To evaluate the clinical application of fast identification of pathogens by two pretreatments of separation gel coagulation tube and sodium dodecyl sulfonate (SDS) on positive blood culture bottles with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

Positive blood samples in 120 aerobic bottles and 80 anaerobic bottles (confirmed single bacteria by Gram’s staining technique) were collected from November 2016 to May 2017 in microbiology laboratory of XuanwuHospital of Capital Medical University. The identification accuracy of the two methods was evaluated by comparing the pre-treatment of the separated gelatinizing tube and 0.5% SDS with the identification of MALDI-TOF MS in pure culture colonies.

The coincidence rates of identification with MALDI-TOF MS by the pretreatment of the separation gel coagulation tube method andthe SDS method were 86.0% and 87.0%, respectively. In the Separation Gel Coagulation tube method, the coincidences by aerobic bottle and anaerobic bottle were 86.7% and 85.0%, respectively, which were 85.0% and 90.0% for SDS method. No significant difference was identified in terms of coincidence with aerobic blood bottles for the two methods. However, the accuracy by SDS method was clearly superior to that of Separation Gel Coagulation tube method with anaerobic bottles (χ²= 11.14,P < 0.05). The accuracy rates for Gram-negative bacteria (94.3%, 94.3%) were significantly higher than those of Gram-positive bacteria (80.6%, 83.3%) andfungi(50.0%, 63.6%), with significant differences (χ²= 24.7, 40.3, 15.1; allP< 0.01). The two methods had no significant difference in accuracy of determining Gram-negative and Gram-positive bacteria. However, the identification accuracy offungiand anaerobic bacteria by SDS method was significantly higher than that of the separation gel coagulation tube method (χ²= 11.05,P< 0.01; χ²= 14.05,P < 0.05). The scores > 2.0 identified by pretreatment of separation gel and SDS method were 37.5% and 45.0% (χ²= 20.48, P< 0.05), which were 33.0% and 25.0% for scores 1.6-2.0 (χ²= 11.14,P< 0.05), and 15.5% and 17.0% for score < 1.6 (χ²= 5.9,P > 0.05).

The common pathogens in positive blood culture bottles can be quickly and directly identified by pretreatment of separation gel and SDS method, which significantly reduce the identification period. SDS method is better for identification offungiand anaerobes.