Background: Bloodstream infection (BSI) is a severe complication in immunocompromised patients. Prompt identification of causative microorganisms would improve the outcome of BSI due to optimization of antimicrobial treatment. Next-generation sequencing (NGS) allows us to analyze comprehensively and quantitatively all microorganisms present in a clinical sample in comparison with blood culture. However, there are currently no established methods to identify causative pathogens by NGS.
Methods: BSI was defined by the following criteria: 1) pathogen isolated from blood culture and 2) fever ≥38.0 Celsius or C-reactive protein >1.0 mg/dL. Thirty-five pediatric patients (12 with BSI and 23 with suspected BSI/negative blood culture) were enrolled. Plasma/serum samples were used for sequencing and the results were compared with those from blood culture. The bacterial reads per million reads of the sequence depth (BR) and relative importance values of the dominant bacteria (P1) were applied to identify causative pathogens.
Results: Sequencing reads of bacteria isolated in blood culture were identified by NGS in all plasma/serum samples at the onset of BSI. Additionally, bacteria isolated in blood culture were identical to the dominant bacteria by NGS in 8 of 12 patients with BSI. Causative microorganisms were detected when the NGS results fulfilled the criteria of BR >200 and P1 >0.5. In two patients with catheter-related BSI, causative bacteria were detected in the plasma/serum at 7 days before disease onset. Causative pathogens (Tatlockia micdadei, Escherichia coli, and human adenovirus 2) were identified in three of 23 patients in the suspected BSI group. A total of 62 resistance genes were detected in nine patients with sequences covering 5-100% of references.
Conclusion: An NGS-based approach has great potential for analysis of causative microorganisms in BSI and may help to diagnose a disease before disease onset. Antimicrobial resistance genes can also be found through sequence data processing.
Y. Okuno, None
N. Tetsuka, None
T. Suzuki, None
S. Ando, None
Y. Kamiya, None
Y. Torii, None
T. Yagi, None
Y. Takahashi, None
Y. Ito, None
See more of: Oral Abstract Session