Roy L. Hopfer

Systemic mycosis due to trichosporon cutaneum a report of two additional cases

Two additional cases of systemic mycosis due to Trichosporon cutaneum are reported and are compared with the previously published case of Rivera and Cangir. Both patients (a four‐year‐old male and a 57‐year‐old female) had acute leukemia for which they were receiving chemotherapy, and both presented with fever that was unresponsive to conventional antibiotics. Both had positive blood cultures for Trichosporon cutaneum. The disease was further documented in the four‐year‐old male by renal biopsy and by bone marrow culture; he was treated with apparent success with amphotericin B. However, the 57‐year‐old female died shortly after the beginning of similar treatment, and autopsy demonstrated involvement of the left kidney, spleen, bone marrow, and liver. The organism in both these cases, as well as the case of Rivera and Cangir, exhibited both hyphal and yeastlike forms in tissue sections. We believe that the therapeutic success in the case of the four‐year‐old male was primarily related to his remission from leukemia.

Amphotericin B Susceptibility Testing of Yeasts with a Bactec Radiometric System

The effect of amphotericin B on CO2 production was studied using a Bactec 225. A radiometric procedure for yeast susceptibility testing that requires 3 h of incubation was developed. A total of 48 yeast isolates was tested in this system and the results were correlated to tube dilution studies. The drug concentration causing at least a 44% decrease in CO2 production correlated to the tube dilution minimal inhibitory concentration in 85% of isolates tested and was within one tube dilution of the minimal inhibitory concentration in over 95% of yeasts tested.

Radiometric Determination of the Concentration of Amphotericin B in Body Fluids

A new assay was developed to determine the concentration of amphotericin B in body fluids. The Bactec radiometric system was used to measure CO2 production by a test strain, Candida albicans MDA 448, in the presence of amphotericin B. After 5-h incubation, drug concentrations as low as 0.2 μg/ml could be detected. The results are comparable to those of the commonly used agar diffusion assay with Paecilomyces varioti.