Identification of micro-organism from positive blood cultures: comparison of three different short culturing methods...

Sepsis is one of the leading causes of death worldwide. The rapid identification (ID) of the causative micro-organisms is crucial for the patients' clinical outcome. MALDI-TOF MS has been widely investigated to speed up the time-to-report for ID from positive blood cultures, and many different procedures and protocols were developed, all of them attributable either to the direct separation of microbial cells from the blood cells, or to a short subculture approach. In this study, the Rapid Sepsityper workflow (MBT Sepsityper IVD Kit, Bruker Daltonics GmbH and Co. KG, Bremen, Germany) was compared to three different short subculturing methods, established into the routine practice of three different clinical microbiology laboratories. A total of N=503 routine samples were included in this study and tested in parallel with the two approaches. Results of the rapid procedures were finally compared to routine proceedings with Gram-staining and overnight subculture. Among monomicrobial samples, the Rapid Sepsityper workflow enabled overall the correct identification of 388/443 (87.6 %) micro-organisms, while the short subculturing methods of 267/435 (61.8 %). Except for the performance with Streptococcus pneumoniae, in each one of the three sites the Rapid Sepsityper workflow proved to be superior to the short subculture method, regardless of the protocol applied, and it delivered a result from 1 to 5 h earlier.