Effects of tetracycline hydrochloride and chlorhexidine gluconate on Candida albicans. An in vitro study

This study examined the effects of tetracycline hydrochloride (TCN) and chlorhexidine gluconate (CHX) on the growth and viability of Candida albicans. Subcultures of Candida albicans on Sabouraud's agar, were divided into 5 treatment groups: group 1, untreated control; group 2, 0.12% CHX; group 3, 3.0 mg/ml TCN adjusted to pH 4.5; groups 4 and 5, sodium azide free Tris buffer adjusted to pH 4.5 and pH 7.4, respectively. All groups were incubated for 10 days, and sampled and subcultured daily to determine the viability of each group. Additional samples from group 2 (day 4), group 4 (day 7) and all groups at day 10 were selected for SEM and TEM examination. Visual, SEM and TEM results showed that for groups 1, 3, 4, and 5 there was a heavy and constant uniform growth of Candida albicans throughout the period of the study. However, group 2 (CHX), showed decreasing viability and attachment from day 3 to day 10, with SEM and TEM revealing decreased blastospores and profound changes in the ultrastructural morphology, indicating inhibition of normal cell growth and replication. These results show that TCN even when used at high concentrations, in vitro, will allow uninhibited growth of Candida albicans whereas CHX inhibits cell growth and replication.