Flore bactérienne des exacerbations aiguës de bronchopneumopathie chronique obstructive (BPCO) à Kunming, Chine

[Bacteriology of acute exacerbations of chronic obstructive pulmonary disease in Tunisia]

INTRODUCTION

The role of bacteria, including atypical organisms, in acute exacerbations of chronic obstructive pulmonary disease (AECOPD) has been assessed in various ways in Tunisia.

METHODS

This was a descriptive and analytical study of patients with a mean age of 68.3±10.5 years hospitalized for AECOPD. Bacteriological examination included a cytological sputum exam and serology for atypical organisms including Mycoplasma pneumoniae, Coxiella burnetii, Chlamydophila pneumoniae and Legionella pneumophila using standard techniques.

RESULTS

Of the 240 patients enrolled, 175 sputum cultures (73%) were considered significant. Twenty-nine cultures were positive (16.5%) and 31 microorganisms were isolated of which the most frequent were P. aeruginosa (25.8%), K. pneumoniae (16.2%), H. influenzae (13%) and S. pneumoniae (9.7%). The prevalence of C. pneumoniae, M. pneumoniae and C. burnetii was 8.4%, 9% and 6.6%, respectively. No L. pneumophila infection was found. The Anthonisen criteria were associated with a positive culture (P=0.04). Almost half (40.9%) of the isolates were resistant to conventional first line antibiotics (43.7% to amoxicillin-clavulanic acid).

CONCLUSIONS

Awareness of the low positivity of quantitative sputum bacteriology and the large percentage of resistant strains with a predominance of exclusively multi-resistant Pseudomonas should help in the management of patients with AECOPD.

16S rDNA-based metagenomic analysis of dental plaque and lung bacteria in patients with severe acute exacerbations of chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVE

Acute exacerbations of chronic obstructive pulmonary disease (AE-COPD) are leading causes of mortality in hospital intensive care units. We sought to determine whether dental plaque biofilms might harbor pathogenic bacteria that can eventually cause lung infections in patients with severe AE-COPD.

MATERIAL AND METHODS

Paired samples of subgingival plaque biofilm and tracheal aspirate were collected from 53 patients with severe AE-COPD. Total bacterial DNA was extracted from each sample individually for polymerase chain reaction amplification and/or generation of bacterial 16S rDNA sequences and cDNA libraries. We used a metagenomic approach, based on bacterial 16S rDNA sequences, to compare the distribution of species present in dental plaque and lung.

RESULTS

Analysis of 1060 sequences (20 clones per patient) revealed a wide range of aerobic, anaerobic, pathogenic, opportunistic, novel and uncultivable bacterial species. Species indistinguishable between the paired subgingival plaque and tracheal aspirate samples (97-100% similarity in 16S rDNA sequence) were dental plaque pathogens (Aggregatibacter actinomycetemcomitans, Capnocytophaga sputigena, Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola) and lung pathogens (Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa and Streptococcus pneumoniae). Real-time polymerase chain reaction of 16S rDNA indicated lower levels of Pseudomonas aeruginosa and Porphyromonas gingivalis colonizing the dental plaques compared with the paired tracheal aspirate samples.

CONCLUSION

These results support the hypothesis that dental bacteria may contribute to the pathology of severe AE-COPD.