Pseudomonas aeruginosa – Biofilm Producer and Pathogen

In this episode, Christian Railsback and co-host Dr. Kimothy Smith one another’s virtues and conduct a shallow dive into the molecular machinery, persistence, and epidemiology of Pseudomonas aeruginosa, the first of several waterborne pathogens discussed this season. A transcript of the conversation appears below.

More about Pseudomonas aeruginosa:
Infection risk, spread, and treatment
Drinking water and outbreak surveillance
Additional opportunistic pathogens of premise plumbing

Stay tuned for more episodes, posting on the first Thursday of each month. Subscribe to our show wherever you get your podcasts and find more info at weebeastiespodcast.com

The Wee Beasties podcast is a production of Nephros, Inc., a leading water technology company providing filtration and pathogen detection solutions to the medical and commercial markets.

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SHOW TRANSCRIPT:
Christian: I am here with Dr. Kimothy Smith. Kimothy, welcome!

Christian: Kimothy, you are currently the Vice President of the Pathogen Detection Systems division at Nephros, but you have a pretty rich history. Can you give our listeners a summary of your professional life and what you’re currently working on with Nephros?

Kimothy: DVM, PhD, Biodefense, Consulting, Academia/DRI, Nephros, Pathogen Detection in potable water systems.

Christian: So, the current technology that Nephros incorporates in its risk management portfolio identifies waterborne pathogens, but there must dozens, possibly hundreds of pathogens to identify? I imagine most people don’t know these pathogens by name; maybe they’ve heard them mentioned, but are likely not acquainted with the specifics -- cellular structure, diseases they cause, target populations which are vulnerable, and recent outbreaks, etc. This series is meant to share information about waterborne pathogens and make otherwise unpalatable information about microorganisms more accessible.

Kimothy: Yes, that’s right Christian. There is an entire catalog of pathogens and it can get overwhelming quickly. It’s difficult to know exactly where to start directing your attention. I thought we might start with pathogens that have been in the headlines as it pertains to outbreaks, but that people aren’t screening for or aren’t aware is a potential problem at all.

Christian: Great; what should we start with?

Kimothy: I was thinking Pseudomonas aeruginosa might be a good place to start.

Christian: I realize there are other species of Pseudomonas that are important, but, what kind of waterborne pathogen is Pseudomonas aeruginosa and what kind of infection does it cause?

Kimothy: This is a gram-negative, opportunistic pathogen, that can infect the blood and lungs and lead to pneumonia. It thrives in moist environments, so soil or water is where it’s most commonly found.

Christian: I’d like to get to the population of individuals most susceptible to this infection, but before we go there can you give everyone a sense of what type of bug this is at the cellular level?

Kimothy: Sure, it’s a motile, rod-shaped, gram-negative bacterium. It takes on a blue-green color when grown on a plate and has relatively low nutritional requirements. It can grow anaerobically, which means it does not use oxygen. It also produces a biofilm which combined with its highly adaptive environmental response makes this a fairly resilient bug. 

Christian: What do you mean by that?

Kimothy: Well, the cell can modify itself very quickly to an antimicrobial environment. The cell’s ability to modify its DNA (through mutation or from genes from other bacteria) allows it to resist most anti-microbial climates, while less robust microorganisms will die. The bacteria’s efficiency in rapid adaptation combined with being able to obfuscate itself in biofilms makes it very difficult to eradicate. It can also provide a home for other microbes to establish themselves and live. This is why we have seen this bug among the more rapidly trending outbreaks when it comes to nosocomial infections.

Christian: Okay, so nosocomial infections? These are infections that are acquired in healthcare environments, like hospitals, clinics, or long-term care facilities?

Kimothy: That’s right.

Christian: Okay, so let’s come back to my question from earlier – what kind of population of individuals are most susceptible to acquiring Pseudomonas aeruginosa?

Kimothy: Well, the bacterium takes advantage of the vulnerable epithelium (i.e. skin). That is, a patient that has degraded, or underdeveloped epithelial tissue is going to be highly susceptible to Pseudomonas aeruginosa. Babies in the PICU/NICU, for instance, or burn patients in particular. But anyone with a preexisting acute or chronic respiratory issue is also vulnerable. Ironically, since hospitals are where you find antibiotics and antimicrobial agents, antibacterial-resistant Pseudomonas aeruginosa strains find hospitals to be a favorable environment. Medical equipment, such as ventilators or catheters are good locations to harbor Pseudomonas.

Christian: I see, so given the persistent and lethal nature of this bug, why are we still seeing it as a problem not being addressed in hospitals and healthcare facilities? For example, we know that if water isn’t treated or filtered you can acquire cholera and die, so now we treat or filter the water and don’t get sick. Why isn’t the same approach taken to address Pseudomonas aeruginosa?

Kimothy: Here in the United States, there is not a strict regulatory requirement to test water for pathogens other than for Legionella, so many facilities don’t realize they have Pseudomonas aeruginosa in their water supply.

Christian: Couldn’t facilities just treat or filter the water without screening for it? In other words, isn’t it unnecessary to know what’s in the water if you implement methods to eliminate nosocomial infections, such as water treatment and filters?

Kimothy: I think unfortunately it’s slightly more nuanced than what you’ve described. Just like there is not one or two solutions your physician gives you when you go to the doctor when you’re sick, there is no panacea to treat building water networks. Just like a physician, if you want to practice good medicine and develop a sound patient care plan, you need to know what you’re dealing with before you start treating. Physicians run blood tests and take images -- x-ray, MRI, etc. We are doing something similar are Nephros. We are taking water samples and testing them using molecular assays and gene sequencing technology. This allows us to have, or give our clients, a clear picture of the building health. Treatment outcomes for the building – filters, UV, chlorine, copper, silver nitrate, etc. – largely depend on what we are diagnosing the problem to be.

Christian: So, Pseudomonas aeruginosa, for example, isolated to a burn unit or NICU, may require a more robust remediation strategy for an Infectious Disease staff than say E. coli or addressing certain coliforms?

Kimothy: That’s right, Christian. And may I add that what we’re doing is allowing the screening and diagnosis to occur in the field, on-site, which doesn’t confine clients to only using feedback from lab cultures – which can take several days or weeks to get results.

Christian: And that’s PluraPath you’re talking about there, correct?

Kimothy: Correct

Christian: Alright folks, well that was a nice little overview of Pseudomonas aeruginosa. We’ll see you next time for our next Pathogen Podcast here at Nephros. Thanks, Kimothy!

Kimothy: You bet; thank you, Christian.