Sensitivity of 523 blood culture isolates to 33 antibiotics

523 blood culture isolates collected during 18 months (July 1980-December 1981) were analysed by the agar dilution method for sensitivity to 33 antibiotics. Breakpoints corresponding to the SIR system were used but for N-formimidoyl-thienamycin (N-f-thienamycin), azthreonam and fosfomycin serial dilutions were made. Aminoglycosides (netilmicin, gentamicin, amikacin and tobramycin) inhibited from 90 to 86% of the strains. This was comparable to the percentage inhibited by some cephalosporins (cefotaxime, cefoperazone, ceftazidime, ceftriaxone, cefuroxime, cephamandole and moxalactam) ranging from 95 to 89%. A very high number of strains (99%) were inhibited by N-f-thienamycin. By combination of certain antibiotics more than 99% of the strains could be inhibited.