitals and their staff worldwide. To reduce or eliminate the spread of bacterial infections from patient to patient, hospital staff will need to adopt improved sanitary practices. In England, for example, many doctors have stopped wearing lab coats and are now only wearing short sleeve shirts without neckties, to reduce the spread of methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile. These sorts of measures will also be effective at limiting the spread of A. baumannii infections.

Q: What is the current remedy for curring people with the Acinetobacter baumannii infection, and what is the mortality rate of that approach? Thanks. Michael Cabak, Aptos, California

Smith: Attributable mortality rates are difficult to determine with opportunisitic pathogens since the patients are typically sick prior to the onset of infection. In the event that a patient dies, was the infection to blame, was the prior condition to blame, or was it a combination of the two? Nonetheless, several publications have cited A. baumannii-attributable mortality rates at 8-30 percent. The current remedy is antibiotic therapy.

Q: Does bacterial resistance develop in the wild this way? For example, do plants make their own chemical defenses against diseases, to which bacteria evolve resistance? Or have we jumpstarted resistance with hospital treatment? Anonymous

Smith: Natural resistance to certain antibiotics can develop in the absence of the antibiotic itself. For example, polysaccharide capsules, cell walls, and other physical barriers that evolve for structural reasons may prevent certain drugs from reaching their site of action within the bacterial cell, and thus the microbe is resistant to particular antibiotics. However, much of the resistance that A. baumannii has acquired is specific to certain drugs (e.g., drug efflux pumps) and is propagated from generation to generation by selection due to constant exposure to the drug. Over time, the use (and overuse) of antibiotics, especially in hospitals, has encouraged the emergence of drug-resistant microbes. That is why many of the bacterial strains isolated from hospital settings are multidrug-resistant. We need to begin considering alternative measures to control bacterial populations without imposing such selections, so that when an antibiotic is necessary, it can be used effectively.

Q: How do you propose to end the overuse of antibiotics? This has been a major contribution to drug-resistant bacteria, and there needs to be a national, if not international, effort in this regard. Caryl McColly, Santa Cruz, California

Smith: I agree that it's necessary to put a stop to the misuse and overuse of antibiotics. It's important that the public be educated on the proper use of antibiotics and the consequences of unnecessary antibiotic prescribing. Although antibiotics are ineffective at treating viral infections such as the common cold, many patients with viruses still request antibiotics from their doctors!

In addition to educating the public, more research is needed to find alternative treatments for bacterial infections. In my opinion, the most intriguing area of research is in bacterial communication. Bacteria live as communities that communicate via chemical signals. Bacteria respond to these signals by initiating developmental pathways such as mating, cell motility, and virulence. If we target these communications systems, we can potentially turn off harmful virulence genes without the use of antibiotics.

Q: What benign bacteria did Iraqibacter evolve from, and what caused its transformation into a malignant disease? Anonymous

Smith: Mutations (or changes) in an organism's genomic DNA are the most common way that organisms acquire new abilities. These types of changes usually occur in increments and typically involve the loss, rather than gain, of functions. Microbes can also change more rapidly by acquiring DNA via horizontal gene transfer (HGT). HGT can happen a few different ways (e.g., mating or by infection with viruses or plasmids), but in the end, individual genes or collections of genes from a different source are introduced into an organism in a single step. These new genes can confer new abilities or functions to the organism, for example, the ability to grow in places it otherwise could not (e.g., in the presence of an antibiotic). The antibiotic-resistant strains of A. baumannii resulted from nonresistant strains that acquired resistance via HGT.

Q: Could the Iraqibacter be the result of a biological warfare experiment that "got loose", either during the first Gulf War, during the intervening Saddam years of the sanctions, or during the second Gulf War, when Bush invaded Iraq and there was extensive looting, with total chaos reigning?

Or, could it be something the Israelis accidentally let loose from their biological warfare experiments (which I know they must be doing)? Or could it be something that the U.S. covert biowarfare experimenters were using our troops as guinea pigs for and their experiment "got loose"?

