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Todd A. Florin, MD, MSCE: Hello. I am Dr Todd Florin and welcome to the Medscape InDiscussion podcast series on pediatric pneumonia. Today we'll discuss complicated pneumonia: what it is, how to diagnose it, and how to manage it.
First, let me introduce my guest, my friend Dr Debra Palazzi. Dr Palazzi is medical director of the Antimicrobial Stewardship Program at Texas Children's Hospital and a member of the Pediatric Infectious Diseases Society's Pediatric Committee on Antimicrobial Stewardship. In addition, she participates in the Sharing Antimicrobial Reports for Pediatric Stewardship (SHARPS) Group, a collaborative of more than 30 children's hospitals focused on establishing best practices for the use of antimicrobials in children. Dr Palazzi is director of the Pediatric Infectious Diseases Fellowship Program and Associate Division Head of Pediatric Infectious Diseases at Baylor College of Medicine. Welcome to InDiscussion.
Hi, Deb. How are you doing today?
Debra L. Palazzi, MD, MEd: I'm doing great. Todd. Thank you so much for having me.
Florin: I like to ask all of my guests on this series about the changes in medicine over time. What do you think is one of the biggest or most important or most influential changes that you've seen in practice over your time as a pediatric infectious diseases physician?
Palazzi: I really can't emphasize enough the serious and pervasive problem of antimicrobial-resistant bacteria in our practice now. That's part of the reason I have the passion for antimicrobial stewardship and direct the program where I am. I really think everything we can do to combat this problem is critical.
Florin: I am totally in agreement with that. I think there is a reason why President Obama called this one of the major global threats in our society and why people like you are working so hard to combat this critical problem in our world today.
I think we should segue directly into our discussion on complicated pneumonia. Before we even talk any further, I think it's really important to define complicated pneumonia. There are a lot of definitions in the literature. How would you define complicated pneumonia for our listeners?
Palazzi: When I think of complicated pneumonia, I generally define it as pneumonia that is accompanied by any of the following: pneumonia with loculated parapneumonic effusion, empyema, necrotizing pneumonia, pneumonia accompanied by lung abscess, and rarely, pneumonia that was accompanied by pneumothorax.
If you think of pneumonia more systemically, some people would use the definition of pneumonia accompanied by septic shock as complicated pneumonia or pneumonia that ended up requiring extensive intensive care. That's almost a different entity and probably not what we're going to focus on today. For the purposes of this discussion, when I'm talking about complicated pneumonia, I'm going to be focusing on that which is localized to the lung and the chest cavity.
Florin: In a previous podcast episode of this series, we've talked about uncomplicated or routine pneumonia and what organisms are most responsible for that in in children. What organisms do we worry about in complicated pneumonia? Does it really differ from uncomplicated pneumonia? When we think about etiology for complicated pneumonia, we also think potentially about some subtle differences between those organisms that can cause parapneumonic effusion or parapneumonic empyema and those organisms that could lead to a lung abscess or necrotic lung disease.
Palazzi: Yes, I think there are some similarities in terms of organisms and etiologies and then some distinct differences that we should talk about. When we're talking about the common etiologies of complicated pneumonia, just like uncomplicated pneumonia, Streptococcus pneumoniae is at the top of the list. That's partly because, as everybody knows, with routine vaccination, we have for sure affected a lot of the serotypes that can cause complicated pneumonia. There are a multitude of other serotypes that can still be implicated that are not present in our vaccines. That organism is still very high on the list. Other organisms to consider for complicated pneumonia include Staphylococcus aureus. That is going to be more common with necrotizing pneumonia and lung abscess, but it very often happens with loculated parapneumonic effusions as well.
Depending on the host and the presentation, we really need to expand the list of potential pathogens. For example, in patients who are at risk for aspiration, who develop lung abscesses, I would include anaerobes as etiologies of complicated pneumonia. They are often not present as the only pathogens. Typically, that's a polymicrobial infection. Depending on risk factors, you might include gram-negative pathogens as etiologies of lung abscess. Then, uncommonly, you perhaps could have some atypical organisms as well.
Florin: That's a great summary. The one major contrast that we should note for our listeners between complicated and uncomplicated pneumonia is, as discussed in previous episodes, viruses are really a predominant organism in uncomplicated pneumonia, particularly in younger children. It's worth noting specifically that in complicated pneumonia, it would be highly unlikely for a virus to result in complicated pneumonia, and if you have a patient with complicated pneumonia, you really do need to be thinking about bacterial, both typical and sometimes atypical, etiologies.
