In addition, the old definition treated each of these groups as having equal risk for all MDRs, when research seems to suggest that the risk for patients having a MRSA infection vs an MDR pseudomonal infection is actually quite different. Not surprisingly, treatment with broad-spectrum antibiotics for patients meeting the criteria for HCAP failed to show significant benefit (with the limitation that most of these studies are retrospective) and resulted in increased, potentially inappropriate use of these drugs, further contributing to antibiotic resistance.1

That said, there is another, more parochial use of the concept — such as when it is written in a patient’s chart — that likely still conveys valuable information. My suspicion is that when most practitioners write HCAP in a patient’s chart they are not thinking about the original definition. Rather, this is really shorthand for what the new ATS/IDSA guidelines suggest as the replacement for the original concept of “healthcare-associated pneumonia,” which is an assessment of the local resistance patterns at your institution. For example, knowing that the patient from the local outpatient dialysis unit likely is colonized with MRSA and that the resident from a skilled-nursing facility with chronic obstructive pulmonary disease likely is colonized with pseudomonas.

In this narrow setting, the concept of thinking of the local healthcare environment and the risk of resistant bacterial pneumonia still likely has value, and if that is easily conveyed to your fellow practitioners with the abbreviation of HCAP, it seems reasonable to use it.

Pulmonology Advisor: If you do agree that the term should no longer be used, what might be more useful ways to identify and treat these patients?

Dr Bartley: The following markers and strategies are recommended.

Individual characteristics of each patient for MRSA, extended-spectrum β-lactamase-producing enterobacteria including but not limited to Klebsiella pneumoniae and P aeruginosa:

  • Review of prior microbiology information for the specific patient, especially prior respiratory cultures
  • Use of MRSA polymerase chair reaction testing of the nares for early de-escalation of vancomycin or anti-MRSA agents
  • Obtain respiratory cultures and blood cultures for patients suspected of having Paeruginosa and MDR enterobacteria
  • Know your local regional CAP microbiology
  • Individualize antibiotics for your hospital. For example, are you treating patients with significant immunosuppression, who are receiving chemotherapy, who have had a transplant, have AIDS, are chronically ill, or reside in a nursing home? 
  • The ATS/IDSA CAP guidelines recommend empiric coverage of MRSA or Pseudomonas using local validated risk factors for either pathogen, and if empiric cover without local etiologic data is used, it is recommended to obtain cultures for early de-escalation within 48 hours.1,3,5 

Dr Exline: Clinicians need to be familiar with their local resistance patterns and antibiogram. They need to be familiar with the differences in resistance patterns based on the patient source (eg, home, skilled nursing facility, outlying hospital), the location of the patient in the hospital, the infection site, and the type of bacteria. For example, in our intensive care unit, the resistance pattern of our local pseudomonal strains is markedly different when the infected site is the lung (high risk of MDRs) vs a bloodstream infection, in which the isolates are usually pansensitive.

Pulmonology Advisor: Should hospitals and providers develop better protocols to evaluate local and regional pathogens?

Dr Bartley: Yes. The use of MRSA of the nares is sufficient for de-escalation of high negative predictive value but not for continuation of MRSA coverage, due to poor positive predicted value.1 If results are positive, specific actions including blood and sputum cultures should be performed:

  • Stewardship program to act early on microbiology results
  • Early de-escalation within 48 hours based on clinical response
  • Local antibiograms
  • Cultures respiratory/blood in cases of severe pneumonia
  • Cultures respiratory/blood in special populations at high risk for MDR organisms, transplant, bronchiectasis, severe chronic obstructive pulmonary disease with frequent antibiotics and/or admissions, highly immunosuppressed patients
  • Culture patient with no response to initial therapy5

Knowing the risk of MRSA bacteremia, intravenous drug users, central lines, prosthetic epidemiology is important, as is the understanding that in some cases the initial syndrome that appears to be pneumonia actually reflects embolic MRSA bacteremia.

Dr Exline: Hospitals should absolutely be looking to have better protocols to identify the local antimicrobial environment and should share their data with their community partners to ensure that patterns of resistance can be better understood. For smaller institutions that lack the infrastructure of a full epidemiology department, partnering with other community institutions may be helpful.

Pulmonology Advisor: What are the remaining needs pertaining to this topic in terms of research or education?

Dr Bartley: Additional research is needed to characterize S aureus pneumonia, as clinical and regular radiographic studies do not easily discriminate between respiratory colonization and a true infection. There is also a need for additional research and education regarding microbiology for specific groups, as well as more involved stewardship to facilitate early 24- to 48-hour re-evaluation of antibiotic therapy, de-escalation of antibiotics if there is clinical improvement, and establishing a total duration of antibiotics from 5 to 7 days for pneumonia.

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Dr Exline: No change in definition can replace the need for good antimicrobial stewardship. Clinicians need to think about the risk factors for each individual patient, including the risks for resistant bacteria and the severity of illness. For some of us, computerized decision support using algorithms in our electronic medical records to identify the risks for antimicrobial resistance may be helpful and easier to use than previous scoring systems that were difficult to implement in real time.

We have to be willing to re-evaluate our antimicrobial choices daily and narrow and shorten antibiotic courses as we gain more clinical information. I personally have found that using procalcitonin to determine cessation of antibiotics has been helpful when I am on the fence about stopping antibiotics.

References

1. Ewig S, Kolditz M, Pletz MW, Chalmers J. Healthcare-associated pneumonia: is there any reason to continue to utilize this label in 2019? Clin Microbiol Infect. 2019;25(10):1173-1179.

2. American Thoracic Society; Infectious Diseases Society of America. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005;171(4):388-416.

3. Kett DH, Cano E, Quartin AA, et al; on behalf of the Improving Medicine through Pathway Assessment of Critical Therapy of Hospital-Acquired Pneumonia (IMPACT-HAP) Investigators. Implementation of guidelines for management of possible multidrug-resistant pneumonia in intensive care: an observational, multicentre cohort study. Lancet Infect Dis. 2011;11(3):181-189.

4. Kalil AC, Metersky ML, Klompas M, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016;63(5):e61-e111.

5. 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 Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45-e67.