[Serum bactericidal rate. Methodological proposal to predict the efficacy of antimicrobial therapy]

Several in vitro techniques have been developed, which are able to quantify the bactericidal activity of a determined antibacterial drug against an infective agent. The Serum Bactericidal Rate (SBR) is proposed as a complementary technique for the determination of the "killing curve", the serum bactericidal test or the minimal bactericidal concentration. SBR takes into account the most advantageous features of both of them. SBR is based on quantifying at different times the survival of the bacterial inoculum exposed to the patient's serum. Thus, bactericide speed is evaluated in the first hours of contact with the microorganism (as in the "killing curve"), but taking into account drug concentrations which have been reached by the patient (as in the serum bactericidal test). Preliminary assays suggest that SBR may have greater capacity to discriminate an infectious agent in answer to different therapeutic schemes than other determinations, although prospective studies are required to evaluate its predictive value.