[In vitro combination effects of astromicin and beta-lactam antibiotics against Pseudomonas aeruginosa. In vitro synergistic activities].

In vitro synergistic activities of astromicin (ASTM), a new aminoglycoside antibiotic, combined with beta-lactam antibiotics (cefsulodin (CFS), cefoperazone (CPZ), latamoxef (LMOX) were investigated against P. aeruginosa by the checkerboard technique, FIC index and the killing curve. FIC indexes of ASTM in combination with beta-lactam antibiotics against 11 fresh clinical isolates of P. aeruginosa, P. aeruginosa BMH No. 1 and E-2 were synergistic or partially synergistic in most cases. Checkerboard of P. aeruginosa BMH No. 1 and E-2 to ASTM and 3 beta-lactam antibiotics showed the synergism, too. Bacteriostatic concentrations of ASTM, CFS, CPZ or LMOX showed synergistically bactericidal effects when these antibiotics were added in combination to the culture of P. aeruginosa BMH No. 1.