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Healthcare-associated pneumonia

In medicine, healthcare-associated pneumonia (HCAP) is a novel category of pneumonia in patients with recent close contact with the health care system.

HCAP is a condition in patients who are not hospitalised (similar to community-acquired pneumonia, CAP) but its causes, prognosis, prevention and treatment are more similar to hospital-acquired pneumonia (HAP). The category was introduced because healthcare has increasingly shifted from hospital-based to home care, and more people are residing in nursing homes or extended care facilities. Nursing home-acquired pneumonia is an important subgroup of HCAP. Residents of long term care facilities may become infected through their contacts with the healthcare system; as such, the microbes responsible for their pneumonias may be different from those traditionally seen in community-dwelling patients, requiring therapy with different antibiotics. Other groups include patients who admitted as a day case for regular hemodialysis or intravenous infusion (for example, chemotherapy).

Especially in the very old and in demented patients, HCAP is likely to present with atypical symptoms. Compared to subjects with CAP, the pneumonia in HCAP is more likely to be caused by bacteria resistant to first line antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa. The optimal antibiotic strategy for the treatment of HCAP remains controversial. Influenza vaccines have been shown to reduce the risk of pneumonia in nursing home residents. The pneumococcal polysaccharide vaccine is also recommended, although the evidence for its preventative role against pneumonia is more conflicting.

Definition

Healthcare-associated pneumonia can be defined as pneumonia in a patient with at least one of the following risk factors:

hospitalization in an acute care hospital for two or more days in the last 90 days;
residence in a nursing home or long-term care facility in the last 90 days
receiving outpatient intravenous therapy (like antibiotics or chemotherapy) within the past 30 days
receiving home wound care within the past 30 days
attending a hospital clinic or dialysis center in the last 30 days
having a family member with known multi-drug resistant pathogens

Although patients with HCAP may have more severe disease than those with classic CAP, disease severity does not determine if a patient has HCAP or not; the label HCAP is merely an indicator of risk factors for multi-drug resistant bacteria.

Epidemiology

Several studies found that healthcare-associated pneumonia is the second most common type of pneumonia, occurring less commonly than community-acquired pneumonia but more frequently than hospital-acquired pneumonia and ventilator-associated pneumonia. Patients with HCAP are older and more commonly have simultaneous health problems (such as previous stroke, heart failure and diabetes).

The number of residents in long term care facilities is expected to rise dramatically over the next 30 years. These older adults are known to develop pneumonia 10 times more than their community-dwelling peers, and hospital admittance rates are 30 times higher.

Causes

The bacteria found in patients with HCAP are more similar to HAP than to CAP; compared to CAP, they have higher rates of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa, and less Streptococcus pneumoniae and Haemophilus influenzae. It is well known that nursing home residents have high rates of colonization with MRSA. However, not all studies have found high rates of S. aureus and gram-negative bacteria. One factor responsible for these differences is the reliance on sputum samples and the strictness of the criteria to discriminate between colonising or disease-causing bacteria. Moreover, sputum samples might be less frequently obtained in the elderly.

Aspiration (both of microscopic drops and macroscopic amounts of nose and throat secretions) is thought to be the most important cause of HCAP. Dental plaque might also be a reservoir for bacteria in HCAP.

Prognosis

Healthcare-associated pneumonia seems to have fatality rates similar to hospital-acquired pneumonia, worse than community-acquired pneumonia but less severe than pneumonia in ventilated patients. Besides clinical markers like tachypnea (fast breathing) or a high white cell count (leukocytosis), the prognosis seems to be influenced by the underlying associated diseases (comorbidities) and functional capacities (for example, the ADL score). Many patients have a decreased health condition after the episode.

Treatment

Patients with HCAP are more likely than those with community-acquired pneumonia to receive inappropriate antibiotics that do not target the bacteria causing their disease.

In 2002, an expert panel made recommendations about the evaluation and treatment of probable nursing home-acquired pneumonia. They defined probably pneumonia, emphasized expedite antibiotic treatment (which is known to improve survival) and drafted criteria for the hospitalization of willing patients.

For initial treatment in the nursing home, a fluoroquinolone antibiotic suitable for respiratory infections (moxifloxacin, for example), or amoxicillin with clavulanic acid plus a macrolide has been suggested. In a hospital setting, injected (parenteral) fluoroquinolones or a second- or third-generation cephalosporin plus a macrolide could be used. Other factors that need to be taken into account are recent antibiotic therapy (because of possible resistance caused by recent exposure), known carrier state or risk factors for resistant organisms (for example, known carrier of MRSA or presence of bronchiectasis predisposing to Pseudomonas aeruginosa), or suspicion of possible Legionella pneumophila infection (legionnaires disease).

In 2005, the American Thoracic Society and Infectious Diseases Society of America have published guidelines suggesting antibiotics specifically for HCAP. The guidelines recommend combination therapy with an agent from each of the following groups to cover for both Pseudomonas aeruginosa and MRSA. This is based on studies using sputum samples and intensive care patients, in whom these bacteria were commonly found.

cefepime, ceftazidime, imipenem, meropenem or piperacillin–tazobactam; plus
ciprofloxacin, levofloxacin, amikacin, gentamicin, or tobramycin; plus
Linezolid or vancomycin

Guidelines from Canada suggest that HCAP can be treated like community-acquired pneumonia with antibiotics targeting Streptococcus pneumoniae, based on studies using blood cultures in different settings which have not found high rates of MRSA or Pseudomonas.

Besides prompt antibiotic treatment, supportive measure for organ failure (such as cardiac decompensation) are also important. Another consideration goes to hospital referral; although more severe pneumonia requires admission to an acute care facility, this also predisposes to hazards of hospitalization such as delirium, urinary incontinence, depression, falls, restraint use, functional decline, adverse drug effects and hospital infections. Therefore, mild pneumonia might be better dealt with inside the long term care facility. In patients with a limited life expectancy (for example, those with advanced dementia), end-of-life pneumonia also requires recognition and appropriate, palliative care.