Objective: Our study aimed to investigate the feasibility of pre-extraction with Tween 80 for blood culture bottles in which a sterile body fluid, excluding blood, was added and a positive signal was received.

Methods: In the present study, passages were taken from positive blood culture bottles inoculated with sterile body fluids onto the appropriate agar media. Bacterial identification was made with MALDI-TOF MS from bacterial colonies. In addition, pre-extraction with Tween 80 was applied to positive blood culture bottles.

Results: In the identification studies carried out after the pre-extraction process with Tween 80, success rates of 53.6% and 81.4% were obtained at species and genus levels, respectively. After the pre-extraction process, no statistically significant difference was observed at the genus level for gram-positive and gram-negative bacteria (p=0.808). This pretreatment provided more successful results at the species level, especially in gram-negative bacteria (p=0.021).

Conclusion: The pre-extraction process provided successful results for gram-negative bacteria. However, it showed limited activity at the species level for gram-positive bacteria. Developing new protocols using different concentrations of Tween 80 or other chemicals may be a useful way to increase the efficacy of gram-positive bacteria identification.