Adhesion and colonisation of Candida krusei on host surfaces

Abstract

Candida krusei is an emerging pathogen, especially in immunocompromised hosts. As the adherence of this organism both to host epithelial surfaces and to catheter and prosthetic surfaces appears to be important in the pathogenesis of superficial as well as systemic candidoses, the adhesion of 20 oral isolates of C. krusei and five oral isolates of C. albicans was compared with the following substrates: cultured (HeLa) epithelial cells, buccal epithelial cells (BEG) from healthy adults and bone marrow transplant patients, and acrylic (polymethylmethacrylate) surfaces. Animal experiments in Sprague Dawley rats were also conducted to evaluate the relative oral carriage rate of the two Candida spp. C. krusei isolates adhered in far greater numbers to acrylic surfaces than to either of the cell surfaces. Significant intra-species differences in C. krusei adhesion for acrylic surfaces were noted between 74 (39 %) of 190 pair comparisons in contrast to 18 (9.5 %) of 190 with HeLa surfaces (p < 0.05). A positive correlation was also observed between the adhesion of C. krusei isolates to HeLa cells and acrylic surfaces. Five isolates of C. albicans showed very low adherence to HeLa surfaces when compared with BEC obtained from either healthy individuals or bone marrow transplant patients. The adherence of C, albicans to BEC from the healthy individuals was c. 12-fold greater than that of C. krusei, a figure similar to the relative murine oral carriage rate of the two Candida spp. However, the adhesion of C. albicans to BEC from bone marrow transplant patients was three-fold less than to BEC of healthy individuals whilst C. krusei adhesion remained the same, reflecting a possible selective colonisation process which may operate in these patient groups, possibly as a result of drug therapy. The current data, while confirming the inter- and intra-species differences in adherence of Candida spp. to host surfaces, illustrate that adherence-related factors may operate during colonisation of C. krusei on mucosal, catheter and prosthetic surfaces, in vivo in both health and disease.