Klebsiella and the Club of Antibiotic Resistance

Wee Beasties

In this episode, Dr. Kimothy Smith and Christian Railsback discuss Klebsiella – a gram-negative bacteria that causes various healthcare-associated infections. Though Klebsiella has a broad scope at the species and sub-species levels, this episode concentrates on common characteristics, environments, and levels of drug resistance. A transcript of the conversation appears below.

More about Klebsiella:CDC’s Opportunistic Pathogens of Premise Plumbing listKlebsiella pneumoniae in Healthcare SettingsKlebsiella Pneumonia

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***SHOW TRANSCRIPT:

Christian: I am back with Dr. Kimothy Smith. Kimothy, welcome back!

Kimothy: Thanks, Christian.

Christian: So, what’s our bug for today?

Kimothy: Klebsiella.

Christian: Klebsiella. Reminds me of something I would get whacked with by my grandmother.

Kimothy: Well, Christian, Klebsiella is likely slightly more insidious than your grandmother, it can lead to meningitis. But I don’t know I never met your grandmother.

Christian: You’re right, that’s slightly more insidious than my grandmother. Okay, I’m really interested to hear how Klebsiella leads to meningitis or other pathologies of similar mortality and morbidity. But let’s start small today. Let’s make this easily digestible. This is a waterborne pathogen like the previous pathogens we’ve discussed. How do we differentiate this bug?

Kimothy: Let me first say the genus, Klebsiella, has a fairly broad scope and extensive list at the species and sub-species levels. For the purpose of remaining very clear I’ll limit my descriptions to the most clinically significant species and sub-species. Namely, K. pneumoniae and K. oxytoca. Both of which can be pronounced in different ways, by different people. Part of the justification for limiting to just these two is that 90% of the waterborne pathogen infections caused by Klebsiella are these two species.

Christian: Okay, so that means the microbiologists out there are going to express scorn for our unwillingness to spend the full day discussing the catalogue of attributes across the genus, right? So, keeping in mind this is a 30,000’ discussion, what’s at the cellular level, what kinds of characteristics stand out?

Kimothy: Well, Klebsiella’s most immediate visual cue is its rod-shape and capsule. Its capsule is meant, in part, to protect it from hostile environments. Klebsiella thrives in the gastrointestinal tracts of a wide range of animals, including our own. And consequentially it’s also found in wastewater, soil, and then of course therefore, fruits and vegetables as well. Since it predominates these areas, it easily integrates into the water cycle and in particular municipal water networks. The capsules also promote biofilm development which allows it to better protect itself and easily persist in water distribution systems despite heavy chlorination. Like the other pathogens we’ve discussed this too is a gram-negative bacterium. And it’s non-motile, so it really depends on the biofilm for protection and nutrients.

Christian: Biofilms keep coming up. I assume it’s not a coincidence that the CDC is emphasizing non-motile biofilm producers on its list of most concerning waterborne pathogens?

Kimothy: Yes, that’s right, Christian. And I’ll just add that another common feature we’ll begin to see many of these bacteria share is the ability to resist antibiotics. Klebsiella is no exception. It is among the most resistant to antibacterial agents. Most recently to a class of antibiotics known as carbapenems.

Christian: This is I suspect, in part, why we see so many healthcare-associated infections resulting from Klebsiella. Long-term care facilities, hospitals, clinics, and places where antibiotics are used, I imagine that’s why Klebsiella persists so much. So, tell me a little about the epidemiology. What kinds of illnesses are caused?

Kimothy: So, I mentioned earlier that Klebsiella does exist in the human GI tract, but this does not cause disease. Klebsiella really only becomes a problem when it’s (like meningitis) transmitted in the blood or inhaled. So, serious blood infections and acute pneumonia are the biggest concerns. Particularly, patients needing long-term, recurring infusions or patients on ventilators are most susceptible. Also, individuals with liver disease and are hospitalized are known to get liver abscesses as a result of Klebsiella.

Christian: Okay, so if I’ve got this right, I’ve got Klebsiella in my gut right now, but it’s essentially benign there because it really can’t take root and cause disease, but if it’s in my blood or if it enters my lungs that’s really where things start to go badly. So, I’ve seen some headlines, well more headlines than one would expect, highlighting Klebsiella outbreaks around the United States. Why do you think there has been a spike in outbreaks? Is this in some way correlated to our overuse of antibiotics in healthcare settings?

Kimothy: Insightful question, Christian. Klebsiella is ubiquitous in the environment. It finds its way into many places where humans will run into it, and of course, one of those places is hospitals or healthcare centers. But your point highlights the importance of antibiotic stewardship, or the judicious use of antibiotics to fight bacterial infections in healthcare settings. One of the interesting features of gram-negative bacteria, like Klebsiella is that they can share genes – they can share plasmids. In these plasmids they can carry antibiotic resistance genes that can be shared with other bacterium – passed on from one group to another. And so, when they grow, the resistance to antibiotics can grow exponentially. Bacteria can carry, and “collect” multiple antibiotic resistance factors in their DNA, which makes them hugely dangerous, particularly in a healthcare setting where you have immunosuppressed patient populations.

The topic of antibiotic stewardship has reached a level of importance to warrant discussion and policy adoption at the World Health Organization (WHO). Even some at CDC and Health and Human Services consider this an issue that deserves a broader national discourse in the United States.

We have a limited number of antibiotics with which to fight infections, and we are losing many of those options because of the way the bacteria are adapting. Consequently, it is harder for pharmaceutical companies to develop novel antibiotics. I didn’t intend to wax so philosophical on this topic, but you brought up such an important issue, I wanted to give it the attention it deserves.

Christian: I really appreciate it. It seems to me this is a problem we are not well prepared to mitigate. Namely, you’ve got a waterborne pathogen here that has a rigid exterior, it’s protected in a biofilm, it’s resistant to the effects of chlorination, it’s ubiquitous in water supplies, and there is no way to mitigate it from entering our water supply; and, to top it all off it’s incredibly resistant to antibiotics while outpacing our ability to manufacture better antibiotics. It seems like we’re getting outmatched here and one of the things we could be doing better is monitoring water using biosurveillance.

Kimothy: Absolutely, I couldn’t agree with you more. Better surveillance, better detection and diagnostics, particularly at the point of care / point of need, combined with fastidious cleanliness and sterilization in healthcare settings, and judicious use of antibiotics in healthcare settings. And finally, sharing this information across healthcare provider networks – educating communities.

Christian: Yeah, I couldn’t agree with you more, education seems to be the best thing we could do to begin the fight. Again, this fascinating stuff, Kimothy. What else do we need to mention today?

Kimothy: I think that’s probably it. I think we’ve scared our audience today – hopefully not too much. We’ve given some hope and some appropriate measures to take, so I think that’s enough.

Christian: Well, again, thanks so much! This is always a pleasure.

Kimothy: Likewise, Christian.