Pulmonary Medicine

Healthcare-associated Pneumonia

What every physician needs to know:

Healthcare-associated pneumonia (HCAP) has emerged as a distinct syndrome. Although it presents from the community, its unique epidemiology, microbiology, and outcomes attest to the influence of its victims' ongoing exposure to the healthcare system.

The 2005 guidelines from the American Thoracic Society and the Infectious Diseases Society of America define HCAP by the presence of at least one of six risk factors in a patient presenting from the community with a pneumonia:

1) Hospitalization for two or more days in the preceding ninety days

2) Residence in a nursing home (NHR) or extended care facility

3) Home infusion therapy (including antibiotics)

4) Chronic dialysis within thirty days

5) Home wound care

6) A family member with multi-drug-resistant pathogen.

Subsequent studies have variously added the presence of immune suppression and/or general need for home healthcare.

The purpose of inquiring about these risk factors is to identify patients at a higher risk for harboring an antibiotic-resistant pathogen since multiple studies have demonstrated that instituting appropriate empiric coverage can improve outcomes in HCAP. In a patient who presents from the community with symptoms, signs, and supportive data (white blood cell count, chest radiograph) of a pneumonia, the presence of any of the HCAP risk factors implies a higher probability of a resistant organism.

Classification:

Not applicable.

Are you sure your patient has healthcare-associated pneumonia? What should you expect to find?

HCAP is generally present in patients who present with pneumonia from the community with risk factors that underscore their continued encounters with the healthcare system. The following risk factors are put forth by the ATS/IDSA guidelines to define HCAP:

  • Hospitalization for two or more days in the preceding ninety days

  • Residence in a nursing home (NHR) or extended care facility

  • Home infusion therapy (including antibiotics)

  • Chronic dialysis within thirty days

  • Home wound care

  • A family member with multi-drug-resistant pathogen

Although MRSA and Pseudomonas are the most common pathogens in HCAP, the rates of culture positivity tend to be low, ranging from 1/3 to 2/3 of all HCAP patients; however, this rate is consistently higher than it is for patients with CAP. HCAP patients are also older and have a higher comorbid disease burden and greater severity of acute illness than those who present with CAP. Consequently, hospital mortality in HCAP is higher than it is in CAP; the adjusted analyses suggest a 65-128 percent increase in this risk above that in CAP.

Beware: there are other diseases that can mimic healthcare-associated pneumonia.

Although its presentation from the community results in HCAP's being frequently confused with community-acquired pneumonia (CAP), HCAP's unique epidemiology and microbiology require a different approach from that taken with CAP because prior exposure to healthcare sets the patient up for an increased risk of harboring a resistant pathogen.

In multiple cohort studies, the proportion of all pneumonia patients hospitalized from the community who have HCAP is 20-75 percent of the cohort, depending on the study.

How and/or why did the patient develop healthcare-associated pneumonia?

The pathophysiology is the same as for any pneumonic process, with the exception of the inciting organisms.

Which individuals are at greatest risk of developing healthcare-associated pneumonia?

When a patient presents with pneumonia, the critical step with which to identify HCAP vs. CAP are to ask about the list of six established risk factors that differentiate one from the other. If at least one of these criteria is present, the clinician should consider the possibility of a resistant pathogen and choose the empiric therapy accordingly. This risk stratification should also take into account the local resistance patterns.

Some investigators have attempted to sharpen the diagnostic definition of the risk for a resistant pathogen in patients who present with a pneumonia from the community. These attempts have resulted in a bedside scoring algorithm, where immune suppression, admission from a long-term care facility and a recent history of an exposure to antibiotics identified the risk of MRSA, Pseudomonas and extended-spectrum beta-lactamase organisms with greater accuracy than the HCAP definition did.

What laboratory studies should you order to help make the diagnosis, and how should you interpret the results?

Blood culture and urinary antigen testing should be ordered prior to administering antibiotics. It is recommended that a quantitative lower respiratory tract culture be obtained prior to instituting antibiotics if the patient's clinical condition allows. As for any serious infection, the white blood cell count with a differential is helpful.

