Abstract
BackgroundThe causative pathogens of healthcare-associated pneumonia (HCAP) remain controversial, and the use of conventional cultivation of sputum samples is occasionally inappropriate due to the potential for oral bacterial contamination. It is also sometimes difficult to determine whether methicillin-resistant Staphylococcus aureus (MRSA) is a true causative pathogen of HCAP.MethodsWe evaluated the bacterial diversity in bronchoalveolar lavage fluid (BALF) using molecular and cultivation methods in 82 HCAP patients. BALF specimens were obtained from the lesions of pneumonia using bronchoscopy. The bacterial flora was analyzed according to the clone library method using amplified fragments of the 16S ribosomal RNA gene with universal primers. In addition, sputum cultures and the above specimens were assessed.ResultsEighty (97.6%) of the 82 BALF samples obtained from the patients with HCAP showed positive polymerase chain reaction results. The predominant phylotypes detected in the BALF in this study included bacteria common in cases of community- and hospital-acquired pneumonia. In addition, the phylotypes of streptococci and anaerobes were detected in 19 (23.2%) and 8 (9.8%) cases, respectively. In particular, phylotypes of streptococci were highly detected among the patients 75 of age or older. Staphylococcus aureus was cultured in 23 (28.0%) cases using conventional cultivation methods and detected in only 6 (7.3%) cases as predominant phylotypes according to the clone library method.ConclusionsThe clone library analysis of BALF in the HCAP patients detected heterogeneous bacteria and a high incidence of streptococci compared with that observed using cultivation methods. In addition, the results of our study may indicate a lower incidence of MRSA than previously expected in HCAP patients.
Highlights
Healthcare-associated pneumonia (HCAP) is a category of respiratory infection that was recently documented in the 2005 American Thoracic Society (ATS)/Infectious Diseases Society of America (IDSA) guidelines [1]
The clone library analysis of bronchoalveolar lavage fluid (BALF) in the HCAP patients detected heterogeneous bacteria and a high incidence of streptococci compared with that observed using cultivation methods
A total of 651 outpatients diagnosed with pneumonia were assessed for eligibility, and 82 HCAP patients who underwent bronchoscopic examinations were evaluated in this study (Fig 1)
Summary
Healthcare-associated pneumonia (HCAP) is a category of respiratory infection that was recently documented in the 2005 American Thoracic Society (ATS)/Infectious Diseases Society of America (IDSA) guidelines [1]. Recent reports have shown that 17.3–38.0% of patients with pneumonia can be categorized as having HCAP [3,4,5,6,7], and the number of patients with HCAP is expected to increase in association with the aging of the population [8]. Sputum examinations are widely used common methods for evaluating the causative pathogens of bacterial pneumonia. Due to unavoidable contamination with the upper respiratory tract, expectorated sputum samples are occasionally inadequate for identifying causative pathogens [9]. The causative pathogens of healthcare-associated pneumonia (HCAP) remain controversial, and the use of conventional cultivation of sputum samples is occasionally inappropriate due to the potential for oral bacterial contamination. It is sometimes difficult to determine whether methicillin-resistant Staphylococcus aureus (MRSA) is a true causative pathogen of HCAP.
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