<i>Pseudomonas</i> Infections in the ICU: Who's Susceptible?

Peter L. Salgo, MD: Thank you for joining us for this Contagion^® Peer Exchange^® entitled, “Battling Against Resistant Pseudomonas Infections in the ICU.” Multidrug-resistant strains of Pseudomonas are increasingly found in hospital intensive care units, putting patients who are already very sick at risk for developing hard-to-treat infections. Timely diagnostics and effective empiric strategies are essential to the successful treatment of these infections. This Peer Exchange^® panel of experts in infectious disease will discuss current diagnostic and treatment strategies and best practices for antibiotic selection for resistant Pseudomonas.

I am Dr. Peter Salgo. I’m a professor of medicine and anesthesiology at Columbia University College of Physicians and Surgeons. I’m associate director of Surgical Intensive Care at New York-Presbyterian Hospital. Joining me for this panel discussion are Dr. Yoav Golan, an attending physician at Tufts Medical Center in Boston, Massachusetts; Dr. Marin H. Kollef, professor of medicine and the Virginia E. and Samuel J. Golman Chair in Respiratory Intensive Care Medicine at Washington University School of Medicine, and director of both Clinical Care Research and Respiratory Care Services at Barnes-Jewish Hospital of St. Louis, Missouri; Dr. Jason Pogue, an infectious diseases clinical pharmacist at Sinai-Grace Hospital of Detroit Medical Center and clinical assistant professor of medicine at Wayne State University School of Medicine in Detroit, Michigan; and Dr. Andrew Shorr, section head of Pulmonary and Critical Care Medicine at MedStar Washington Hospital Center, and professor of medicine at Georgetown University in Washington, DC. I want to thank all of you for being here. We have a lot to cover, so let’s begin.

The obvious question is, who are the patients in the ICU who are most susceptible to Pseudomonas aeruginosa infections. We can just call them Pseudomonas, right? We don’t have to give the full name. Where do we start on this?

Marin Hristos Kollef, MD: Well Peter, the sickest patients are usually the ones who get Pseudomonas infection. In the intensive care unit, there are certain categories of patients who seem to be at higher risk. Certainly, patients who are immunosuppressed fall into one of those categories. At our institution, we happen to have separate ICUs, including an ICU for patients who have bone marrow transplants and certain malignancies. We certainly see a lot of Pseudomonas within that population. There are other critically ill patient groups where we tend to see Pseudomonas as well. We run a very large lung transplant program, and we have a large cystic fibrosis program. Patients who have structural lung disease, in particular, seem to be at very high risk for developing Pseudomonal infections. Obviously, other patients who have certain disruptions of skin—burn patients, etc&mdash;fall into that category as well. One thing that is important to keep in mind is that many of these patients have 1 common factor in place, and that’s having received prior antibiotics. These critically ill patients are often getting antibiotics, and for that reason, it can predispose them to infections, particularly with resistant bacterial like Pseudomonas.

Peter L. Salgo, MD: But I was always taught that it isn’t the Pseudomonas necessarily, but that Pseudomonas are actually a marker for really serious disease. The Pseudomonas, per se, are not all that virulent. Is that fair? Is it Pseudomonas that are causing the illnesses, or is it the illness that’s leading to Pseudomonas?

Jason Pogue, PharmD, BCPS-AQID: I would say Pseudomonas is a virulent organism.

Peter L. Salgo, MD: How so?

Jason Pogue, PharmD, BCPS-AQID: If you look at just the virulence factors. But you’re absolutely right to add in the fact that it hits our most vulnerable patients and it has the highest likelihood of having drug resistance, so we’re most likely to get it wrong up-front. Sometimes we’re forced to use suboptimal therapies on the back end as well. So, it all plays hand-in-hand, but it certainly has its virulence factors as well.

Peter L. Salgo, MD: Certainly it does, but what I’m saying is, as you point out, the sick people—the weak, the immunocompromised, the previously treated, the ones who can least afford to get a virulent infection&mdash;they get the Pseudomonas.

Yoav Golan, MD: In many cases, as Jason says, getting infected with Pseudomonas would be the turning point. You mentioned cystic fibrosis. Many patients actually do well until they get colonized with Pseudomonas, but once they do, they start getting infected. So, you’re right, you need a predisposing factor sometimes. But then, Pseudomonas may be the factor that would actually result in a patient’s decline.

Andrew Shorr, MD: The other point I think is important is that we’re using a paradigm right now, this part of the conversation where we’re presuming the Pseudomonas are an ICU-acquired phenomenon. The vast majority of ugly Pseudomonas is brought to me from the floor, where antibiotic therapy has been misused, such as 20 days of piperacillin/tazobactam because a patient has an ingrown toenail.

Peter L. Salgo, MD: You don’t do that? That’s not a good idea?

Andrew Shorr, MD: No, probably not.

Andrew Shorr, MD: Actually, in our place, it’s actually in the Jell-O on the tray for patients.

Peter L. Salgo, MD: But we were told to never stop the antibiotic too soon.

Andrew Shorr, MD: With that, there’s a whole host of evidence now, and we’re going to drag pseudomonal therapy into the evidence-based literature paradigm at some point. But the other point is, I see plenty of patients with classically health care-associated syndromes where they come from nursing homes, they’ve probably been in the hospital recently, they’ve probably seen prior antibiotics, and they bring their multiresistant pseudomonas with them to the hospital. So, I think it’s important to realize that although there’s plenty of ICU-acquired Pseudomonas, there’s plenty of de novo Pseudomonas infection that’s brought to the ICU. You have to be vigilant about it, not only as an ICU-acquired pathogen but also just as a pathogen in sick patients.