Various lectins and sugars were used to study the possible role of saccharide-containing moieties on the surface of Candida albicans and human buccal cells in the adherence of this yeast to mucosal surfaces. The lectins possessed affinities for several different sugar moieties and were used to pretreat C. albicans or buccal cells before mixing and incubating in the adherence assay. It was found that concanavalin A, a lectin that recognizes mannose and glucose, inhibited adherence of the pretreated yeasts to buccal cells and also inhibited adherence of pretreated buccal cells to nonpretreated yeast cells. Adherence was restored by preincubating the concanavalin A with a mannose derivative, but preincubation of concanavalin A with other sugars did not produce this effect. Lectins that do not recognize mannose had no effect on adherence. The presence of alpha-D-methyl mannopyranoside in the incubation medium during the assay inhibited adherence, whereas other sugars did not. Germinated yeasts adhered to buccal cells more effectively than nongerminated cells and were more susceptible to adherence inhibition by concanavalin A than were nongerminated yeasts. Thus, mannose-containing moieties on the surface of C. albicans and buccal cells could mediate the adherence of this yeast to human epithelium.

The initial clearance of Candida albicans from the bloodstream of rats and from perfusion medium by perfused rat livers was characterized. Normal rats cleared over 90% of large doses of intravenously injected yeast cells in 5 min. All were recovered as viable cells among various reticuloendothelial organs after 30 min. The perfused rat liver trapped an average of 85% of the yeast cells in a single pass. No significant killing occurred, even in the presence of 10% whole rat blood. Scanning electron microscopy of cryofractured livers revealed that the cells were trapped in liver sinusoids but outside phagocytic cells. Bloodstream clearance of Candida albicans initially results in the accumulation of large numbers of yeast cells in the liver (2, 16). The primary objective of this study was to characterize the trapping by liver tissue within the first 30 min of exposure to the yeasts. Although it is generally thought that Kupffer cells account for most of the trapping and killing capacity of the liver (1-3, 7, 8, 10-12, 18-20, 23), Moon et al. (20) recently distinguished experimentally between the bactericidal and bacterial trapping functions by use of the isolated perfused liver. It was shown that the rate of bacterial trapping is essentially the same in the presence or absence of humoral factors and that Kupffer cells require humoral factors for killing to take place. We used a similar experimental approach to determine whether hepatic clearance and killing of C. albicans occurs in a manner analogous to that of bacteria. MATERIALS AND METHODS Animals. Sprague-Dawley-derived male rats weighing 300 to 400 g were purchased from Spartan Research Animals, Inc., Haslett, Mich. Animals were maintained under standard laboratory conditions with Purina laboratory chow and water available ad libitum. Cultivation of fungi. The strain of C. albicans used was isolated from a case ofcandidal vaginitis at the Olin Health Center of Michigan State University. Identity was confirmed by fermentation of glucose and maltose but not sucrose or lactose, chlamydospore production on 1% Tween 80 corn meal agar, and germ tube formation in 2 h at 37°C. Stock cultures were maintained on Sabouraud dextrose agar slants (Difco) at room temperature, and the inoculum was prepared as previously described (2). Standardization of the inoculum was made using ' Journal article no. 7740 from the Michigan Agricultural Experiment Station.

Spontaneous production of 5-fluorocytosine-resistant variants by three Candida albicans isolates is due to segregation from a preexisting heterozygous state.The fungistatic agent 5-fluorocytosine (5-FC) has repeatedly proven effective in the treatment of infections due to the pathogenic yeast Candida albicans (2, 3,7). This agent is relatively nontoxic to humans and is a desirable antifungal agent for that reason. However, resistant strains occur at significant frequency (1,8,14) and limit the clinical usefulness of 5-FC. Although the mechanism of action of 5-FC on C. albicans has been studied extensively (4,10,12,13), the genetic basis of resistance has not. Five genes determine 5-FC resistance in another yeast, Saccharomyces cerevisiae (6, 9).Recent biochemical and genetic studies indicate that typical C. albicans isolates are diploid (11,15,16). The genetic studies (15,16) showed, by induced mitotic segregation, that some clinical isolates are heterozygous for auxotrophic markers. The fact that 5-FC-resistant strains are common suggested to us that some or all C. albicans isolates might be heterozygous for 5-FC resistance and consequently capable of giving rise to resistant variants at high frequency by segregation. In the present report we show that some isolates give rise to resistant variants much more frequently than do other isolates and that three isolates of the former class are heterozygous for 5-FC resistance.Seventeen clinical isolates, previously described (15), were studied. All were sensitive to 5-FC: growth on a defined miniimal agar medium (MIN [5]) was inhibited by 5-FC at a clinically significant concentration (50 ,g/ml). In a standard experiment, approximately 105 cells (from culture on MIN agar) were spread on MFC50 agar (MIN plus 5-FC at 50 ,ug/ml), and the resultant cultures were examined for growth after incubation at 37°C. Five isolates, which we have designated type C, were strongly but incompletely inhibited by 5-FC; the majority of cells spread on MFC50 gave rise to microcolonies, and a minority of cells gave rise to larger colonies (Fig. 1

Tinea capitis remains a common infection among the pediatric population of North America. The 'gray patch' Microsporum audouinii infections of the 1950's have been supplanted by the 'black dot' ringworm of Trichophyton tonsurans. The clinical presentation of T. tonsurans infection is quite variable and may be related to specific host T-lymphocyte response. This dermatophytosis is most frequently incurred from contact with an infected child either directly or via a variety of fomites. Current studies indicate that an asymptomatic adult carrier state may also exist which could contribute to the morbidity of this mycosis.

Corynebacterium parvum vaccination significantly increased the number of leukocytes adherent to hepatic vessels. Perfused C. parvum-treated livers killed significantly more Candida albicans than did livers not treated with C. parvum, an effect reversed by the macrophage inhibitors silica, phenylbutazone, and iodoacetate.