Abstract:

Objectives To explore the feasibility of rapid identification and drug sensitivity test by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDI-TOF MS） after enrichment of bacteria in cerebrospinal fluid（CSF） culture with blood culture bottle. Methods A total of 1 446 CSF samples from Huashan Hospital affiliated to Fudan University from December 2018 to July 2019 were collected. Of them,345 samples were randomly cultured by blood culture bottle enrichment method,and the other 1 101 samples were cultured by conventional enrichment method. The positive rate of 2 groups were compared. The positive samples of blood culture bottle enrichment method were identified by MALDI-TOF MS and carried out drug sensitivity experiment using the rapid method（BD gel was used to separate serum tubes and enrich bacteria）and conventional method（transfer overnight to obtain pure bacteria）. The coincidence rate of identification and in vitro drug sensitivity test were analyzed. Results Compared with the routine culture,the positive rate of CSF blood culture bottle enrichment method increased significantly（χ²=60.889,P=0.000）. In 48 positive samples of CSF blood culture bottle enrichment method,the coincidence rate of rapid method and routine method was 89.80%,and there was no statistical significance between the 2 methods（χ²=0.116,P=0.990）. In the comparison of rapid and routine in vitro drug sensitivity experiment,for Gram-negative bacteria,except tigacycline with microdilution broth method had a low classification consistency,the consistent rates of other methods and antibacterial drugs were 100%;the consistent rates of erythromycin with Kirby-Bauer method,erythromycin and gentamycin with microdilution broth method,and clindamycin and gentamycin with instrument method were slightly poor,but the consistent rates of other antibacterial drugs were 100%. The consistent rates of classification and standard of cryptococcus rapid drug sensitivity were 100%. Based on pure bacteriummicrodilution broth method,the standard consistent rates of rapid microdilution broth method and rapid instrument method were 98.56% and 97.83%,respectively. Conclusions The positive rate of CSF blood culture bottle enrichment method and the detection rate of refractory bacteria can be improved without prolonging the time of positive report. The rapid identification and drug sensitivity experiment of direct centrifugation by using BD gels can greatly shorten the clinical report time and provide a rapid and accurate basis for clinical medication.

Key words: Cerebrospinal fluid, Blood culture bottle enrichment method, Rapid identification, Rapid drug sensitivity experiment