Cancer Research Institute and Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-2404, USA.
Med Mycol. 2010 Mar;48(2):421-6. doi: 10.1080/13693780903136879.
The fungal opportunist Cryptococcus neoformans forms biofilms in vitro and in vivo. C. neoformans has an unusual ability to grow over a wide range of temperatures, and is one of only two species in the genus able to grow at 37 degrees C. The optimum growth temperature in the laboratory is 30 degrees C, but Clinical and Laboratory Standards Institute (CLSI) planktonic susceptibility testing is performed at 35 degrees C. We investigated whether these growth temperatures affected C. neoformans biofilm formation and drug resistance. Biofilms of 30 strains of C. neoformans were grown at 30 degrees C or 35 degrees C, and antifungal susceptibilities evaluated at 30 degrees C or 35 degrees C using minimum biofilm eradication endpoints. At 35 degrees C, biofilms from 40% of the strains were more susceptible to flucytosine, 30% were more susceptible to nystatin, 27% were more susceptible to amphotericin, and 20% were more susceptible to fluconazole, as compared to 30 degrees C. The reverse, that is an increased susceptibility at 30 degrees C, only occurred with a single strain using nystatin or fluconazole. For the remaining strains, biofilm susceptibility was equivalent at the two temperatures. Biofilm colony forming units (CFU)s, as measured indirectly by 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction, were greater at 35 degrees C than at 30 degrees C for the majority of the strains. Thus, growth temperature does affect C. neoformans biofilm properties, but factors other than relative biofilm CFUs/ml must be involved in the increased drug susceptibility at 35 degrees C.
真菌机会主义者新型隐球菌在体外和体内形成生物膜。新型隐球菌具有在广泛温度范围内生长的非凡能力，是仅有的两个能够在 37°C 下生长的属种之一。实验室的最佳生长温度为 30°C，但临床和实验室标准协会（CLSI）浮游生物药敏试验在 35°C 下进行。我们研究了这些生长温度是否会影响新型隐球菌生物膜的形成和耐药性。将 30 株新型隐球菌的生物膜在 30°C 或 35°C 下生长，并在 30°C 或 35°C 下使用最小生物膜清除终点评估抗真菌药物敏感性。在 35°C 下，与 30°C 相比，40%的菌株的生物膜对氟胞嘧啶的敏感性更高，30%的菌株对制霉菌素的敏感性更高，27%的菌株对两性霉素的敏感性更高，20%的菌株对氟康唑的敏感性更高。相反，只有在使用制霉菌素或氟康唑时，单个菌株的敏感性在 30°C 下增加。对于其余菌株，生物膜的敏感性在两种温度下是等效的。通过 2,3-双（2-甲氧基-4-硝基-5-磺苯基）-2H-四唑-5-羧基苯胺（XTT）还原间接测量的生物膜集落形成单位（CFU），对于大多数菌株，在 35°C 下比在 30°C 下更大。因此，生长温度确实会影响新型隐球菌生物膜特性，但在 35°C 下增加药物敏感性的因素除了相对生物膜 CFU/ml 之外，还必须涉及其他因素。
