[Multi-center evaluation of Showa disk susceptibility to presumptively determine minimum inhibitory concentrations through linear regression analysis].

To confirm the reliability of minimum inhibitory concentrations (MICs) determined by use of predefined linear regressions to bacterial growth inhibitory zone diameter on Showa disk susceptibility test, the multi-center evaluation along daily routines was performed in comparison with the standard agar dilution method. In total, 4,107 (89.0%) of 4,613 testings gave comparable MICs with 4-fold or less differences to those determined by the standard agar dilutions. The agreement of MICs (less than or equal to 4-fold differences) for gram-negative rods, excluding Pseudomonas aeruginosa, against 10 antimicrobial agents was estimated to 92.1%, and those for gram-positive cocci against 9 agents and for the strains of Pseudomonas aeruginosa against 8 agents were 84.5% and 81.7%, respectively. With these results, we can conclude that, under the well-controlled test procedures, the MIC correlates determined by Showa disk susceptibility test are enough comparable to those determined by the standard agar dilution method.