Subclinical infections of cardiac implantable electronic devices: insights into the host-bacteria dialog from blood and pocket tissue with pyrosequencing.

While bacteria exist in CIED patients without clinical signs of infection, the underlying bacterial community structure and diversity in the bloodstream and pocket tissue of asymptomatic CIED patients remain unknown. In this study, we performed high-throughput 454 pyrosequencing of bacterial 16S rDNA of blood and pocket tissue from 54 asymptomatic CIED patients as well as blood from 30 normal individuals (normal controls). Firstly, we observed a significant increase of blood bacterial diversity in patients as compared with blood of normal subjects or patient tissues. We also found significant differences in 13 blood-associated bacterial genera between patients and normal subjects, and 14 bacteria genera between blood and tissues within patients. Secondly, we found that the serum levels of four inflammatory markers (CRP, IL-1β, IL-6, and MCP-1) in CIED patients were significantly higher than those in normal subjects. Thirdly, we found that there were significant correlations between 43 bacterial species and these inflammatory markers. Taken together, our results reveal a high diversity in the microbial community in CIED patients, and suggest the potential roles of multiple bacteria co-occurrence in the CIED subclinical infections.