COMPARISON OF EFFICIENCY OF 3 METHODS FOR STERILITY TESTING OF OPHTHALMIC OINTMENTS CONTAINING ANTIBIOTICS

The efficiency of 3 methods for testing sterility of antibiotic ophthalmic ointments was compared. During storage of antibiotic ophthalmic ointments infected with bacteria some self-sterilization takes place mainly due to death of the antibiotic sensitive bacteria [Staphylococcus aureus, Escherichia coli, Bacillus subtilis and B. mycoides]. The results of determination of the ointment non-sterility depend on the level of bacterial loading, sensitivity of the cultures to the antibiotic and time of the culture contact with the antibiotic in the ointment before its testing. The method of ointment solution in isopropylmiristate and filtration through a membrane filter, followed by washing of the filter from the antibiotic and placing it into a thioglycol medium, was most effective for determination of bacterial admixtures in antibiotic ointments.