[Antibacterial spectrum of mezlocillin and MIC/disc correlations (author's transl)]

Mezlocillin is a semi-synthetic antibiotic belonging to the ureidopenicillin group. A study of its activity against a wide range of organisms shows that it is a broad-spectrum antibiotic. However, mezlocillin differs from aminopenicillins and carbenicillin by its activity against numerous strains of klebsiella spp. (modal MIC 4 micrograms/ml). It is also slightly more active than carbenicillin against Pseudomonas spp. (modal MIC 16 micrograms/ml). The regression line relating MICs and disc zone diameters was calculated by the least square method. The correlation coefficient was 0.85.