Health-Care-Associated Pneumonia Is Primarily Due to Aspiration Pneumonia

Abstract

To the Editor: In a recent issue of CHEST (March 2009), Shindo and coworkers1Shindo Y Sato S Maruyama E et al.Health-care-associated pneumonia among hospitalized patients in a Japanese community hospital.Chest. 2009; 135: 633-640Abstract Full Text Full Text PDF PubMed Scopus (222) Google Scholar reported the clinical features of health-care-associated pneumonia (HCAP) and the mortality rate among patients hospitalized with HCAP in Japan. They found that a therapeutic strategy for patients with moderate HCAP holds the key to reducing mortality. Physicians may need to consider potentially drug-resistant (PDR) pathogens when selecting the initial empirical antibiotic treatment for HCAP. We completely agree with the authors that the occurrence of PDR pathogens is associated with an unsuccessful initial treatment and inappropriate initial antibiotic treatment. However, the origin of PDR pathogens and the mechanisms underlying HCAP were not fully described in their article. Because the average life span of individuals has rapidly increased in developed countries, most of the hospitalized patients with pneumonia are older patients, who are likely to aspirate oropharyngeal contents during the night without witness.2Teramoto S Yamamoto H Yamaguchi Y et al.Lower respiratory tract infection outcomes are predicted better by an age > 80 years than by CURB-65.Eur Respir J. 2008; 31: 477-478Crossref PubMed Scopus (12) Google Scholar, 3Teramoto S Fukuchi Y Sasaki H et al.High incidence of aspiration pneumonia in community- and hospital-acquired pneumonia in hospitalized patients: a multicenter, prospective study in Japan.J Am Geriatr Soc. 2008; 56: 577-579Crossref PubMed Scopus (302) Google Scholar In a previous study,3Teramoto S Fukuchi Y Sasaki H et al.High incidence of aspiration pneumonia in community- and hospital-acquired pneumonia in hospitalized patients: a multicenter, prospective study in Japan.J Am Geriatr Soc. 2008; 56: 577-579Crossref PubMed Scopus (302) Google Scholar we conducted a swallowing function test and reported a very high incidence of aspiration pneumonia among hospitalized patients with pneumonia, including community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP). The criteria for the diagnosis of HCAP are consistent with the features of aspiration pneumonia. We found that patients with a history of hospitalization of ≥ 2 days in the preceding 90 days and a stay at a nursing home or extended care facility had a high risk for aspiration pneumonia. In fact, the data collected by the authors indicated that the patients with HCAP are older than those with CAP (mean age, 81.3 years vs 69.7 years, respectively). Gram-negative pathogens and streptococci other than Streptococcus pneumoniae, Pseudomonas aeruginosa, and methicillin-resistant Streptococcus aureus were isolated more frequently in HCAP patients than in CAP patients. Silent aspiration is extremely common in the elderly patients, and aspiration during the night is the primary cause of pneumonia in the elderly. Oropharyngeal materials contain Gram-negative pathogens and streptococci, which are aspirated into the lower airways of patients with dysphagia. Hence, the severity of pneumonia and the occurrence of PDR pathogens were considerably affected by swallowing dysfunction rather than the locations where pneumonia had occurred. Aspiration pneumonia frequently recurs, and it is initially diagnosed as CAP. However, within the next 90 days of hospitalization, the condition should be diagnosed as HCAP. If not, it leads to poor prognosis of HCAP and a higher number of PDR pathogens in patients with HCAP. Hence, the initial treatment of HCAP should be similar to that for HAP and ventilator-associated pneumonia.4Kollef MH Health-care-associated pneumonia: not just a US phenomenon.Chest. 2009; 135: 633-640Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar The Japanese guidelines for the management of pneumonia recommend a therapeutic strategy for aspiration pneumonia that is very similar to that for the management of ventilator-associated pneumonia or HAP. It is important to bear this in mind for elucidating a preventive strategy for HCAP. Because aspiration pneumonia is predominant in patients with HCAP, swallowing rehabilitation and oral care may prove to be very effective in reducing the incidence of HCAP in the future.5Teramoto S Ishii T Yamamoto H et al.Significance of chronic cough as a defence mechanism or a symptom in elderly patients with aspiration and aspiration pneumonia.Eur Respir J. 2005; 25: 210-211Crossref PubMed Scopus (10) Google Scholar, 6Teramoto S Yamamoto H Yamaguchi Y et al.A novel diagnostic test for the risk of aspiration pneumonia in the elderly.Chest. 2004; 125: 801-802Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar The evidence of the effectiveness of therapeutic modalities for aspiration pneumonia may be applicable for a majority of the HCAP patients. Health-Care-Associated Pneumonia Is Primarily Due to Aspiration Pneumonia: ResponseCHESTVol. 136Issue 6PreviewTo the Editor: Full-Text PDF