Plotting regression lines for a new beta-lactam antibiotic (mecillinam).

Regression lines for mecillinam (FL 1060) were established according to the recommendations of th ICS. The investigation involved 477 Gram-negative and Gram-positive organisms with the widest possible spectrum of sensitivity which were isolated from fresh material for examination. Solid and liquid Müller-Hinton media (Merck and BBL) were used as nutrient media. The Difco Müller-Hinton medium is not suitable for this subtance because of the high ionic content. A general regression line for mecillinam is not admissible. The considerably restricted sphere of indication shown by our studies is presented with reference to the blood levels attainable in vivo. At the same time, the good sensivity of salmonella is pointed out.