ATS Guidelines on the Diagnosis and Treatment of Adults With CAP

A multidisciplinary panel conducted reviews of research on the diagnosis and treatment of adults with Community-acquired Pneumonia. The panel reviewed 15 areas for recommendations. While some recommendations are unchanged compared with the previous 2007 official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America, the results from new therapeutic trials and epidemiological investigations led to revised recommendations for treatment strategies and management decisions.¹

Grant Waterer, MBBS, PhD, MBA, is the director of clinical services at East Metropolitan Health Service, the director of clinical services at Royal Perth Bentley Group, a professor of medicine at the University of Western Australia, an adjunct professor of medicine at Northwestern University, Chicago, an adjunct professor of medicine at Curtain University, and an adjunct professor of medicine and health sciences at Edith Cowan University.  

He answered questions on the updates made to the official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America.

Consultant 360: What updates have been made to the recommendations regarding the diagnosis of adults with community-acquired pneumonia (CAP)?

Grant Waterer, MBBS, PhD, MBA: The main change in the new guidelines is that we have recommended abandoning the category of health care-associated pneumonia.¹ This was because there is evidence that there has been a vast amount of overuse of broad-spectrum antipseudomonal and anti-methicillin-resistant Staphylococcus aureus (MRSA) therapy without evidence that these pathogens were ever present and without evidence that this practice has improved patient outcomes. On the contrary, there is evidence that outcomes are worse with this approach.

Instead, we strongly recommend that clinicians must establish whether these are problematic pathogens in their local setting, either through existing data or by collecting data prospectively in patients receiving broad-spectrum antibiotic therapy.

C360: What strains of bacteria cause CAP, and does the strain affect treatment choice?

GW: There are possibly more than 100 different bacteria that can cause CAP, but by far the most common remains Streptococcus pneumoniae. Far behind S pneumoniae, other common pathogens are Haemophilus influenzae, Staphylococcus aureus (both “normal” and methicillin-resistant strains), Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Legionella (of various strains), Mycoplasma pneumoniae, and Chlamydophila.

Most of the common bacteria are covered by the combination of a β-lactam and a macrolide or by a respiratory fluroquinolone. However, some are not, such as MRSA and P aeruginosa. Equally, in some parts of the world, there are different bacteria that are much more common and need different antibiotics—for example, Acinetobacter in Southeast Asia and Australia.

C360: What updates have been made to the recommendations regarding considerations for inpatient vs outpatient care in the treatment of adults with CAP? 

GW: The new guidelines are very consistent with the past guidelines in terms of using a scoring tool, like the pneumonia severity index (PSI) or the Confusion-Urea-Respiratory Rate-Blood pressure-65 (CURB-65), in additional to clinical judgement. Perhaps a slight nuance is that the PSI is currently preferred over the CURB-65 because more data is available on the former’s validity in this context.

C360: What updates have been made to the recommendations regarding the treatment of adults with CAP who test positive for influenza?

GW: The new guidelines recommend adhering to the Centers for Disease Control and Prevention guidelines for influenza management. However, given the significant proportion of patients who have a bacterial coinfection with influenza in the context of radiological pneumonia, the guidelines stress the need to continue to use empiric antibiotic coverage, at least for the first 48 hours until microbiological results are known.

C360: Are there any other updates that have been made to the recommendations regarding the treatment of adults with CAP? Why were these updates made?

GW: The largest addition to the guidelines is the recommendation regarding corticosteroids. Based on available evidence, the guidelines recommend against routine use of steroids in patients with CAP. We found no convincing evidence of benefit and some potential for harm, and these findings have since been further reinforced by availability of the US Veterans Affairs Extended Steroids in CAP study results.² While it is possible there may be a small subset of patients who benefit from steroids, that is yet to be defined. Overall, it is not recommended to give steroids. This is particularly important given the recent developments with COVID-19, that the use of steroids should not extend into other causes of pneumonia.

The guideline now has a specific recommendation on follow-up radiology, which is to not routinely do chest radiography scans on all patients who have had pneumonia but to follow the screening guidelines for lung cancer.

The guidelines are now much clearer on not exceeding 5 days of antibiotic therapy unless there is a clear clinical indication, as there is abundant data that this is sufficient in most cases of CAP.

As already noted, the guidelines now recommend sputum and blood samples be collected in the setting of severe CAP in patients admitted to the intensive care unit and in the setting of suspected or possible resistant pathogens, such as MRSA or Pseudomonas. The major guidance provided as to when to suspect these pathogens is prior culture (in the case of both) or bronchiectasis or severe chronic obstructive pulmonary disease (in the case of Pseudomonas).

C360: Where are the key knowledge gaps, and what research still needs to be done on the treatment and diagnosis of adults with CAP? What’s next for research?

GW: The optimal therapy of severe CAP is still unclear, and we need a proper randomized controlled study of β-lactam/macrolide combination against β-lactam/fluroquinolone.

The role of the newer diagnostic panels that have become much more available because of COVID-19 is also currently unclear, and we need a lot more research into their accuracy and utility, especially with respect to whether it is ever reasonable to withhold antibiotic therapy in the setting of positive viral tests.

Although not addressed in the guidelines, the increasing evidence of adverse long-term sequalae of CAP—including increased mortality over the subsequent 2 to 3 years and higher rates of myocardial infarction, stroke, and heart failure over the same period—are a major cause for concern. Significant research is needed in this area to avoid the substantial mortality and morbidity in CAP survivors.

Cheaper, faster, and easier-to-use diagnostic technology, especially at the point of care, is even more important now that COVID-19 is endemic.

The use of radiological modalities other than chest radiography, such as computerized tomography scanning and ultrasonography, is also a significant area of research interest at the moment, and it may well be in the next 5 to 10 years as we move away from chest radiography as the gold standard for the diagnosis of pneumonia.

C360: Is there anything else you would like to add?

GW: The guidelines were a large body of work, taking more than 3 years, from many experts, and I would like to thank them all for their contribution, especially Dr Ann Long, who was our primary methodologist, and Dr Josh Metlay, who was the chair of the Infectious Diseases Society of America.

1. Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia. An official clinical practice guideline of the american thoracic aociety and infectious diseases society of america. Am J Respir Crit Care Med. 2019;200(7):e45-e67. https://doi.org/10.1164/rccm.201908-1581st
2. Extended Steroid in Use in Community Acquired Pneumonia (CAP)(e) (ESCAPe). ClinicalTrials.gov. Published January 25, 2011. Updated October 8, 2020. Accessed September 27, 2021. ClinicalTrials.gov identifier NCT01283009. https://clinicaltrials.gov/ct2/show/NCT01283009