Subinhibitory concentrations of azoles are known to inhibit hyphal branchin
g of Candida albicans in liquid media. This study showed that subinhibitory
concentrations of fluconazole also inhibit agar invasion by C. albicans in
YPD solid medium. Agar invasion was markedly inhibited in two C. albicans
strains that were resistant to fluconazole. This suggests that the degree t
o which fluconazole inhibits agar invasion by C. albicans hyphae could serv
e as a marker of susceptibility to azoles.