Disk diffusion sensitivity testing and antibacterial activity of azithromycin

Azithromycin (CAS 83905-01-5) disks with the selected loading (10, 15, 20 micrograms) were used for determination of the most suitable azithromycin disk concentration. Estimation was carried out by means of the regression line related to the zone size inhibition. Testing was performed on a variety of freshly isolated gram-positive, gram-negative and anaerobic bacteria derived from various specimens collected from patients. Using the disk diffusion method with 10 micrograms of azithromycin per disk in total 431 gram-positive, 875 gram-negative bacterial strains and 59 anaerobic bacteria were analysed. It was concluded that azithromycin disk containing 10 micrograms is sufficient for determination of bacterial sensitivity.