Cost effectiveness of the antibiotic removal device for processing blood cultures

The antimicrobial removal device (ARD) blood culture system has been reported to increase the sensitivity of isolation of pathogenic microorganisms in bacteremic patients who are already on antibiotics. To determine the usefulness of this system to the clinician for the diagnosis of bacteremia and to determine the additional cost incurred by the use of the system, the microbiological results at two hospitals over a period of two years were compared. A total of 25,124 standard blood cultures (SBC) were performed with a positive culture rate of 10.7 percent. Of the 858 specimens processed by ARD alone, 68 (7.9 percent) were positive. There were a total of 2,657 specimens from 910 patients that were processed simultaneously using both systems. Both ARD and SBC were negative in 2,249 specimens, and 290 blood cultures from 107 patients grew the same organism using both systems. Thirty-one specimens from 12 patients grew pathogenic bacteria from ARD bottles; in each the SBC culture was negative. However, in 21 patients (44 specimens) bacteremia was detected only in SBC with negative cultures from ARD bottles.Thus, in the vast majority of the cases, SBC alone was sufficient to detect bacteremia, even in the patient with recent or concomitant antibiotic therapy. The total processing cost was calculated for the cases in which SBC and ARD were performed simultaneously and was found to be $6,588 for SBC and $15,005 for ARD. The comparative cost per bacteremic patient detected by the two methods was $46.40 for SBC and $555.75 for ARD.