Perhaps the next thing that we should go into is diagnosis. Since we were just talking about etiology, I think the natural next step would be to talk about laboratory testing. The first decision point seems to be, do we obtain fluid from the parapneumonic cavity to help with the diagnosis? Once we do obtain that fluid, what laboratory testing do we need to perform on that specimen?
Palazzi: That's a great question. There is strong literature on the adult side to suggest that the Light's criteria are useful for the diagnosis and treatment guidance in adults with parapneumonic effusions. As a reminder, the Light's criteria look at the effusion vs serum protein ratio or the effusion vs serum lactate dehydrogenase ratio. Depending on the ratio, you can see whether or not you have a transudate or an exudate.
What's important to know is that this is helpful in adults because adults have many different etiologies of parapneumonic effusions other than infection. For example, cancer is going to be much more common. In children, that's not really the case. In fact, in children, the Light's criteria have not been properly validated, and so their routine use is not recommended. I wanted to mention that just because I think that people may be unaware that those data can potentially lead you in the wrong direction in a child, so you really should not use them.
What is helpful to send the fluid for in a child where you sample it? I'm an infectious disease doctor, so I'm going to tell you to get a culture of that fluid every time. Cultures are important for multiple reasons. One, to identify the pathogen, and two, to provide the susceptibility data. We've talked about the importance of antimicrobial stewardship and that susceptibility data is going to really help us drive our ultimate choice of antimicrobial and allow us, hopefully, in the majority of cases, the opportunity to narrow the spectrum in terms of the agent that we use. That's very important.
As we know, many of these children, however, get started on broad-spectrum antibiotics appropriately before they have that fluid sample. Cultures may or may not yield the etiology. In selected patients or depending on your hospital setting, molecular diagnostics have become a lot more useful for establishing the diagnosis. At my institution, we have an in-house assay that's been validated and can provide us information about the most common gram-positive organisms that are implicated in complicated pneumonia. For certain pathogens, this can be the final answer as well. For example, with Streptococcus pyogenes, which is universally susceptible to penicillin, if I know that that's my etiology, then I'm done and I can narrow my agent appropriately.
Florin: There's also a time benefit to using polymerase chain reaction (PCR) or molecular diagnostics over culture as well.
Palazzi: There can most certainly be a faster turnaround time using PCR, within hours to less than a day compared with 48 hours or sometimes more to get that susceptibility data from a culture. The downside, as you know, can potentially be the cost and then also having a validated assay that is available.
Florin: What I hope is that as molecular testing becomes more widespread, the cost will come down and the availability will increase. We'll have to see how that progresses over time.
Now that we discussed culture and or molecular diagnostics on the fluid obtained from the pleural cavity, what about blood cultures?
Palazzi: In patients with severe pneumonia and complications, such as we're discussing in this episode, that blood culture does still play a role. You can often identify the organism without having to do invasive sampling. Now, the invasive sampling might still be necessary to get that pleural fluid from a therapeutic standpoint. But for diagnostics, the blood culture can give you your answer. This is a different scenario from uncomplicated bacterial pneumonia, where we no longer recommend blood cultures because the utility is pretty low in terms of yield.
Florin: I do think that's an important distinction. A lot of what we talked about with laboratory testing was about trying to identify the organism so that appropriate therapy can be narrowed and directed toward the organism, causing the patient's pneumonia.
Before we start talking about treatment, I want to talk a little bit about diagnostic imaging. We had another episode of this podcast where we discussed point-of-care lung ultrasound for the diagnosis of uncomplicated pneumonia. What are the best imaging studies to diagnose and manage complicated pneumonia? There's definitely been a lot of literature about ultrasound. However, I think a lot of clinicians still obtain CT scans for complicated pneumonia. What does the evidence say?
Palazzi: I think the evidence has come down pretty strongly, suggesting that ultrasonography is the preferred first step in evaluating the patient with complicated pneumonia, as suggested by your initial physical exam and your plain radiograph findings.
I still think there is a role for CT. Depending on the ultrasound findings and the severity of illness of the patient, chest CT may be needed for those patients that are either failing to respond to what you've done initially with ultrasound and in those who need further characterization of the disease process, especially those patients where you're considering a more invasive surgical procedure such as video-assisted thoracoscopic surgery (VATS). I think there's a role for CT scans. Maybe using the Pareto principle, or the 80/20 rule, that the 20% who aren't following the rules may still benefit from it. We do need to emphasize, however, that the first preferred step with advanced imaging is ultrasound.
