SummaryMedically important yeasts of the genus Candida secrete aspartyl proteinases (Sap), which are of particular interest as virulence factors. Six closely related gene sequences, SAP1 to SAP6, for secreted proteinases are present in Candida albicans. The methylotrophic yeast Pichia pastoris was chosen as an expression system for preparing substantial amounts of each Sap isoenzyme. Interestingly, Sap4, Sap5 and Sap6, which have not yet been detected in C. albicans cultures in vitro, were produced as active recombinant enzymes. Different Sap polyclonal antibodies were raised in rabbits and tested before further application by enzyme-linked immunosorbent assay (ELISA) against each recombinant Sap. Two antisera recognized only Sap4 to Sap6. Using these antisera, together with sap null mutants obtained by targeted mutagenesis, we could demonstrate a high production of Sap4, Sap5 and Sap6 by C. albicans cells after phagocytosis by murine peritoneal macrophages. Furthermore, a ⌬sap4,5,6 null mutant was killed 53% more effectively after contact with macrophages than the wild-type strain. These results support a role for Sap4 to Sap6 in pathogenicity.

The results are of clinical relevance. In comparison with the mean bacterial counts of the untreated samples, all irradiation programs studied in this investigation reduced mean bacterial colonization in a biofilm on intraoral rough titanium surfaces by more than 98%. The actual extent of reduction was dependent on the bacteria species as well as on the irradiation mode.

The aim of the in vitro study was to evaluate the decontamination potential of common antiseptic solutions for heat-sensitive implantological drill guide templates. One hundred implantologists were evaluated on the basis of a questionnaire for their measures of disinfection. On the basis of these results, 80% alcohol, Octenidine 0.1%, and Chlorhexidine 0.12% were tested in an in vitro model for their decontamination efficacy for heat-sensitive plastic material infected with Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, Enterobacter cloacae, Escherichia coli, and Candida albicans. The microorganisms were selected on the basis of results of environmental testing of dental laboratories. The results of the questionnaire revealed that Chlorhexidine was used by 30%, 80% alcohol by 23%, and Octenidine by 7% of the dentists. Using the in vitro model, with the exception of S. aureus, Chlorhexidine was not able to completely eliminate the microorganisms after 15 min of application. In contrast, the treatment with Octenidine revealed no further growth of the tested microorganisms after that time. The 80% alcohol was more efficient. No growth of microorganisms could be detected in any of the tests after 5 min of incubation. On the basis of our results and due to the fact that suitable installations for sterilization were hardly used by the dental practitioners, the disinfection of templates should be preferentially performed with 80% alcohol or Octenidine using an incubation time of 15 min with ultrasonication.

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