Impact of rapid identification of positive blood cultures by Verigene system on antibiotic prescription: prospective study of community-onset bacteremia in a tertiary hospital in Japan

Background: Rapid identification of positive blood cultures is important for the rapid initiation of optimal treatment of septic patients and enhancing antimicrobial stewardship programs (ASP). The utility of automated, microarray-based rapid identification systems has been reported; however, its effect on antibiotic prescription against community-onset bacteremia (COB) remains unclear.

Methods: We prospectively enrolled 185 episodes of COB in 177 patients between August 2014 and December 2015. Episodes of bacteremia due to Gram-positive bacteria (GP) and Gram-negative bacteria (GN) in the same patient were counted separately. COB was defined as bacteremia occurring within 72 h of admission. For GP bacteremia, only patients with ≥ 2 sets of positive blood cultures were included to exclude contamination episode. The primary study objective was to evaluate the rates of antibiotic prescription change within 24 h of rapid identification by Verigene system. Antibiotic prescription changes included switching to other antibiotics and discontinuation of antibiotics initially started.

Results: The median age of the subjects was 72 years (IQR: 62–82) and 103 (58%) were male. Bacteremia due to GN included 144 (78%) episodes, and GP included 41 (22%) episodes. Antibiotic prescriptions changes within 24 h were 52 (28%) after the Verigene test and 67 (36%) after conventional identification. Prescription changes after Verigene identification were more frequent in GP (17 [42%]) than in GN (35 [24%]) (p = 0.048); however, the rates were similar between GP and GN after conventional identification (15 [37%], 52 [36%], respectively). Bacterial identification agreement between the 2 tests was high (GP: 40/41[98%], GN: 142/144 [99%]). The Verigene test correctly predicted all antimicrobial resistance (mecA: MRSA [2/2], MRSE [1/1], CTX-M: ESBL E. coli [13/13], ESBL K. pneumoniae [1/1]). Hours from the initiation of incubation and reporting of the results of the Verigene system and conventional method were 28.3 h (IQR: 25.8–43.4) and 90.6 h (68.3–118.4), respectively.

Conclusion: In a community-onset bacteremia population, we observed a high rate of antibiotic prescription changes after the Verigene test, which was more prominent in GP than GN. The Verigene system is a strong asset for ASP in this population.