Interpretive standards for disk susceptibility tests with Sch 21420 and amikacin

Abstract

Disk susceptibility tests with two structurally related aminoglycosides (amikacin and Sch 21420) were evaluated. Tests with 10-and 30-,ug amikacin disks confirmed previous recommendations for interpretive zone standards; 30-,ug disks are preferred. Tests with 10-, 20-, and 30-,ug Sch 21420 disks led to similar conclusions. The 30-,ug Sch 21420 disks are recommended, with zone standards of c14 mm for the resistant category (minimal inhibitory concentration, 232 ,Lg/ml) and 217 mm for the susceptible category (miniimal inhibitory concentration, -16

In-Vitro Efficacy of Synergistic Antibiotic Combinations in Multidrug Resistant Pseudomonas Aeruginosa Strains

“…Breakpoints for isepamycin were those recommended by Barry, et al4 and breakpoints for cefoperazone-sulbactam were those recommended by the manufacturer.…”

“…Disc diffusion test was performed, by using piperacillin (100 µg), ceftazidime (30 µg), piperacillin-tazobactam (100 + 10 µg), sulbactam/sefoperazon (30 + 75 µg), imipenem (10 µg), ciprofloxacin (5 µg), amikacin (30 µg), gentamicin (120 µg), netilmicin (30 µg), tobramicin (10 µg) (Oxoid, Hampshire, England) and isepamycin (30 µg) (Mast, Merseyside, England) discs, and the result was interpreted according to Clinical and Laboratory Standards Institute (CLSI) methodology. 2 , 3 Breakpoints for isepamycin were those recommended by Barry, et al 4 and breakpoints for cefoperazone-sulbactam were those recommended by the manufacturer.…”

“…The minimum inhibitory and bactericidal concentrations (MICs and MBCs) of ceftazidime, piperacillin/tazobactam, imipenem, ciprofloxacin, tobramycin and isepamycin were determined by broth microdilution method as described by CLSI, and CLSI criteria were used in the interpretations of the results. 4 , 5…”