Cantón Emilia, Pemán Javier, Espinel-Ingroff Ana, Martín-Mazuelos Estrella, Carrillo-Muñoz Alfonso, Martínez José Pedro
Unidad de Microbiología Experimental, Centro de Investigación, Hospital Universitario La Fe, Valencia, Spain.
J Antimicrob Chemother. 2008 Jan;61(1):135-8. doi: 10.1093/jac/dkm442. Epub 2007 Nov 22.
To evaluate the suitability of disc diffusion (DD) assay for testing posaconazole activity and to corroborate its activity against recently isolated yeasts by the CLSI reference microdilution M27-A2 method.
A total of 224 yeast isolates (7 species with 52 to 11 isolates each, and 15 species with 1 to 6 isolates) were evaluated, 125 were recent bloodstream isolates, 30 isolates from other sources and six ATCC isolates that included amphotericin B-resistant Candida albicans ATCC 200955, Candida lusitaniae (ATCC 200950, 200951, 200952 and 200953) and amphotericin B- and itraconazole-resistant Candida tropicalis ATCC 200956. MICs were determined at 24 and 48 h by following the CLSI guidelines, document M27-A2. DD testing was performed by following CLSI M44-A document with 5 microg posaconazole discs. Inhibition zone diameters were measured at the transition point at which growth decreased at both 24 and 48 h.
DD showed very good reproducibility, with coefficient of variability median value 4.56. Posaconazole demonstrated good in vitro activity against all clinical isolates, including the emerging species and amphotericin B-resistant ATCC isolates except for C. tropicalis ATCC 200956 (posaconazole MIC >or= 16 mg/L). Only 1.5% and 4.1% of isolates were inhibited by >2 mg/L posaconazole at 24 and 48 h. Good correlation was obtained between methods (R = 0.763 at 24 h and 0.602 at 48 h). DD detected posaconazole-resistant isolates (MIC > 2 mg/L).
DD could be an alternative to the microdilution reference method, as no major discrepancies were detected.
评估纸片扩散法（DD）检测泊沙康唑活性的适用性，并通过美国临床和实验室标准协会（CLSI）参考微量稀释法M27 - A2证实其对近期分离酵母的活性。
共评估了224株酵母分离株（7个菌种，每个菌种有11至52株；15个菌种，每个菌种有1至6株），其中125株为近期血流感染分离株，30株来自其他来源，6株为美国典型培养物保藏中心（ATCC）分离株，包括对两性霉素B耐药的白色念珠菌ATCC 200955、葡萄牙念珠菌（ATCC 200950、200951、200952和200953）以及对两性霉素B和伊曲康唑耐药的热带念珠菌ATCC 200956。按照CLSI指南文件M27 - A2在24小时和48小时测定最低抑菌浓度（MIC）。采用含5微克泊沙康唑纸片按照CLSI M44 - A文件进行DD试验。在24小时和48小时生长均下降的转折点处测量抑菌圈直径。
DD显示出非常好的重复性，变异系数中位数为4.56。泊沙康唑对所有临床分离株均表现出良好的体外活性，包括新出现的菌种以及除热带念珠菌ATCC 200956（泊沙康唑MIC≥16毫克/升）之外的对两性霉素B耐药的ATCC分离株。在24小时和48小时，分别仅有1.5%和4.1%的分离株被>2毫克/升的泊沙康唑抑制。两种方法之间具有良好的相关性（24小时时R = 0.763，48小时时R = 0.602）。DD检测到了对泊沙康唑耐药的分离株（MIC>2毫克/升）。
由于未检测到重大差异，DD可作为微量稀释参考方法的替代方法。
