Evaluation of new blood culture processing systems.

The Antimicrobial Removal Device (ARD; Marion Scientific) was evaluated in vitro with simulated blood culture samples in fresh blood and clinically with samples from potentially septic patients to test its ability to remove antimicrobial agents and recover bacteria from blood culture specimens containing these drugs. In simulated specimens, the ARD was evaluated for adverse affects on microorganisms as well as compared with lysis-centrifugation (Isolator; Du Pont Co.), biphasic brain heart infusion bottles, and tryptic soy broth bottles for antimicrobial inactivation and organism recovery. There was no adverse effect of the ARD on organisms during a 4-h test period. The ARD was the only system to actually inactivate antimicrobial agents and removed greater than 99.2% of all antimicrobial agents tested from spiked and clinical specimens. Overall, with simulated blood culture specimens, the ARD recovered 90% of bacteria spiked into fresh blood containing antimicrobial agents, Isolator recovered 73%, biphasic brain heart infusion bottles recovered 31%, and tryptic soy broth bottles recovered 24%. In the clinical study, 43 of 86 clinically significant isolates were recovered only by ARD-assisted processing, 6 were recovered only by conventional processing, and 37 were recovered by both methods (the advantage of ARD processing over conventional processing in the clinical study was significant at P less than 0.001). Both clinical and simulated specimens demonstrated the ARD-associated blood culture processing to be the most efficient method for the isolation of microorganisms from specimens containing antimicrobial agents.