Pneumonia was previously divided into three categories: community-acquired pneumonia, hospital-acquired (nosocomial) pneumonia, or ventilator-acquired pneumonia. These categories were useful because different organisms, diagnostic measures, and treatment options were associated with each type.
In the 1990s, it became apparent that other types of patients, such as those in nursing homes and dialysis centers, had a higher percentage of organisms more commonly associated with hospital-acquired pneumonia (HAP) and ventilator-acquired pneumonia (VAP) than with community-acquired pneumonia (CAP). Most antibiotic regimens for admitted CAP required a two-drug combination such as a third-generation cephalosporin and a macrolide. Empirically, in the ED, physicians began using more extended spectrum two-drug combinations for nursing home patients, and might have added vancomycin for dialysis patients.
In 2005, a highly influential study by Kollef (Chest 2005;128:3854) suggested that the bacteriology of pneumonia was essentially the same as HAP and VAP but not CAP in patients transferred from other health care facilities, in those on long-term hemodialysis, and in those hospitalized within 30 days. This study suggested a radical new approach to these patients, and was included in the guidelines for managing adults with HAP, VAP, and health care-associated pneumonia (HCAP). (Am J Respir Crit Care Med 2005;171:338.)
These guidelines expanded the definition of HCAP to include those who were hospitalized in an acute care facility for two or more days in the past 90 days, who reside in a nursing home or long-term care facility, who received IV antibiotics or chemotherapy, who had wound care in the past 30 days, who were on chronic dialysis, and who had a family member with multi-drug-resistant pathogen.
All these patients are presumed to be at risk for multi-drug resistant pathogens. Pneumonia was defined as the presence of new or progressive radiographic infiltrate with at least two of three clinical features: fever higher than 38°C, leukocytosis or leukopenia, and purulent respiratory secretions.
For those meeting the pneumonia definition, the diagnostic strategy states that “a lower respiratory tract culture needs to be collected from all patients before antibiotic therapy, but collection of cultures should not delay the initiation of therapy in critically ill patients.” (Am J Respir Crit Care Med 2005;171:338.) These deep specimens include an endotracheal aspirate, bronchoalveolar lavage, or protected brush specimens of the alveloi.
Treatment of patients with HCAP is the same for those with HAP or VAP. This includes antipseudomonal cephalosporin (ceftazidime, cefepime) or antipseudomonal carbapenem (imipenem or meropenem) or piperocillin-tazobactam plus antipsuedomonal fluoroquinolone (ciprofloxacin, levofloxacin) or aminoglycoside (amikacin, gentamicin, tobramycin) plus, if MRSA is suspected, linezolid or vancomycin.
There are many flaws in this new standard. Kollef based his work on a large database of patients who had pneumonia and positive lower respiratory cultures. (Chest 2005;128:3854.) Invasive procedures are required to obtain lower respiratory cultures. At my facility, we perform these procedures infrequently on pneumonia patients. Indications include VAP patients or patients failing to improve on conventional therapy. A database of patients with only positive lower respiratory cultures does not reflect the majority of the HCAP population, most of whom would not have had these procedures performed and many of whom would have had negative cultures.
A practical consideration is that the Centers for Medicare and Medicaid Services' core standards for pneumonia patients now include obtaining blood cultures for all admitted patients and administration of antibiotics within four hours of ED presentation. Most emergency departments added special resources to improve adherence to these standards. Performance of these invasive procedures within the four-hour antibiotic administration window is unrealistic.
Although the standards' various categories of HCAP patients, validation of categories has not occurred. It is estimated that 80 percent of all admitted pneumonia patients would fall into the HCAP, HAP, and VAP categories. (Eur J Clin Microbiol Infec Dis 2006;25:627.) This would impose enormous burdens on the health care system, such as requiring the admission of all patients from long-term care facilities.
Lastly, the recommendations treat all HCAP patients identically. We know, however, that the colonization bacteriology of different populations, such as nursing home and dialysis patients, is different, so we should tailor antibiotic treatment to the appropriate epidemiology of the organisms. There has been no prospective validation of any of the concepts proposed in these new guidelines. Here is a direct quote from the new standards:
“Although this document focuses more on HAP and VAP, most of the principles overlap with HCAP. Because most of the current data have been collected from patients with VAP and microbiological data from nonintubated patients may be les accurate, most of our information is derived from those with VAP, but by extrapolation can be applied to all patients with HAP.” (Am J Respir Crit Care Med 2005;171:338.)
These new standards impose enormous burdens on the emergency physician who must make rational decisions about which pneumonia patients to admit, what pre-antibiotic tests are required, and what are reasonable, cost-effective antibiotic regimens for empiric treatment. Validation of these categories of HCAP risks, organisms associated with HCAP risks, improved outcomes from the increase in hospitalizations, and the cost and number of antibiotics must be demonstrated. Just as “kids aren't just little adults,” “HCAP isn't just HAP or VAP.”
Listings of meetings in emergency medicine and related fields are now listed on Emergency Medicine News' web site, EM-News.com. To view the listings, click on Events Calendar.
To list a meeting in Emergency Medicine News and on the web site, send the name of the meeting, date, location, sponsor, and contact information, including a phone number to Emergency Medicine News, 333 Seventh Ave., 19th Fl., New York, NY 10001; [email protected].