Open AccessPaper Disk-Agar Diffusion Assay of Penicillin in the Presence of Streptomycin
Author(s) -
D Raahave
Publication year - 1974
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.6.5.603
Subject(s) - streptomycin , penicillin , chemistry , sarcina , agar , antibiotics , microbiology and biotechnology , agar diffusion test , bacteria , chromatography , biology , biochemistry , escherichia coli , gene , genetics
Microbiological assay of individual antibiotics in mixtures of antibiotics depends on the use of selective inactivation and/or of test bacteria with differential susceptibility. Controlled experiments revealed that streptomycin in concentrations of 20 and 40 μg/ml did not influence a disk diffusion assay of penicillin withSarcina lutea (ATCC 9341) as the test organism. In the case of penicillin concentrations less than or equal to 1 IU/ml, addition of 80 μg of streptomycin per ml influenced the penicillin assay significantly. Clinical use of streptomycin resulting in levels above 40 μg/ml usually did not occur; therefore penicillin could be assayed as though streptomycin were not present. We observed additionally thatS. lutea was unable to grow on agar plates prepared with semicarbazide hydrochloride.