Another source for antibiotic resistant microbes

Carlsbad Caverns, image via National Park Service

Here at BIO230, I’ve put up news articles relating the medical certainty of antibiotic resistance in bacteria. Diseases that were easily resolved less than a generation ago are now becoming increasingly difficult for health care workers to treat, and consequently prevention (particularly in health care settings) has become a more and more critical endeavor. Furthermore, the genetic elements for resistance to many common antibiotics appear to be present in bacteria, before they ever come into contact with these antibiotics, as detailed from this report examining 30,000 year old bacteria isolated from Siberian permafrost. A new report in the medical journal PLoSONE, and summarized at pushes back this boundary even further.

Researchers at McMaster University in Ontario, and the University of Akron examined the microbiome of an isolated section of Leguchilla Cave in New Mexico. The section of the cave that was examined have been geologically and environmentally isolated for 4 million years, with extremely minimal human incursion into these regions. Cave samples were prepared for plating in situ, spread onto a variety of culture media designed to mimic the cave environment, and then incubated in the dark for 2 to 6 weeks at 21°C, which is the temperature of Leguchilla Cave. Isolated colonies were then subcultured on rich media for subsequent analysis. 

Figure 2 from Bhullar et al

A screen of antibiotic resistance of these microorganisms is shown in the figure to the left. Significant percentages of the culturable organisms demonstrate resistance at clinical levels to many common antibiotics, with resistance to folate pathway and cell wall synthesis inhibiting antibiotics being very common. This reservoir of antibiotic resistance points to a mechanism for acquisition of resistance in clinically relevant species; they are able to acquire resistance in many cases through genetic exchange with environmental species, which helps to explain the rapidity of resistance emergence in many cases. The authors state:

This work demonstrates that antibiotic resistance is widespread in the environment even in the absence of anthropogenic antibiotic use. Lechuguilla Cave represents a remarkable ecosystem that has been isolated for millions of years, well before the clinical and agricultural use of antibiotics. The presence of multidrug resistant organisms even in this pristine environment reinforces the notion that the antibiotic resistome is an ancient and pervasive component of the microbial pangenome.

All is not gloomy, as several bright points can be brought forward with this report. First, none of the isolated organisms from Leguchilla Cave represent even remotely pathogenic microorganisms, so the health risk directly due to these organisms is negligible. Second, genes found in these microorganisms that can confer antibiotic resistance might be used as molecular “tags” that health care workers might watch for in the emergence of antibiotic resistance in clinical settings. Third, the widespread presence of antibiotic resistance to known antibiotics in a presumably pristine environment infers the existence infers the existence of novel antibiotics in the environment that might, for at least a period of time, help us to remain temporarily ahead of the curve in treating infectious disease.


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 20, 2012, in Danger danger danger!, Strange but True and tagged , , , . Bookmark the permalink. 9 Comments.

  1. I think this is fascinating, because if we can find trends of what natural, untainted bacteria are inherently resistant too and graph these findings. And using these findings along with knowing where infectious organisms occur in nature we can begin to compile better ways to treat infections!

    • What I think that these studies are pointing out is that the microbes are all ahead of us, with respect to deploying resistance mechanisms to antibiotics, and in fact there may very few if any compounds that a given bacterium could potentially develop resistance to.

      Our best recourse in this case is to continue to work to prevent overuse, which will promote the emergence of antibiotic resistance. It also underscores the fact that antibiotic resistance is not a matter of “if it will happen,” but instead is “when it will happen.”

      • I absolutely agree, especially in this day and age where people are so quick to go to the doctor for just the sniffles, and some doctors tend to distribute medications like candy. I do think its interesting also that simple bacteria and even simpler still viruses can change and mutate to adapt to their changing environment.

  2. You say that this helps us “remain temporarily ahead of the curve in treating infectious disease.” That’s a scary statement because of the truth behind it. I agree with Lynn because ppl are extremely quick to go to the doctor and be treated for the smallest ailments, at which time the docs RX medicines like there’s no tomorrow. Your suggestion of the best recourse of action is to prevent overuse of these medicines but is there really any way to do that in this country? Millions of doctors arent aware of this topic or they are aware and dont care either because they get some type of kick back from the pharmaceutical companies based on how many scripts they write, or because they just dont deem it an important medical issue.

