Nosocomial Candida. Epidemiology, transmission, and prevention

Antifungal activity of LY303366, a novel echinocandin B, in experimental disseminated candidiasis in rabbits

The safety and antifungal activity of LY303366 (LY), a new broad-spectrum semisynthetic echinocandin, were studied against disseminated candidiasis in persistently neutropenic rabbits. In vitro time-kill assays demonstrated that LY has concentration-dependent fungicidal activity. The pharmacokinetics of LY in the plasma of nonneutropenic rabbits suggested a linear relationship between dose and area under the curve (AUC). The times spent above the MIC during the experimental dosing interval of 24 h were 4 h for LY at 0.1 mg/kg of body weight/day (LY0.1), 8 h for LY at 0.25 mg/kg/day (LY0.25), 12 h for LY at 0.5 mg/kg/day (LY0.5), and 20 h for LY at 1 mg/kg/day (LY1). Antifungal therapy was administered to infected rabbits for 10 days starting 24 h after the intravenous (i.v.) inoculation of 10(3) Candida albicans blastoconidia. Study groups consisted of untreated controls (UCs) and animals treated with amphotericin B (AmB; 1 mg/kg/day i.v.), fluconazole (FLU; 10 mg/kg/day i.v.), and LY0.1, LY0.25, LY0.5, or LY1 i.v. Rabbits treated with LY0.5, LY1, AmB, and FLU had similarly significant clearance of C. albicans from the liver, spleen, kidney, lung, vena cava, and brain in comparison to that for UCs. There was a dose-dependent clearance of C. albicans from tissues in response to LY. Among rabbits treated with LY0.1 there was a significant reduction of C. albicans only in the spleen. In animals treated with LY0.25 there was a significant reduction in all tissues but the brain. By comparison, LY0.5 and LY1 cleared all tissues, including the brain, of C. albicans. These in vivo findings were consistent with the results of in vitro time-kill assays. A dose-dependent effect of altered cell wall morphology was observed among UCs and animals treated with LY0.1, and LY0.25, with a progressive transition from hyphal structure to disrupted yeast forms. Serum creatinine levels were higher and serum potassium levels were lower in AmB-treated rabbits than in UCs and LY- and FLU-treated rabbits. LY0.5 and LY1 were well tolerated, displayed predictable pharmacokinetics in plasma, and had activities comparable to those of AmB and FLU in the treatment of disseminated candidiasis in persistently neutropenic rabbits.

Antifungal susceptibility of Candida isolates at the American University of Beirut Medical Center

For the first time from Lebanon, the antifungal susceptibility patterns of 70 consecutive clinical candida isolates (each from one patient) representing 48 C. albicans, 12 C. tropicalis, 6 C. parapsilosis, 2 C. kruseii, and 2 C. (Torulopsis) glabrata were studied against amphotericin B (AP), 5-fluorocytosine (FC), ketoconazole (KE), fluconazole (FL), and itraconazole (IT) using the Epsilometer test (E-test; AB Biodisk, Solna, Sweden). The MIC90 (and MIC range, mg/l) determined, at 24 h incubation, for each antifungal agent against C. albicans were: AP 0.032 (< or = 0.002-0.064), FC 0.75 (0.023-2), KE 0.064 (0.002- > 32), FL 2 (0.064- > 256), and IT 0.19 (0.012-2), against C. tropicalis were: AP 0.016 (< 0.002-0.047), FC 0.125 (0.023-0.19), KE 0.094 (0.012-0.19), FL 2 (0.5-2), and IT 0.5 (0.047-1) and against C. parapsilosis were: AP < 0.002 (< 0.002-0.002), FC 0.047 (0.003-0.5), KE 0.004 (0.002-0.004), FL 0.125 (0.032-0.19), and IT 0.004 (< 0.002-0.004). Based on the NCCLS established MICs breakpoints, resistance was found among C. albicans to FL (MIC > or = 6 mg/l) and IT (MIC > or = 1 mg/l) in 6 and 4%, respectively, and among C. tropicalis to IT in 17% of the isolates. The susceptibility dependent upon dose (S-DD) was noted only to IT (MIC 0.25-0.5 mg/l) among C. albicans (8%) and C. tropicalis (58%). MICs determination at 48 h incubation were higher, showed more resistance rates and more endpoint trailing particularly with the azoles drugs. The small numbers of C. kruseii and C. glabrata preclude providing meaningful results. Thus, this study indicates that the antifungal susceptibility by E-test can be conveniently incorporated and performed in a hospital-based clinical laboratory. Despite the uniform susceptibility to AP and FC, resistance to azoles drugs is encountered in a range of 4-17% among candida isolates in this country.