Bacteriocinogenic properties of Staphylococci isolated from the oral cavity

Two hundred ninety two staphylococcal strains were isolated out of 130 saliva samples taken from children and adults, among which 116 were coagulase-positive and 176 coagulase negative. Bacteriocinogenic activity against Staphylococcus aureus strain Oxford 209P was found in 13 (4.5%) of the strains only. On the other hand, when a set of 15 sensitive staphylococcal strains selected by cross checking was used for the study 260 (89.0%) strains were found to be bacteriocinogenic. It was found that a higher percentage of coagulase-positive staphylococcal strains is sensitive to staphylococcins than of coagulase-negative strains. However, mean zone of inhibition is smaller in the case of former than of the latter strains. It was shown, that in the case of active strains a positive correlation exists between a percentage of coagulase-positive and negative strains inhibited by them and also between a percentage of all inhibited strains and a mean diameter if the growth inhibition zone. Simultaneous occurrence in saliva of two or more staphylococcal strains was found in 106 persons examined. In 93.4% of those cases coexisting strains did not show antagonistic properties: in remaining 6.6% despite of the number of simultaneously existing strains in oral cavity only one strain showed antagonistic properties against the remaining strains.