Florin: The goal, of course, is to avoid as much ionizing radiation as we can. We know, even with the Image Gently criteria that a lot of pediatric institutions use for their CT protocols, that it still is a big dose of radiation to the chest, to these young developing children and youth. Therefore, I think starting with that ultrasound, which avoids radiation altogether, sounds like (and I think evidence would suggest, as you had mentioned) [it should be the] first-line imaging study and potentially the only imaging that is needed in the majority of kids with complicated pneumonia, except for the situations that you described.
We've now talked about etiology, we've talked about diagnostic testing and diagnostic imaging. Now we should move into talking about the best treatment approach. With complicated pneumonia, there really are two facets of treatment. The first is antimicrobial therapy, and the second is physical drainage. Let's start with antimicrobial therapy. What is the best treatment approach, in terms of the antimicrobial choice?
Palazzi: Empirically, there's good agreement that using a third-generation cephalosporin such as ceftriaxone to cover strep pneumoniae, other gram-positive organisms, and potentially some of your respiratory tract gram-negative organisms is a good place to start — a reasonable first choice with the addition of an anti–methicillin-resistant Staphylococcus aureus (MRSA) agent such as vancomycin or clindamycin, depending on your local susceptibility data. That would depend on how concerned you are about that particular pathogen. In my setting, that is a concern. We would do dual therapy.
Of course, there is an alternative that is approved now for children that are 2 months of age or older. It's monotherapy, and that would be ceftaroline. That drug could cover streptococci and staphylococci with very good coverage, and that's a possibility. We tend, from an anti-microbial stewardship standpoint at my institution, not to start with that agent in the majority of patients from a broad-spectrum standpoint and also a cost standpoint. Depending on the patient and the presentation, you may consider adding additional agents such as azithromycin for atypical organisms. But really it would be on a case-by-case basis.
Florin: That sounds like a great starting point in terms of antimicrobial choice. I think over time, certainly in the amount of time that I've been practicing, I've seen a lot of variation in duration of antimicrobial therapy for complicated pneumonia. It feels like, depending on who you talk to and where you look, you see a bit of a different answer on this question. What would be some general recommendations about the duration of therapy for kids with complicated pneumonia?
Palazzi: That's one of our most common consult questions related to pneumonia as infectious disease experts. In fact, that is the consult question: How long do we do this? The unsatisfying answer is long enough. But what we know from experience, the literature, and individual patient care is that it is, generally speaking, a prolonged course. It starts off with intravenous therapy and source control. Source control and the patient's clinical pattern and course are what really determine how long the duration of therapy is. Most of the time, these children are going to end up being treated for somewhere between 2 and 4 weeks in total — again, depending on source control and defervescence. Some experts would recommend treating at least 10 days after the last fever. But that is not a uniform practice.
Florin: Are there criteria that you use to make the switch from intravenous antibiotics to oral antibiotics?
Palazzi: That's a very good question because I feel like the needle on that is moving down every year. It used to be that we did the majority of treatment for these patients as intravenous. We learned over time that if you have a fairly good bioavailable agent to switch to orally, if somebody has source control and they have defervescence and maybe if you prefer to check inflammatory markers and you see that those are starting to come down (because some people will use that as a parameter), then a more rapid switch to oral therapy is reasonable.
Florin: Great. The next facet of treatment after we've selected our antimicrobial agent is physical drainage of the plural cavity. When should we drain a parapneumonic effusion, and how do we drain it?
Palazzi: There are a couple of parameters I think about to push for drainage in these patients. The first might just be if there's a very large amount of pleural fluid. That could still be free-flowing because if that's such a large amount that it's causing some respiratory compromise, then it needs to be drained.
Florin: I was also going to ask how we define large amount. If there is so much fluid pushing on the lung that it is leading to respiratory compromise, respiratory distress, and hypoxemia, that I think is a clear answer in terms of draining. Are there other size criteria that you use to say, okay, it's time to get this fluid out of that cavity?
Palazzi: I think one definition that is used is that if you have an effusion that's occupying more than one half of the hemithorax, that's large. That can be considered for drainage even in the absence of respiratory symptoms. Some people would consider even moderate effusions as those that you would drain more typically when accompanied by respiratory symptoms. These are if they're free-flowing. Once you get to the point where you have a loculated effusion, most people would advocate for drainage at that point. Moderate to large loculated effusions should be pursued for drainage.
