MALDI-TOF MS, following separation gel coagulation tubes and short-term solid phase culture effectively detects...

This study explored the viability of combining separation gel coagulation tubes with a short-term solid-phase culture method and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) for the detection of pathogens in positive blood culture bottles.

Positive blood culture bottles (186) were collected from the Affiliated Hospital of Putian University. The blood culture bottles were processed using separation gel coagulation tubes to isolate plasma components. After centrifugation, the solid phase containing microbial cells was subjected to a 4-6 h short-term solid-phase culture. Bacterial identification was subsequently done using MALDI-TOF MS.

The genus and species identification coincidence rates for 107 Gram-negative bacteria were 90.7 % (97/107) and 86.0 % (92/107), respectively, and 73.7 % (56/76) and 72.4 % (55/76), respectively, for 76 Gram-positive bacteria. For the 37 isolates that were either identified only to the genus level or not identified, the coincidence rates of MALDI-TOF MS after 4 and 6 h of short-term solid-phase culture were 32.4 % (12/37) and 86.5 % (32/37), respectively.

The combination of separation gel coagulation tubes, short-term solid-phase culture, and MALDI-TOF MS is fast and effective for identifying positive blood culture bottles in routine testing in clinical microbiology laboratories. Gram-negative bacteria are accurately and quickly identified compared to Gram-positive bacteria.