Is Health Care-Associated Pneumonia (HCAP) Still Relevant?
"Rethinking pneumonia treatment in the age of antibiotic resistance."
Community-acquired pneumonia (CAP) remains a serious infection. However, despite medical advancements, accurately identifying the specific pathogens to effectively prescribe antimicrobial agents remains a challenge. Often, treatment decisions rely on experience and broad assumptions based on common etiologies.
Over the decades, the causes of pneumonia have shifted due to aging populations, increased vulnerability to illness, antibiotic selection pressure, vaccination strategies, and the emergence of new pathogens. Improved molecular diagnostic tests have expanded the array of detectable pathogens, revealing multiple pathogens present in many cases.
Once a clear distinction existed between the pathogens causing CAP and nosocomial pneumonia, but that distinction has blurred. Factors such as repeated hospitalizations in the elderly and those with chronic organ failure, increased numbers of vulnerable hosts in aged-care facilities, and the rise of ambulatory care programs have blurred the lines between hospital and home, impacting pneumonia treatment strategies.
The Rise and Fall of HCAP
In 2005, the American Thoracic Society (ATS) and Infectious Diseases Society of America introduced health care-associated pneumonia (HCAP) as a distinct category. This was based on the premise that certain risk factors identified patients at high risk of pathogens not covered by typical CAP empirical therapy. Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa were of particular concern, as they were becoming more common in patients from the community in tertiary centers in the United States.
- Limited Predictive Power: HCAP risk factors often fail to accurately predict the presence of drug-resistant pathogens (DRPs) like Pseudomonas aeruginosa and MRSA outside of specific locations.
- Variable Predictive Power: The predictive power of putative risk factors is highly variable, except for a prior culture of these pathogens.
- Overuse of Antibiotics: Global application of HCAP guidelines has not improved outcomes and has led to overuse of anti-MRSA and antipseudomonal antibiotics.
A Path Forward: Nuance and Local Data
The data suggests that physicians must understand the local epidemiology of CAP. Relying on published data from other sites may lead to undertreatment or overtreatment for antibiotic-resistant pathogens, each with potential adverse impacts. Molecular screening tests can identify presence, clinicians need to obtain sputum cultures to allow de-escalation if these pathogens are not present and document their local prevalence.
Clinicians should de-escalate therapy by discontinuing anti-MRSA and/or antipseudomonal coverage if cultures (or molecular testing) do not confirm these pathogens.
Like asking if wearing a thermal jacket is useful, asking if HCAP is useful depends on the circumstance. While appealing to have a simple rule for all situations, pneumonia is complex and cannot be distilled into a one-size-fits-all approach. Clinical skill and knowledge are still required to achieve the best outcomes.