APPLICATION OF A MODIFIED DISC DIFFUSION TECHNIQUE TO ANTIMICROBIAL SUSCEPTIBILITY TESTING OF VIBRIO-ANGUILLARUM AND AEROMONAS-SALMONICIDA CLINICAL ISOLATES

Two techniques for antimicrobial susceptibility testing of Vibrio angu illarum and Aeromonas salmonicida strains were compared. The first met hod was the reference test that determines Minimal Inhibitory Concentr ations (MIG); the second was a modified diffusion test that measures t he Inhibitory Concentrations in Diffusion (ICD) by carrying out the di ffusion test with five discs of differing contents, ICD measurement wa s not applicable for the susceptibility testing of oxytetracycline and sulfadimethoxine. On the other hand, a good correlation between the M ICs and the ICDs was observed for oxolinic acid, sarafloxacin, chloram phenicol and trimethoprim. Moreover, the ICD values were close to thos e obtained for the MIC values. A. salmonicida resistant strains were d etected by ICD determination. Thus, ICD could be used instead of MIC f or oxolinic acid, sarafloxacin, trimethoprim and chloramphenicol susce ptibility testings. The ICD technique is easy to carry out and is not dependent on the growth characteristics of bacteria.