BACTERIOLOGICAL STUDIES ON THE COMBINEND ACTION OF AMINOGLYCOSIDE ANTIBIOTICS AND SYNTHETIC PENICILLINS AGAINST PSEUDOMONAS AERUGINOSA

Abstract

The synergic actions of SBPC, CBPC and GM, DKB were observed on either strain of Ps. Aeruginosa No. 12, Nc-5, IFO-3445 by chequer board titration method, and the marked effect was observed especially with No. 12 strain.
In either case of the combination of SBPC with GM, CBPC with GM, and CBPC with DKB, the simultaneous administration showed the highest bactericidal effect, followed by the case of addition of GM, DKB after adding SBPC, and the reverse case showed the similar effect to that of each drug alone.
The electron microscopic observation revealed that the bacterial cell prolonged with SBPC, CBPC, showing the filament-like form, and GM resulted in the crack of the cell-wall followed by the cytoplasmic membrane with the flowing out of the cellular contents.
In combination, the bacterial cell was prolonged but its degree was less than that by SBPC, CBPC alone, moreover, the damage at the surface layer of the cell was observed, while the degree of cellular damage was much severer than that by each drug alone.
The therapeutic experiment of infection demonstrated that the combination of SBPC with GM and CBPC with DKB showed superior effects than those of each drug alone.
While, in combination of SBPC with GM, more favorable effect was obtained by the simultaneous administration in 2 hours after infection.