Clinical characteristics of patients with bacterial pleuritis in the presence of Streptococcus anginosus group and obligate anaerobes detected by clone library analysis.

Introduction: Bacterial pleuritis is one of the most important pleural and respiratory infectious diseases, in addition, there have been no reports describing the clinical characteristics of patients with bacterial pleuritis according to molecular methods. An accurate understanding of the clinical characteristics and etiology of bacterial pleuritis is an issue that must be addressed.

Objectives: The aim of this study was to clarify the clinical characteristics of the bacterial species in bacterial pleuritis.

Methods: Pleural effusion samples were obtained from 29 patients with bacterial pleuritis. The microbiota of pleural effusion samples was analyzed by clone library analysis using the 16S ribosomal RNA gene.

Results: The phylotypes of Fusobacterium spp. (24.1%) were most frequently the predominant phylotypes, followed by those of Streptococcus anginosus group (SAG) (20.7%) and S. aureus (17.2%). The predominant phylotypes of obligate anaerobes, including the Fusobacterium spp., were detected in 11 of 29 patients (37.9%). Patients in the SAG group were significantly older and presented lower serum albumin levels than those in the obligate anaerobe and other bacterial groups. Patients from the obligate anaerobe group took longer to present symptoms, and therefore the diagnosis of pleuritis was also delayed, in comparison to patients in the other bacterial groups.

Conclusions: Our results demonstrated that there were characteristic differences between patients in SAG, obligate anaerobe and other bacterial groups. Physicians may need to consider treatment strategy options based on the clinical characteristics of patients with bacterial pleuritis.