[Evaluation of three automated blood culture systems. Bio Argod, Bact T/Alert, bactec NR-860]

In 1991 and 1992, three automated blood culturing systems were successively assessed ("Diagnostics Pasteur" Bio Argos: 1,120 Vials, "Organon Teknika" BacT/Alert: 1,400 vials and "Becton Dickinson" bactec NR-860: 2,146 standard vials 6 and 7 and 2,360 resin vials 26 and 27), and compared with the conventional system (C) (Roche aerobic BHI-S Liquoîd, and Diagnostics Pasteur anaerobic prereduced Shaedler). Duplicate blood cultures were collected in various hospital services. They were processed over a 7-day period by the automated instruments and were incubated for 10 days using conventional techniques. The percentage of positivity (clinically significant results) obtained with the automated instruments was similar to that obtained with conventional techniques. Bio Argos: 3.4 p. cent vs 3.8 p. cent with C, BacT/Alert: 3.9 p. cent vs 3.5 p. cent, Bactec standard 6 and 7 vials: 5.6 p. cent vs 6.4 p. cent, and resin 26 and 27: 4.2 p. cent vs 3.1 p. cent. A better sensitivity was found with Bactec resin 26 and 27 vials when compared to C for Staphylococcus aureus (22 p. cent of S. aureus strains were isolated only with resin vials 26 and 27). False positives were as follow: 0.36 p. cent for BacT/Alert, 2.1 p. cent for Bio Argos and 3.5 p. cent for Bactec. The fastest detection rate was observed with the instrument which shakes the vials continuously (BacT/Alert): 73.6 p. cent of positive vials were detected on the day the vials were received at the laboratory. Ninety-four percent of the Bactec resin 26 and 27 positive vials, 90.6 p. cent of the BacT/Alert positive vials, 84 p. cent of the Bactec 6 and 7 positive vials and 73.7 p. cent of the Bio Argos positive vials were detected within twenty-four hours.