IADR Abstract Archives
Growth and adherence patterns of clinical isolates of Candida albicans
Objectives: To determine the patterns of growth of clinical isolates of Candida albicans and their adherence to human ginigval fibroblasts.
Methods: Growth curves
Candida albicans isolates from stock were grown in Sabouraud Dextrose Broth (SDB) at 37oC on rotating plate for 18h. The cells were spun down, washed with PBS and resuspended in appropriate growth medium. 1x105 cells/ml of each Candida isolate was added to each of the various growth conditions (RPMI +/- 10%FBS, yeast nitrogen base (YNB), YNB + 25mM glucose, YNB + 50mM glucose, YNB + 100mM glucose). The reactions were carried out in 96-well plates and optical densities (OD) read at 520nm over a 24 hour period.
Yeast cell adherence assay
Gingival fibroblast monolayer was grown to confluence in 6-well cell culture plates. 1x107 of each Candida strain was inoculated into each well using PBS as a control. After incubation for one hour at 37°C, the cell monolayer with Candida attached was washed with PBS. The monolayer was detached, the supernatants serially diluted onto Sabouraud agar plates and incubated at 37°C for 24 hours. Results were reported as cfu/ml.
Results: Growth curves in vitro showed that a cutaneous isolate (3630) and a reference strain (SC5314) initiated germ tube formation at about 9 hours, whereas proliferation of an oral isolate (3683) was delayed until 11 hours. Despite this, 3630 and 3683 showed similar ability to adhere to gingival fibroblasts compared to a reference strain (SC5314) (see table 1and figure 2), that was significantly more virulent after i.v. infection, but was less able to establish oral infections in mice. It was noted that SC5314 demonstrated more extensive filamentation than either 3630 and 3683 (see figure 1), which may have accounted for differences in susceptibility to oral and i.v. infection.
Conclusions: These preliminary results have revealed signifcant differences in growth and adherence that may influence therapeutic considerations in patients with oral candidiasis. Future comparisons with additional clinical isolates will provide further evidence for these hypotheses.
Methods: Growth curves
Candida albicans isolates from stock were grown in Sabouraud Dextrose Broth (SDB) at 37oC on rotating plate for 18h. The cells were spun down, washed with PBS and resuspended in appropriate growth medium. 1x105 cells/ml of each Candida isolate was added to each of the various growth conditions (RPMI +/- 10%FBS, yeast nitrogen base (YNB), YNB + 25mM glucose, YNB + 50mM glucose, YNB + 100mM glucose). The reactions were carried out in 96-well plates and optical densities (OD) read at 520nm over a 24 hour period.
Yeast cell adherence assay
Gingival fibroblast monolayer was grown to confluence in 6-well cell culture plates. 1x107 of each Candida strain was inoculated into each well using PBS as a control. After incubation for one hour at 37°C, the cell monolayer with Candida attached was washed with PBS. The monolayer was detached, the supernatants serially diluted onto Sabouraud agar plates and incubated at 37°C for 24 hours. Results were reported as cfu/ml.
Results: Growth curves in vitro showed that a cutaneous isolate (3630) and a reference strain (SC5314) initiated germ tube formation at about 9 hours, whereas proliferation of an oral isolate (3683) was delayed until 11 hours. Despite this, 3630 and 3683 showed similar ability to adhere to gingival fibroblasts compared to a reference strain (SC5314) (see table 1and figure 2), that was significantly more virulent after i.v. infection, but was less able to establish oral infections in mice. It was noted that SC5314 demonstrated more extensive filamentation than either 3630 and 3683 (see figure 1), which may have accounted for differences in susceptibility to oral and i.v. infection.
Conclusions: These preliminary results have revealed signifcant differences in growth and adherence that may influence therapeutic considerations in patients with oral candidiasis. Future comparisons with additional clinical isolates will provide further evidence for these hypotheses.
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