EN
The standard, non lysogenic, bacteriophage free S. aureus NTCC 8325-4 strain was lysogenized willi 15 different, obtained in our laboratory staphylokinase-converting bacteriophage belonging to serological groups A, B and F. MIC and MBC of vancomycin as well as the ratio of MBC to MIC were evaluated for all 15 lysogenic derivatives. The obtained results were compared with those for maternal strain. In the case of eight strains the ratio MBC/MIC showed the presence of tolerance to vankomycin (MBC/MIC ≥ 32). Four of the vancomycin-tolerant derivatives were lysogenized with bacteriophages belonging to the serological group A, two wen members of group B and two belonged to group F.