What imaging studies will be helpful in making or excluding the diagnosis of healthcare-associated pneumonia?

A chest x-ray may confirm the presence of a pneumonia if an infiltrate is seen. In cases in which the clinical suspicion for pneumonia is high but the chest x-ray is normal, a chest CT may be helpful to demonstrate an infiltrate.

What non-invasive pulmonary diagnostic studies will be helpful in making or excluding the diagnosis of healthcare-associated pneumonia?

A chest x-ray to look for an infiltrate should be done upon admission. Laboratory data should include white blood cell count and blood cultures. The latter should be obtained prior to instituting antimicrobial coverage if the patient's clinical condition allows it.

What diagnostic procedures will be helpful in making or excluding the diagnosis of healthcare-associated pneumonia?

Chest x-ray, blood culture, and quantitative sputum culture (which can be obtained with tracheal suctioning or bronchoscopy) are helpful.

What pathology/cytology/genetic studies will be helpful in making or excluding the diagnosis of healthcare-associated pneumonia?

Not applicable.

If you decide the patient has healthcare-associated pneumonia, how should the patient be managed?

If the patient is hemodynamically compromised or exhibits signs of respiratory failure, stabilization of these life-threatening physiologic events should be undertaken per usual protocols.

The cornerstone of successful therapy in HCAP is tailoring empiric coverage for the most likely bacterial pathogen. Many studies indicate that adequate empiric antibiotic coverage within the first twenty-four hours of presentation is critical to optimize outcomes. At the same time, studies show that patients who present with HCAP are more likely than those with CAP to receive empiric treatment that does not cover the pathogen eventually identified in culture. The failure to cover the culprit organism adequately has been associated with a two- to three-fold increase in the risk of hospital death and an increase in length of hospital stay and attendant costs.

Broadening antibiotic coverage in response to a culture result does not mitigate the ill effects of inappropriate coverage within twenty-four hours of presentation.

Putting this evidence together makes a strong argument for adequate coverage up front. The intent of the HCAP definition is to alert the treating physician to the heightened possibility of an atypical pathogen, one with an increased probability of antimicrobial resistance. When a patient meets at least one of the HCAP criteria, the clinician should consider broadening antimicrobial coverage from that adequate for CAP to one recommended in the HCAP guideline.

Based on the risk factor profile, the ATS/IDSA guideline recommends that empiric treatment for a suspected HCAP include combination therapy with an antipseudomonal cephalosporin or a carbapenem or a beta-lactam/ beta-lactamase inhibitor plus an antipseudomonal fluoroquinolone or an aminoglycoside; linezolid or vancomycin should be added to this combination if the risk of methicillin-resistant Staphylococcus aureus (MRSA) is high. These antibiotic selections are distinctly broader than either a fluoroquinolone or a beta-lactam plus a macrolide, recommended for treatment of hospitalized patients with CAP. If these approaches prove ineffective, atypical pathogens or alternative diagnoses should be investigated.

Because the patient is likely to be discharged on antibiotics, the follow-up should include not only confirmation of continued clinical improvement, but also confirmation that there is no evidence of such potential complications as an antibiotic allergy or a secondary infection with Clostridium difficile. Follow-up should also include a review of the medications on which the patient was discharged with a view to eliminating any agents prescribed in the hospital that may be unnecessary in the recovering individual.

What is the prognosis for patients managed in the recommended ways?

Unadjusted hospital mortality for HCAP ranges from 10 percent to 25 percent, depending on the study, which is distinctly higher than the hospital mortality for CAP. Initial inappropriate antimicrobial therapy has been shown to roughly double the risk of death, and escalation of treatment in response to culture data fails to attenuate this risk. In adjusted analyses, HCAP raised mortality risk by 65-128 percent compared to patients with CAP. Therefore, close in-hospital monitoring for clinical improvement is warranted for HCAP patients. Because patients with HCAP tend to be older and to have a higher chronic illness burden than those with CAP do, close outpatient follow-up is indicated.