    I worked at the ER at Darnall Army Medical Center when I was stationed at Fort Hood, Texas and there were SEVERAL infants and small children being brought into the ER by their parents for a fever or something as small as the baby sneezed a few times and now won’t he/she stop crying. I would always ask the parents if they gave their child motrin or another fever reducer before coming in and in 2 years of work there, 95% of the time the answer was no. So now the child sees a doctor, who will most likely put the child on a medicine they dont need and that type of prescribing leads to what we’re discussing right now. I would think young children and infants are especially at risk for this type of abx resistance because of the way doctors hand out candy in today’s world. It wasn’t quite like that when I was a child. I wasn’t on abx unless I had a legit reason–not after a few sniffles and a cough. But I thinhk we should be especially worried about our children because the younger you are, the more abx you take, the higher the chances are that you become resistant at some point in life.

    • I would always ask the parents if they gave their child motrin or another fever reducer before coming in and in 2 years of work there, 95% of the time the answer was no.

      Welcome to Parenting 101: when you feel the need to take the kid to the doctor, because the kid cannot go to Kindercare, NEVER give the kid a fever reducer prior to the appointment! You wouldn’t want to be perceived as a complainer now, would you?

  3. I can’t tell whether you’re critisizing me for saying that or if you agree with it. I see absolutely nothing wrong with a parent giving their child an age appropriate fever reducer before coming into the ER if their only symptom is a fever. McNeil doesn’t produce children’s motrin and sell it in every pharmacy in the country for no reason!!

    Nurses and doctors at Darnall complained about this A LOT. When a parent brings a child with a 99.4F low grade fever into the ER (and that’s the ONLY symptom)–they’re essentially paying the hospital the $500 deductable they have on their extremely costly health insurance policy in order for an RN or BSN to hand them the same amount of Motrin they could have bought for $4.99 at the pharmacy right down the street from their house. I had to be at the hospital for 12hrs a day for 4 days anyway, so it never really started to bother me until I would see the children with these fevers running around the ED waiting room like they’ve never felt better, some of them even asking their parents, “When can we leave?”, THEN having to listen to the parents complain that it’s taking so long for the child to be seen by the doctor because, “it’s just a fever”.

    • I was being a little bit snarky, but not directed at you. There is huge pressure on health care givers to provide antibiotics for many maladies that don’t require them on the part of parents. I can fully admit that I’ve been there too, but fortunately I’ve frequently had a job that has enabled me to have some measure of family leave time to accommodate waiting for a sick kid to get better.

      • Well, I’d also be willing to bet that you knew more than enough about medicine by the time your kids were born to be able to determine when you needed to panic and when there was no cause for panic if the situation came up where one of your kids got sick. Most parents that majored in something that’s not related to healthcare at all just panic as soon as their kids temp goes above 98.9F. I really think that maybe Pharmacists should be given more liberties than they are. They’ve gone to school for the same amount of time as a doctor. More so than the doctor the pharmacist knows effects of medicines on kids and adults so they should be given some type of liberty with helping parents to determine whether or not they want to take the kid fo an ER for a 99.3F fever or if they should just take the child home, give them Motrin, and see if the fever subsides. Parents get into this panic that they HAVE to hear a health professional tell them their child is alright. Well, a pharmacist is a health professional.. some type of patient care should be integrated into their training in their doctoral program so that they are able to diagnose minor fevers… they should be taught the signs of illnesses more serious so they can then refer the patient to a doctor. It may help the over-crowding of ER as well.

  4. But back to the subject at hand…. for hospitals who see the children with fevers, sometimes unnecessary medicines are prescribed and that situation right there leads to exactly what you’re talking about in your original post…. resistance!

    I do have a question concerning this topic, but with a different medicine… a chronic pain patient starts off with Vicodin, takes it for a couple months, then notices it doesnt work as well as it did the first couple of times he took it. He tells his doctor that and the doctor gives him Norco and tells him to take 2 every 4 hours.. 6 months later that doesnt work anymore, so the doctor gives him Percocet. A year or so down the line, that stops working and the doctor prescribes him Oxy Contin……etc. Is this progression relating to tolerance the same principle as the kind of resistance you’re talking about in this post?

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