Synergic activity of beta-lactamines and aminoglycosides vs. bacterial strains treated with sub-MIC concentrations.

ABSTRACT

The aim of the present paper was to evaluate the interaction between beta-lactamines and aminoglycosides against Gram-positive and Gram-negative bacteria previously treated with sub-inhibitory doses of each antibiotic in the combination. Bacterial strains were S. aureus ATTC 25923, S. mitis NCTC 3165, E. coli ATTC 25922, P. vulgaris ATTC 13315. Antibiotics used were penicillin G and gentamicin. The most synergistic combination was the ratio of 4 (penicillin G) to 1 (gentamicin) before and after sub-MIC treatment with penicillin.