The final criterion I use is that if there's a general lack of clinical improvement after a reasonable period of initial intervention and antibiotic therapy — some people use 72 hours — then you might need to consider revisiting the question of either initial drainage or additional drainage.
Florin: What you've outlined is really helpful. We've talked about when to drain, and now the question is, how do you go about draining it? We have different options available to us. One is to do a thoracoscopy and put a chest tube into the plural cavity. Another option is to go to surgery and do video-assisted thoracoscopic surgery (VATS). What is your practice? What does the literature say about the best way to approach draining?
Palazzi: The literature is pretty clear that those two modalities are equivalent in terms of outcomes in children if they are performed in certain fashions. For example, if you place a chest tube and use fibrinolytics at the beginning for a complicated — as in loculated — effusion, that is not inferior to performing the VATS procedure. What we also know, though, is that a VATS procedure is more invasive and is accompanied by more discomfort for the patient, and oftentimes it takes a longer time to heal. For that reason, I think most people have moved in the direction of putting in a chest tube and using fibrinolytics as their first line drainage procedure.
Florin: This has certainly evolved over time. There are now a lot of different types of chest tubes on the market. There are the so-called pigtail chest tubes, which are soft, flexible, lower-bore catheters that are a bit less invasive to be able to insert and maintain. Then there is, of course, the traditional large-bore chest tube that we grew up with. Is there a preference in terms of the type of tube that goes into the space for drainage?
Palazzi: I think in children, people have moved toward the pigtail catheters almost exclusively — again, from a noninferior standpoint and an efficacy standpoint in terms of drainage, and also because they're much less uncomfortable. The patients can take bigger breaths; they can heal faster with those pigtail catheters vs the large-bore catheters.
Florin: The last question regarding chest tubes — and I'm sure that this is another favorite infectious disease consult of yours — is, when does the tube come out?
Palazzi: When it's time. That's actually a great question. I can tell you what we do in practice here. Surgeons and some of the groups here talk about having < 20-30 cc/d coming up out of the tube as the time to clamp it and see how the patient responds. I'll be honest, I'm not sure if that's highly evidence-based anymore or if the needle has moved on that. I'm curious to hear what you're doing at your institution.
Florin: That brings up the point that I don't think there is great evidence in terms of when to clamp and remove the chest tube. I think your answer of when it's time, though, said tongue in cheek is probably the most accurate answer for us currently. I do believe that the same standard of, once it starts draining < 20 or 30 cc/d, then the thought is, let's clamp and give a trial and see how the child does. Certainly I would agree with you that there is no evidence-based, definitive approach to that question.
We've talked a lot about draining the plural cavity for parapneumonic effusion and empyema. We started this conversation saying that other forms of local complicated pneumonia include lung abscess and necrotizing pneumonia. How should those be approached in terms of a physical drainage perspective?
Palazzi: Those are two examples of where I would not advocate for placement of a tube into those spaces because of the risk for bronchopleural fistula formation. In those patients, we try medical therapy as much as possible. In those patients in whom medical therapy fails (again, this is a very small minority of patients), we're talking about a special circumstance here; those patients might be considered for lobectomy. That is how you would control that source if you could not in any other way.
Florin: It sounds like for those patients especially, it's really a conversation between your infectious disease consultants, your surgeons, and potentially interventional radiology as well, to be able to determine the best treatment course for the individual patient in front of you.
Now that we've talked about the best treatment, I think what I'd like to close with are what you think are the most important future directions in this world of complicated pneumonia.
Palazzi: I'm biased. I'm an infectious disease person, so I think even more rapid diagnostics would be incredibly helpful: diagnostics that included rapid diagnostics, that included susceptibility data. And anything we can do to improve the field in terms of how fast we get those tubes out, how fast we transition patients to oral therapy, and decreasing the morbidity of the whole experience would be the next steps.
Florin: Thanks, Deb, for a great discussion on all facets of complicated pneumonia. I would like to thank you all for tuning in. Please take a moment to download the Medscape app to listen and subscribe to this podcast series on pediatric pneumonia. This is Dr Todd Florin for InDiscussion.
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Cite this: Diagnosing and Treating Complicated Pediatric Pneumonia: Common Missteps and Best Practices - Medscape - Aug 10, 2023.