Although culture may be negative in many HCAP patients, at least one study suggests that, despite a higher prevalence of guideline-concordant treatment for CAP than HCAP among culture-negative HCAP patients (72% for culture-negative vs. 26% for culture-positive), unadjusted hospital mortality was significantly lower for those without a positive culture (7%) than in those with a positive culture (24.6%). One study in nursing home patients hospitalized for a pneumonia reported no significant differences in the clinical outcomes between patients treated according to the HCAP guideline vs. the CAP guideline.

One important shortcoming of the study that limits the interpretation of the results is its lack of microbiology data, either as a culture-positive vs. culture-negative pneumonia or as the actual pathogens isolated. It is possible that the lack of a difference in treatment was due to a high prevalence of culture-negative infections that, despite the presence of HCAP risk factors, may be treated successfully with a CAP regimen. It is also possible that the local patterns of resistance did not necessitate broad coverage.

What other considerations exist for patients with healthcare-associated pneumonia?

The patient's general status should be considered when making disposition decisions. Since HCAP patients tend to be more frail than those with CAP, they may require a period of rehabilitation following their acute illness. In addition, advanced directives discussion should be considered in appropriate cases.

What’s the evidence?

Kollef, MH, Shorr, A, Tabak, YP. "Epidemiology and outcomes of health-care-associated pneumonia: Results from a large US database of culture-positive pneumonia". Chest. vol. 128. 2005. pp. 3854-3862.

One of the defining HCAP cohort studies.

Micek, ST, Kollef, KE, Reichley, RM. "Health care-associated pneumonia and community-acquired pneumonia: a single-center experience". Antimicrob Agents Chemother. vol. 51. 2007. pp. 3568-73.

A detailed single-center cohort that looks at the outcomes of inappropriate initial treatment.

Morin, CA, Hadler, JL. "Population-based incidence and characteristics of community-onset Staphylococcus aureus infections with bacteremia in 4 metropolitan Connecticut areas, 1998". J Infect Dis. vol. 184. 2001. pp. 1029-34.

Seminal study of a healthcare-associated pathogen.

Friedman, ND, Kaye, KS, Stout, JE. "Health care-associated bloodstream infections in adults: A reason to change the accepted definition of community-acquired infections". Ann Intern Med. vol. 137. 2002. pp. 791-797.

Background for the HCA definition.

Siegman-Igra, Y, Fourer, B, Orni-Wasserlauf, R. "Reappraisal of community-acquired bacteremia: A proposal of a new classification for the spectrum of acquisition of bacteremia". Clin Infect Dis. vol. 34. 2002. pp. 1431-9.

Background for the HCA definition.

Shorr, AF, Tabak, YP, Killian, AD. "Healthcare-associated bloodstream infection: A distinct entity? Insights from a large US database". Crit Care Med. vol. 34. 2006. pp. 2588-95.

Background for the HCA definition.

McDonald, JR, Friedman, ND, Stout, JE. "Risk factors for ineffective therapy in patients with bloodstream infections". Arch Intern Med. vol. 165. 2005. pp. 308-313.

Background for the HCA definition.

"Hospital-acquired Pneumonia Guideline Committee of the American Thoracic Society and Infectious Diseases Society of America. Guidelines for the management of adults with hospital-acquired pneumonia, ventilator-associated pneumonia, and healthcare-associated pneumonia". Am J Respir Crit Care Med. vol. 171. 2005. pp. 388-416.

Evidence-based treatment guideline for VAP/HAP/HCAP; defines HCAP.

Mandell, LA, Wunderink, RG, Anzueto, A. "Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia". Clin Infect Dis. vol. 44. 2007. pp. S27-72.

Evidence-based CAP guideline.

Carratala, J, Mykietiuk, A, Fernandez-Sabe, N. "Health care-associated pneumonia requiring hospital admission: Epidemiology, antibiotic therapy and clinical outcomes". Arch Intern Med. vol. 167. 2007. pp. 1393-1399.

A Spanish cohort study of HCAP.

Shindo, Y, Sato, S, Maruyama, E. "Healthcare-associated pneumonia among hospitalized patients in a Japanese community hospital". Chest. vol. 135. 2009. pp. 633-40.

