DETECTION OF CANDIDA-ALBICANS DNA WITH A YEAST-SPECIFIC PRIMER SYSTEMBY POLYMERASE CHAIN-REACTION

The in vitro and in vivo selectivity and sensitivity of a yeast-specif ic primer system was investigated. A two-step polymerase chain reactio n (PCR) was used: the first amplified a 245-bp fragment of the gene fo r cytochrome P450L(1)A(1) and the second a product of 193 bp. This nes ted PCR produced an approximately 1000-fold increase in the sensitivit y of the test for Candida albicans DNA compared with the first primer pair. The lower level of sensitivity of the test in physiological sali ne and tissue homogenate was about 10 C. albicans cells ml(-1). On the other hand, the sensitivity of the nested PCR method was reduced by a factor of more than 1000 when C. albicans was fixed with 4% formalin. After i.v. injection of different doses of C. albicans into mice, the yeast could be demonstrated in blood and in six different organs. The nested PCR was to some extent more sensitive than culturing for the d etection of the yeast in the specimens of organs such as lung, cardiac muscle, liver, kidneys and brain. In contrast, in blood and spleen th e culture was superior to the PCR technique used. Nested PCR is thus a useful additional method for the demonstration of yeasts.