[Serum antibacterial activity during antibiotic treatment in automated bacteriology]

The conventional serum-dilution bactericidal test used for monitoring antibiotic therapy in severely infected in patients requires 72 h. Use of an automaton would be expected to provide faster results. We tested the MS-2 diagnostic automaton which performs kinetic analysis of bacterial growth. A relation between exponential growth onset time and initial bacterial concentration of the inoculum was first determined using successive ratio 10 dilutions. Sixty-two serum samples from twenty-one patients with endocarditis or septicemia were examined. A selection of findings is presented. Results of the automatic method and serum-dilution bactericidal test are studied comparatively. From our data we define the major advantages of automation: only 0.65 ml of serum and 10 minutes are needed to perform the test and results are obtained in five to twelve hours according to the bacterial strain. This new technique could be integrated in the monitoring protocol of severe infections.