This is one of two important new cohort studies of HCAP vs. CAP epidemiology, microbiology and outcomes from Japan.

Venditti, M, Flacone, M, Corrao, S. "Outcomes of patients hospitalized with community-acquired, healthcare-associated and hospital-acquired pneumonia". Ann Intern Med. vol. 150. 2009. pp. 19-26.

This paper adds to our understanding of HCAP in Western Europe.

Schreiber, MP, Chan, CM, Shorr, AF. "Resistant pathogens in nonnosocomial pneumonia and respiratory failure: Is it time to refine the definition of health-care-associated pneumonia?". Chest. vol. 137. 2010. pp. 1283-8.

This study attempts to build a more accurate tool than the HCAP designation alone to stratify a pneumonia patient’s risk for harboring a resistant pathogen.

Seki, M, Hashiguchi, K, Tanaka, A. "Characteristics and disease severity of healthcare-associated pneumonia among patients in a hospital in Kitakyushu, Japan". J Infect Chemother. 2010 (Oct 8).

This is the second of two studies from Japan clarifying the differences between HCAP and CAP.

Park, HK, Song, JU, Um, SW. "Clinical characteristics of health care-associated pneumonia in a Korean teaching hospital". Respir Med. vol. 104. 2010. pp. 1729-35.

This well-done study is the first to describe the epidemiology of HCAP in Korea.

Iregui, M, Ward, S, Sherman, G. "Clinical importance of delays in the initiation of appropriate antibiotic treatment for ventilator-associated pneumonia". Chest. vol. 122. 2002. pp. 262-268.

Evidence on the impact of inappropriate empiric therapy.

Alvarez-Lerma, F. "Modification of empiric antibiotic treatment in patients with pneumonia acquired in the intensive care unit". Intensive Care Med. vol. 22. 1996. pp. 387-394.

Evidence on the impact of inappropriate empiric therapy.

Shorr, AF, Zilberberg, MD, Micek, ST, Kollef, MH. "Healthcare-associated pneumonia: A valuable concept at predicting resistant infections?". Arch Intern Med. vol. 168. 2008. pp. 2205-10.

Evidence that escalation in response to culture data does not reduce mortality risk in HCAP.

Labelle, AJ, Arnold, H, Reichley, RM, Micek, ST, Kollef, MH. "A comparison of culture-positive and culture-negative health-care-associated pneumonia". Chest. vol. 137. 2010. pp. 1130-7.

This important study suggests that, in contrast to culture-positive infection, culture-negative HCAP may be successfully treated with CAP guideline-concordant therapy.

Frei, CR, Attridge, RT, Mortensen, EM. "Guideline-concordant antibiotic use and survival among patients with community-acquired pneumonia admitted to the intensive care unit". Clin Ther. vol. 32. 2010. pp. 293-9.

Addresses guideline-concordant therapy and outcomes in CAP.

McCabe, C, Kirchner, C, Zahng, H, Daley, J, Fisman, DN. "Guideline-concordant therapy and reduced mortality and length of stay in adults with community-acquired pneumonia: Playing by the rules". Arch Intern Med. vol. 169. 2009. pp. 1525-31.

Addresses guideline-concordant therapy and outcomes in CAP.

Seymann, GB, Di Franceso, L, Sharpe, B. "The HCAP gap: differences between self-reported practice patterns and published guidelines for health care-associated pneumonia". Clin Infect Dis. vol. 49. 2009. pp. 1868-74.

Describes the gap between the perception and the reality of HCAP guideline-concordant treatment among MDs.

El-Solh, AA, Akinnusi, ME, Alfarah, Z, Patel, A. "Effect of antibiotic guidelines on outcomes of hospitalized patients with nursing home-acquired pneumonia". J Am Geriatr Soc. vol. 57. 2009. pp. 1030-5.

This study suggests that HCAP patients with nursing home-acquired pneumonia may be treated successfully with therapy in accordance with CAP guidelines. Potentially confounding this observation is the fact that the investigators did not report culture data.
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