Rapid identification and antimicrobial susceptibility testing of pathogenic microorganisms from positive blood cultures

Abstract

Purpose Bloodstream infections (BSIs) are severe illnesses associated with high mortality. Delays in obtaining microbial culture results often hinder timely targeted antimicrobial therapy. Our study aimed to evaluate the feasibility of rapid pathogen identification (ID) and antimicrobial susceptibility testing (AST) in BSIs. Methods Positive blood culture (BC) broth was transferred into separation gel vacuum blood collection tubes for preprocessing, followed by pathogen identification via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Identification concordance rates (ICRs) were calculated against the conventional reference method. Bacterial membrane rapid AST (BMR-AST) and positive blood culture medium rapid AST (PBCMR-AST) were performed using cultured bacterial membrane and raw positive BC medium, respectively, with results compared to conventional method. Results A total of 210 specimens were analysed for rapid ID. ICRs were 74.6% (88/118) for Gram-negative bacteria (GNB), 37.2% (29/78) for Gram-positive bacteria (GPB), and 14.3% (2/14) for fungi. BMR-AST yielded category agreement (CA) >96% for 58 GNB (96.8%, 1125/1162) and 24 Gram-positive cocci (GPC, 97.7%, 334/342), with essential agreement (EA) above 97% for both groups. PBCMR-AST achieved 94.1% CA (270/287) among 65 Enterobacterales; overall CA reached 94.7% (557/588) across 70 GNB and 28 GPC for additional antimicrobials. Conclusion This rapid ID workflow performed well for GNB but suboptimally for GPB and fungi. Both rapid ASTs showed excellent concordance with the standard method for both GNB and GPC. These approaches can substantially shorten the turnaround time of positive BCs and hold promising clinical value for early BSI management.