Critical Care Medicine

Healthcare-Associated Pneumonia

Healthcare-associated pneumonia

Also known as: Nursing home pneumonia

Related conditions: Community-acquired pneumonia (CAP), hospital-acquired pneumonia

1. Description of the problem

Healthcare-associated pneumonia (HCAP) has emerged as a distinct syndrome. Though presenting 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 the following risk factors in a patient presenting from the community with a pneumonia: 1) Hospitalization for 2 days or more in the preceding 90 days; 2) Residence in a nursing home (NHR) or extended care facility; 3) Home infusion therapy (including antibiotics); 4) Chronic dialysis within 30 days; 5) Home wound care; and 6) Having a family member with multidrug-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.

Key management point

Rapid recognition of the risk for HCAP vs. CAP is critical.

2. Emergency Management

If the patient is hemodynamically compromised or exhibits signs of respiratory failure, stabilization of these life-threatening physiologic events should be undertaken as 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 24 hours of presentation is critical for optimizing outcomes. At the same time, studies show that patients presenting with HCAP are more likely than those with CAP to receive empiric treatment that does not cover the pathogen eventually identified in culture. This failure to cover the culprit organism adequately has been associated with both a 2- to 3-fold increase in the risk of hospital death, and an increase in hospital length of stay and attendant costs. Furthermore, broadening antibiotic coverage in response to a culture result does not mitigate the ill effects of inappropriate coverage within 24 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 needs to consider broadening antimicrobial coverage from that adequate for CAP to one recommended in the HCAP guideline.

Management point not to be missed

Whenever feasible, antibiotics should be administered after cultures have been obtained. Blood and sputum cultures are helpful at identifying the culprit organism.

3. Diagnosis

When a patient presents with pneumonia, the critical steps to identify HCAP vs. CAP are to ask about the list of the established risk factors that differentiate one from the other. As mentioned above, they are: 1) Hospitalization for 2 days or more in the preceding 90 days; 2) Residence in a nursing home (NHR) or extended care facility; 3) Home infusion therapy (including antibiotics); 4) Chronic dialysis within 30 days; 5) Home wound care; and 6) Having a family member with multidrug-resistant pathogen. If at least one of these criteria is present, the clinician needs to consider the possibility of a resistant pathogen and choose the empiric therapy accordingly. This risk stratification should take into account the local resistance patterns as well.

Normal lab values

As for any serious lower lung infection, the white cell count with a differential is helpful, and cultures of sputum and blood may aid in identifying the organism. A chest X-ray may confirm the presence of a pneumonia if an infiltrate is seen.

How do I know this is what the patient has?

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. Some investigators have attempted to sharpen the diagnostic definition of the risk for a resistant pathogen in the set of patients presenting 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.

Differential diagnosis

Although HCAP, due to its presentation from the community, is frequently confused with CAP, its unique epidemiology and microbiology require a different approach. Prior exposure to healthcare set the patient up for an increased risk of harboring a resistant pathogen.

Confirmatory tests

Blood culture, sputum culture and urinary antigen testing should be ordered prior to administering antibiotics.

4. Specific Treatment

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 β-lactam/ β-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 β-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.

5. Disease monitoring, follow-up and disposition

Expected response to treatment

Unadjusted hospital mortality for HCAP ranges from 10% to 25%, depending on the study, which is distinctly higher than for CAP. Initial inappropriate antimicrobial therapy has been shown to raise the risk of death roughly 2-fold, and escalation of treatment in response to culture data fails to attenuate this risk. In adjusted analyses HCAP raised mortality risk by 65% to 128% when compared to patients with CAP. Thus, in-hospital close monitoring for clinical improvement is warranted for HCAP patients. Because patients with HCAP tend to be older and have a higher chronic illness burden than those with CAP, close outpatient follow-up is indicated.

Incorrect diagnosis

The wrong diagnosis should be suspected if, despite adequate treatment, the patient either deteriorates or fails to exhibit adequate clinical improvement.

Follow-up

Because the patient is likely to be discharged on antibiotics, the follow-up should include not only confirmation of continued clinical improvement, but also 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 that the patient was discharged on with the view to eliminating any agents prescribed in the hospital that may be deemed potentially unnecessary in the recovering individual.

Pathophysiology

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

Epidemiology

HCAP is present in patients presenting with pneumonia generally from the community with several 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: 1) Hospitalization for 2 days or more in the preceding 90 days; 2) Residence in a nursing home (NHR) or extended care facility; 3) Home infusion therapy (including antibiotics); 4) Chronic dialysis within 30 days; 5) Home wound care; and 6) Having a family member with multidrug-resistant pathogen.

In multiple cohort studies, the proportion of all pneumonia patients hospitalized from the community represented by HCAP is between approximately 1/5 to 3/4 of the cohort, depending on the study. 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; yet this is consistently somewhat higher than for patients with CAP. Similarly, HCAP patients are older, have a higher comorbid disease burden, as well as a greater severity of acute illness than those presenting with CAP. Consequently, hospital mortality in HCAP is higher than in CAP, the adjusted analyses suggesting a 65% to 128% increase in this risk above the risk of hospital death in CAP.

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 rather 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 (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 vs. the CAP guideline. One important shortcoming of the study, which limits the interpretation of the results, is its lack of microbiology data, either as a culture-positive vs. culture-negative pneumonia or 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, which may be treated successfully with a CAP regimen despite HCAP risk factors. Alternatively, it is possible that the local patterns of resistance did not necessitate broad coverage.

Prognosis

N/A

Special considerations for nursing and allied health professionals.

N/A

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 looking 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

"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 is important in that it 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 is a very-well-done study for the first time describing 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. vol. 137. 2010. pp. 1130-7.

-- This very 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 perception and 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 successfully treated with CAP guideline-concordant therapy. Potentially confounding this observation is the fact that the investigators did not report culture data.
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