In Vivo pathogenicity of eight medically relevant Candida species in an animal model

Background: The relative pathogenicity of eight medically important Candida species was investigated in a mouse model. Materials and Methods: Seventeen isolates were included; two isolates of Candida albicans, Candida glabrata, Candida tropicalis, Candida lusitaniae, Candida parapsilosis, Candida kefyr and Candida guilliermondii and three Candida krusei isolates. Mice in groups of three or four were inoculated with 10(5) and 10(7) CFU, respectively. On days 2 and 7 kidneys were removed, weighed and CFU/g kidney determined by the spot technique. Results: Mortality was only observed in mice inoculated with C. albicans and C. tropicalis. Inoculated with 10(7) CFU C tropicalis, C glabrata, C kefyr C lusitaniae, C parapsilosis, C krusei and C guilliermondii the median Log CFU/g kidney was significantly different: 6.0, 6.0, 6.4, 7.0, 3.7, < 2 and < 2 respectively (p < 0.0001). Eye infection and histological changes of kidneys were examined for C. albicans, C. tropicalis, C glabrata and C krusei-infected mice. Weight Loss, kidney weight, inflammation and infection and number of eyes infected decreased with the pathogenicity of the four species. Conclusion: The virulence was highly different, illustrated by a 7-Log difference in CFU/g kidney, a span of 0-100% mortality and histological changes in kidneys ranging from discrete to serious. The species could be divided into three groups with decreasing virulence: 1) C. albicans and C tropicalis, 2) C glabrata, C. kefyr and C lusitaniae and 3) C parapsilosis, C krusei and C guilliermondii. To our knowledge this is the first study with a simultaneous comparison of all eight species in an immunocompetent animal model.