Oral Microbiol Immunol 2001: 16: 113–118 Copyright C Munksgaard 2001 Printed in Denmark . All rights reserved ISSN 0902-0055 J. Hannula 1 , B. Dogan 1,2 , J. Slots 3 , E. O ¨ kte 2 , S. Asikainen 1 Subgingival strains of Candida 1 Department of Periodontology, Institute of Dentistry, University of Helsinki, Helsinki, Finland, 2 Department of Periodontology, albicans in relation to geographical Faculty of Dentistry, University of Gazi, Ankara, Turkey, 3 Department of Periodontology, School of Dentistry, University of Southern California, Los origin and occurrence of Angeles, USA periodontal pathogenic bacteria Hannula J, Dogan B, Slots J, O ¨ kte E, Asikainen S. Subgingival strains of Candida albicans in relation to geographical origin and occurrence of periodontal pathogenic bacteria. Oral Microbiol Immunol 2001: 16: 113–118. C Munksgaard, 2001. Clonal diversity of subgingival yeast strains was determined in relation to geographical location and coexistence of selected periodontal pathogenic bacteria. A total of 60 dental patients from Finland, the United States and Turkey each contributed five Candida albicans isolates. C. albicans isolates were serotyped using slide agglutination and genotyped using polymerase chain reaction (PCR) amplification and a random sequence primer. In general, each study subject yielded Key words: subgingival; Candida albicans; C. albicans isolates belonging to the same serotype and genotype. C. albicans arbitrarily primed polymerase chain reaction; serotype A occurred more frequently in subjects from Finland and Turkey than in serotypes; geography; periodontal subjects from the United States. A total of 27 PCR-based C. albicans genotypes pathogenic bacteria were identified. One C. albicans genotype occurred with particularly high Johanna Hannula, Research Laboratory, frequency in subjects from Turkey and another genotype in subjects from the Institute of Dentistry, P.O. Box 41, FIN-00014 United States. Relationships were identified between C. albicans serotypes and University of Helsinki, Finland genotypes. Further studies are needed to determine environmental factors of importance for subgingival colonization and persistence of C. albicans. Accepted for publication August 21, 2000 Destructive periodontal diseases are caused mainly by gram-negative anaer- obic species (8). Approximately 20% of adult periodontitis patients also harbor subgingival yeasts (5, 25, 32, 33), most of which are members of the Candida albicans species (9, 26, 32). It is not known whether subgingival C. albicans participates in the pathogenesis of de- structive periodontal disease. Individuals may show varying affin- ity for oral colonization of C. albicans clones, and various geographical loca- tions may show predominance of differ- ent C. albicans clones (4, 16, 30). To date, most research has focused upon characterizing C. albicans strains from oral mucosal sites (4, 16, 30) and from nonoral body sites (4, 16, 30). Studies are needed to characterize periodontal C. albicans strains using modern mol- ecular techniques (4, 10, 16, 24, 30). Candida species are aerobic organ- isms that require neutral to acidic pH for optimal growth (22). Oral anaerobic (13) and intestinal anaerobic bacteria (14) inhibit colonization and replication of C. albicans, probably because an- aerobes grow at and produce low oxy- gen tension (18), negative oxidation-re- duction potential (15) and basic pH (7). Additionally, candidal growth depends upon availability of sugars, especially glucose (28), whereas most periodontal pathogenic bacteria are asaccharolytic and utilize glycoproteins, proteins and amino acids as nutrients, even though saccharolytic periodontally pathogenic species such as Prevotella intermedia and Actinobacillus actinomycetemcomit- ans also exist. Apparently, Candida and periodontal anaerobic bacteria differ considerably in ecological requirements and may not thrive in the same ecologi- cal niche for an extended period of time. The aim of this study was to deter- mine the relationship between C. al- bicans subtypes and geographical loca- tion and subgingival ecology, as as- sessed by the coexistence of various periodontally pathogenic bacteria. Material and methods C. albicans isolates Three hundred subgingival C. albicans isolates were obtained from the micro- biology laboratories at the Institute of Dentistry, University of Helsinki, Fin-