Or, could it be something that got loose from Saddam's biological warfare experiments, probably aided by the U.S., when Bush, Cheney, and Rumsfeld were good buddies with Saddam? Are our troops unwitting guinea pigs, in other words? Linda Poole, Kevil, Kentucky

Q: Could this new Iraqi superbug be some sort of leftover biological weapon first devised by Saddam Hussein's scientists prior to the American invasion? Mark Piotrowski, Williamsburg, Virginia

Smith: Acinetobacter baumannii is found in soil all around the world. Drug-resistant strains have been documented and isolated everywhere from the United States to Korea. There is absolutely no reason to believe that multidrug-resistant A. baumannii is a genetically engineered biological weapon.

Q: I am an attorney. I represent the parents of a soldier [Sgt.] who was on his third tour of duty in Iraq. He became ill and was returned to the U.S., stationed at Ft. Benning. In almost exactly a month, he collapsed at his home. His wife called an ambulance and he was taken to a civilian hospital in Columbus, Georgia, where he died in less than an hour. The Armed Forces Institute diagnosed (I don't have my file and am paraphrasing from memory) bi-later hemorrhaging in both lungs as the cause of death. Does this sound like Iraqibacter? Any help would be appreciated. Thanks. Jim Hopewell, Riverdale, Maryland

Q: How does this bacteria present itself in soldiers in Iraq? My son has been home for two-plus years and has a "mass" in his lung and a "something" in his head as yet untested or identified. There has been speculation by the Army about cancer, fungus, bacteria infection, but nothing done. His other medical issues have been the focus of what little attention he has received: a leg injury, PTSD, TBI, Anxiety Disorder, etc. He was involved in a couple dozen IED attacks, some pretty serious. We are looking for help! Anonymous

Smith: It would be highly irresponsible for me to attempt a diagnosis of these soldiers. I would urge you both to consult the physicians who were (and are) treating these soldiers and ask them about the potential for A. baumannii infection playing a role in their sickness.

Q: What is the current thinking about treating resistant bacteria with phages? Has that concept been tested on Acetinobacter? Thanks. Anonymous

Smith: Phages are viruses that specifically infect and kill bacteria. Phage therapy has been used effectively to treat bacterial infections in many places around the world, including Russia. The key would be to identify an A. baumannii-specific phage, which I am unaware of. Secondly, bacteria are constantly evolving to evade phage infection. Thus, today's phage may not work tomorrow.

Q: Have you experimented with clay and the Iraqibacter? Certain clays have been found quite effective for a variety of microbes. Anonymous

Smith: Clay sounds like a novel and interesting method to control bacterial growth. However, I think that there are a number of questions that need to be resolved before it can be considered a bonafide therapy. How does it work and why don't all clays work? How can it be used to treat infections other than skin infections? In the end, I think that clay may have limited utility.

Q: According to [pyschic and author] Sylvia Browne's new book, there is going to be a bacteria that is like the flesh-eating microbe, and it will be found to be carried by birds. This is supposed to happen around 2009-2010. Can research be started now to study microbes that may come from this source? Amazing how such a tiny thing can kill so many large targets (us). I find it interesting that parasites kill off their hosts. What a world. Live, laugh, & love with what time we all may have left. Anonymous

Smith: You don't need to be a psychic to know that disease can spread from animals to humans. Animal (particularly avian) reservoirs of potential human pathogens are being actively researched. In many cases the pathogens are viral, such as SARS or influenza, but bacterial pathogens can also cross-infect, and thus measures to reduce that likelihood are also being taken.

Related Links

  • Killer Microbe

    A relatively benign bug becomes a highly lethal pathogen, known to U.S. soldiers as Iraqibacter.

  • Arms Race With a Superbug

    Certain microbes evolve defenses against every antibiotic we throw at them. Staph aureus is a sobering case in point.

  • Putting Bacteria to Work

    Bacteria help us in all kinds of ways, from fermenting foods to aiding medicine, cleaning oil spills to mining minerals.

  • Evolution in Action

    In this game, change the environment of "living" things and see how random mutations help them survive.