Microecologyand Therapy MikroÓkologie und Thefapie vol. 25, 2'14-2'19 (1995) ISSN 0720-0536 Alpha-toxin is the maln haemolysin produced by Staphylo- coccus aureus st rains. The physico- chemical properties and biological activities of st ap h ylococcal alp ha- toxin have been a subject of very in- tensive research. This protein was found to be the most impońant factor of staphylococcalvirulence, showing a wide range of biological activities, mainly subsequentto its membrane- damagingaction.However, most of its MATERI ALS Alpha-toxin was obtained from S. aureus Wood 46 strain. Purification 2'7 4 Editedby Institut fiir Mikroókologie 35745 Herborn-Dill GermanY activities were shown in in vitro mod- els which may not fully reflect patho- physiological events taking place during infection. Moreover, the past studies have dealt with relativelycrude preparations, so some of the activities might have been modified due to im- purities.The aim of this study was to verify alpha-h aemolys in neurotoxic- ity - an issue of substantial contro- versy in t he past . AND METHODS was performed with the application of ion-exchange ch r om at og r ap h y f ol- I NFLUENCE OB STAPHYLOCOCCUS AUREUS ALPHA-TOXI N ON RABBI T BLOOD.BRAI N BARRI ER PERMEABI LI TY STEFAN TYSKI , ROMAN GADAMSKI , WALERI A HRYNI EWI CZ, and JAN ALBRECHT SUMMARY The aim of this study was to gst insight int o t he neurot oxicity of Staphylococcus aureus haemolysin - alpha-toxin. Purified staphy- lococcal alpha-toxin was injected into foot vein of Wistar rats. Evans blue and horse radish peroxidasestaining revealed no gen- eral blood-brainbarrier changesfor at least 24 hours, when a dose slightly below LD5O was applied. Morphometric analysis revealed an approximately 307o increaseof small vessel volume in cerebral cortex and hippocampus,associated with changes in erythrocytes shape, which were elongated in control rats, but round in alpha- toxin-treated animals. This ohenomenon was associatedwith de- creaseof erythrocyte surface. which in consequence could interfere with blood-brain t issue exchanse of met abolites. INTRODUCTION