For patients with multidrug-resistant infections, an infectious diseases consult may prove lifesaving, a recent study found.
Past studies have found that infectious disease consultation was associated with lower mortality, particularly for patients with Staphylococcus aureus bacteremia, but lead author Jason Burnham, MD, wanted to see if this was true for various multidrug-resistant infections.
His research team used data from 4,214 patients who were hospitalized from 2006 to 2015 at Barnes-Jewish Hospital in St. Louis to assess the association between consultations on six categories of multidrug-resistant infections (five different groups of bacteria and a polymicrobial group) and mortality.
For patients with resistant S. aureus, Enterobacteriaceae, and polymicrobial infections, those who were seen by an infectious diseases physician had 30-day mortality rates that were about 50% to 60% lower than those who were not, according to results published online on March 15 by Open Forum Infectious Diseases. Also, at one year, there was about a 25% reduction in mortality for patients with S. aureus and Enterobacteriaceae. (There were no mortality associations for resistant Pseudomonas, Acinetobacter, or Enterococcus, possibly due to small sample sizes.)
Dr. Burnham, an instructor in medicine at the Washington University School of Medicine in St. Louis, recently spoke with ACP Hospitalist about the findings.
Q: What led you to study this issue?
A: As an infectious disease physician, I see people with these multidrug-resistant infections in the hospital all the time. Even though I'm trained in this and this is what I do every day, it can still be challenging to manage these infections. There are few treatment options for multidrug-resistant infections, and patients often have many other medical comorbidities for which they take drugs that can interact with antibiotics. For multidrug-resistant infections to be challenging to a board-certified infectious diseases physician, it seems like these infections would be almost impossible to manage if you didn't have training in this area.
Q: Were you surprised at the results?
A: Honestly, not really. I know how challenging it can be to manage these patients. It's not necessarily just matching up what antibiotic the bacteria tests susceptible to. There are many additional factors to consider that people who aren't trained in infectious disease just are not thinking about. It's not their fault; that's not their training . . . and it would be silly for us to expect non-infectious disease physicians to be able to keep up with all the intricacies of multidrug-resistant organism treatment.
Q: Why do you think infectious disease consults had such a dramatic effect on mortality?
A: This study wasn't directly designed to answer that question, but it's something that we plan to look at as an extension from this project. However, I do have some hypotheses which we are going to test. My hunch is that infectious diseases physicians are more likely to recommend not only the correct antibiotic, but the correct dose and duration, simultaneously making sure that the antibiotic does not interact with other medications the patient is taking. In addition, because some antibiotics require monitoring of blood levels, I suspect that when an infectious diseases physician is involved, the target drug levels are achieved more frequently.
Another big aspect of complicated infection management is figuring out where the bacteria are hiding. I'll take, for example, S. aureus. Whenever we see that, we worry about what things the patient has that they weren't born with: Do they have an artificial hip? Do they have an artificial heart valve? Do they have a vascular stent? Staph can stick on all these things, and people may see it in the blood and think, “OK, well, they have a bloodstream infection, that explains why they are ill,” not recognizing that the root source must be identified. We often suggest additional imaging to look for abscesses that could be drained. . . . We know that when we see [S. aureus bacteremia], we need to look for infections on the heart valves, so getting an ultrasound of the heart is something that infecious diseases physicians recommend that might not be thought of otherwise.
Q: What are the main takeaways of your study for hospitalists?
A: I think if they see a bacterium that's resistant to three or more classes of antibiotics, they should give infectious diseases a call, and based on our study, there is a high probability that we will offer beneficial advice. . . . The take-home message is call whenever you're uncomfortable, but for bacteria that are resistant to three or more classes of antibiotics, it's definitely a good idea.
Q: How does timing of the consult come into play?
A: In our study, we excluded patients who died within the first 48 hours of the time that a culture was drawn. . . . It's unlikely that anyone is going to make a significant difference in that short time period. But in other studies, not of multidrug-resistant organisms specifically, there has been an association with an earlier call to an infectious disease physician and better outcomes, so I think that probably applies here, as well. In fact, if an infectious diseases consult is called late in the hospitalization, it may end up prolonging the hospital stay. We often have to set up intravenous antibiotics at home and make sure antibiotic levels are therapeutic, that source control has been achieved, and that follow-up cultures are negative (if applicable). All of these things take time, so the earlier you call us, the better. On the other hand, it is better to call late than not at all.