Significance of Anaerobes and Oral Bacteria in Community-Acquired Pneumonia

Abstract

BackgroundMolecular biological modalities with better detection rates have been applied to identify the bacteria causing infectious diseases. Approximately 10–48% of bacterial pathogens causing community-acquired pneumonia are not identified using conventional cultivation methods. This study evaluated the bacteriological causes of community-acquired pneumonia using a cultivation-independent clone library analysis of the 16S ribosomal RNA gene of bronchoalveolar lavage specimens, and compared the results with those of conventional cultivation methods.MethodsPatients with community-acquired pneumonia were enrolled based on their clinical and radiological findings. Bronchoalveolar lavage specimens were collected from pulmonary pathological lesions using bronchoscopy and evaluated by both a culture-independent molecular method and conventional cultivation methods. For the culture-independent molecular method, approximately 600 base pairs of 16S ribosomal RNA genes were amplified using polymerase chain reaction with universal primers, followed by the construction of clone libraries. The nucleotide sequences of 96 clones randomly chosen for each specimen were determined, and bacterial homology was searched. Conventional cultivation methods, including anaerobic cultures, were also performed using the same specimens.ResultsIn addition to known common pathogens of community-acquired pneumonia [Streptococcus pneumoniae (18.8%), Haemophilus influenzae (18.8%), Mycoplasma pneumoniae (17.2%)], molecular analysis of specimens from 64 patients with community-acquired pneumonia showed relatively higher rates of anaerobes (15.6%) and oral bacteria (15.6%) than previous reports.ConclusionOur findings suggest that anaerobes and oral bacteria are more frequently detected in patients with community-acquired pneumonia than previously believed. It is possible that these bacteria may play more important roles in community-acquired pneumonia.

Successful Additional Corticosteroid Treatment in a Patient with <i>Mycoplasm</i>a <i>pneumoniae</i> Pneumonia in whom a Monobacterial Infection was Confirmed by a Molecular Method Using Bronchoalveolar Lavage Fluid

“…In ad- M. pneumoniae infection is common in communityacquired pneumonia among young adults and children (1). Most patients infected with M. pneumoniae do not develop severe pneumonia.…”

“…The molecular method we used (1,20) can be used to identify pathogens that are generally difficult to cultivate using the ordinary cultivation methods, such as M. pneumoniae, and was identical for evaluating the bacterial flora in the sample. In general, complicated or refractory M. pneumoniae pneumonia tends to be considered to be a mixed infection of M. pneumoniae and other bacteria, therefore broad-spectrum antibiotics in addition to the agents effective for treating M. pneumoniae tend to be administered.…”

“…In the present patient, the molecular method using the BALF specimen revealed that the pneumonia of the present patient was due to a monobacterial infection of M. pneumoniae. In addition to the molecular analysis using the 16S rRNA gene, we used ethidium bromide staining to perform bacterial cell counting in the sample (1), and the total cell count of the specimen obtained from the BALF sample was 4.6×10 6 cells/mL. This number of bacterial cells was more than the median (2.6×10 6 cells/mL) of bacterial cell numbers in the BALF samples in patients with community-acquired pneumonia before starting antimicrobial treatment (1).…”

Dysphagia, dystussia, and aspiration pneumonia in elderly people

“…The main component of normal flora is basically oral streptococci, which are pathogenic for tooth decay (12). Recent genetic studies suggest that anaerobes and oral bacteria are detected in patients with community-acquired pneumonia more frequently than previously thought (14). These bacteria may play important roles in the development of aspiration pneumonia in the elderly.…”

“…These bacteria may play important roles in the development of aspiration pneumonia in the elderly. However, their prevalence is not so high, and bacterial pathogens are unclear in a large portion of aspiration pneumonia cases, suggesting the limited role of bacteria in aspiration pneumonia affecting the elderly (14,15).…”