Biomedical subjects
Publications and source records attributed to Victor Paetznick.
Zone diameters for anidulafungin by disk diffusion for 139 isolates of C. parapsilosis were compared with MICs by NCCLS M27-A2 broth microdilution. The comparison was poor unless the disks were prepared by dissolving anidulafungin in 1% dimethyl sulfoxide plus 0.1% Tween 80 and testing on Mueller-Hinton agar flooded with glucose and methylene blue.
To evaluate methods for differentiating Candida albicans and Candida dubliniensis, 772 putative C. albicans bloodstream isolates were tested for growth at 37 and 42 degrees C. Isolates showing no growth at 42 degrees C, abundant chlamydospore production, and the sugar assimilation pattern of the type strain were confirmed by DNA-based procedures to be C. dubliniensis.
We investigated the in vitro interaction of caspofungin and amphotericin B for clinical isolates of Aspergillus and FUSARIUM: Synergy tests were performed using the checkerboard method and following the NCCLS M38-P guidelines in Antibiotic Medium 3 broth supplemented to 2% glucose. Antagonism was not observed for any of the isolates tested. Caspofungin and amphotericin B were synergistic or synergistic to additive for at least half of the isolates.
We compared the disk diffusion and broth microdilution methods for susceptibility testing of caspofungin against Aspergillus (n = 78) and Fusarium (n = 22) isolates. Microdilution testing followed the NCCLS M-38P guidelines but was performed in antibiotic medium 3 supplemented to 2% glucose (AM3). Disk diffusion assays were performed on AM3 agar plates with a 2- micro g caspofungin disk. By both methods, caspofungin showed favorable activity against Aspergillus isolates and no activity against Fusarium isolates. In the disk-based format, intrazonal growth that was not influenced by the drug concentration gradient was consistently observed for all of the Aspergillus isolates tested.
We investigated the in vitro activity of nystatin and liposomal nystatin against 103 Candida isolates to determine the effect of both time and medium on MICs. We also compared the nystatin MICs with those of amphotericin B and fluconazole. Testing was performed in accordance with the National Committee for Clinical Laboratory Standards M27-A microdilution methodology with RPMI 1640, RPMI 1640 supplemented with glucose to 2% (RPMI-2), and antibiotic medium 3 supplemented with glucose to 2% (AM3). While nystatin MICs were similar to or slightly lower than liposomal nystatin MICs in RPMI 1640 and RPMI-2, they were markedly higher than liposomal nystatin MICs in AM3. Use of AM3 and determination of the MIC after 24 h of incubation provided a slightly wider range of liposomal nystatin MICs (0.06 to >16 microg/ml). Under these conditions, the MICs at which 90% of isolates were inhibited of nystatin and liposomal nystatin were 2 and 1 microg/ml, respectively. Nystatin and liposomal nystatin in general showed good activity against all Candida spp. tested. Although the MICs of nystatin and liposomal nystatin tended to rise in parallel with the amphotericin B MICs, nystatin and liposomal nystatin MICs of 1 to 2 and 0.5 to 1 microg/ml, respectively, were obtained for seven and six, respectively, of nine isolates for which amphotericin B MICs were >or=0.25 microg/ml. No correlation between fluconazole and nystatin or liposomal nystatin MICs was observed. As amphotericin B MICs of >or=0.25 microg/ml correlate with in vitro resistance, these results suggest that liposomal nystatin might have activity against some amphotericin B-resistant isolates. In vivo testing in animal models is required for clarification of this issue.