[Semi-quantitative determination of resistance in agar (author's transl)]

The sensitivity of microorganisms to antimicrobial preparations is determined--using agar as the test medium--by means of a semi-quantitative method involving two concentrations, i.e. a low concentration relating to serum levels easily attained at the commonly used dosage level of the various antibacterially acting preparations, and a high concentration corresponding to serum levels attainable at increased dosage via the appropriate route of administration. The inoculum is distributed with a multi-inoculator making a simultaneous inoculation of 25 strains possible. For 25 antibiograms with 20 antibiotics 40 Petri dishes are required, inoculation take 15 min. The method described is suited above all for laboratories with large workload where a great number of resistance determinations must be carried out rapidly, precisely at a low cost.