Varga I, Sóczó G, Kardos G, Majoros L
Faculty of Dentistry, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
J Antimicrob Chemother. 2008 Jul;62(1):149-52. doi: 10.1093/jac/dkn144. Epub 2008 Apr 4.
We evaluated the in vitro activity of caspofungin against Candida dubliniensis strains using MIC and minimum fungicidal concentration (MFC) measurements and time-kill methodology.
We used six C. dubliniensis clinical isolates and the CD 36 type strain. MICs and MFCs of caspofungin were determined using the standard broth microdilution method with normal (10(3) cells/mL) and elevated (10(5) cells/mL) starting inocula in RPMI-1640 and antibiotic medium 3 (AM3). MIC was determined after 24 h, and plating for MFC determination was performed after 48 h. In time-kill tests, all strains were tested at 0.06-16 mg/L caspofungin concentrations in RPMI-1640 and AM3.
In RPMI-1640, the MIC range was 0.06-8 mg/L. Trailing growth was observed regardless of the starting inoculum after 48 h, but not after 24 h. In AM3 regardless of starting inoculum, MICs were 0.03 mg/L. After 48 h, trailing was not detected; two isolates grew at a concentration of 8 mg/L using 10(5) cells/mL as the starting inoculum [paradoxical growth (PG)]. All MFCs in RPMI-1640 and AM3 were >8 and < or =0.12 mg/L, respectively. In AM3, all but a single isolate showed PG in the MFC tests. Time-kill tests confirmed the results obtained by MFC tests both in RPMI-1640 and AM3.
In vitro activity of caspofungin against C. dubliniensis depended on the starting inoculum and medium used. Using AM3 eliminated trailing from MIC determinations but not PG in MIC, MFC and time-kill tests.
我们采用最低抑菌浓度（MIC）、最低杀菌浓度（MFC）测定法及时间杀菌方法评估了卡泊芬净对都柏林念珠菌菌株的体外活性。
我们使用了6株都柏林念珠菌临床分离株及CD 36标准菌株。采用标准肉汤微量稀释法，以正常接种量（10³个细胞/mL）和高接种量（10⁵个细胞/mL）在RPMI-1640和抗生素培养基3（AM3）中测定卡泊芬净的MIC和MFC。24小时后测定MIC，48小时后进行平板接种以测定MFC。在时间杀菌试验中，所有菌株在RPMI-1640和AM3中卡泊芬净浓度为0.06 - 16mg/L的条件下进行测试。
在RPMI-1640中，MIC范围为0.06 - 8mg/L。48小时后，无论初始接种量如何均观察到拖尾生长，但24小时后未观察到。在AM3中，无论初始接种量如何，MIC均为0.03mg/L。48小时后，未检测到拖尾现象；使用10⁵个细胞/mL作为初始接种量时，有2株分离株在8mg/L浓度下生长[反常生长（PG）]。RPMI-1640和AM3中的所有MFC分别>8mg/L和≤0.12mg/L。在AM3中，除1株分离株外，所有分离株在MFC试验中均显示PG。时间杀菌试验证实了在RPMI-1640和AM3中通过MFC试验获得的结果。
卡泊芬净对都柏林念珠菌的体外活性取决于所用的初始接种量和培养基。使用AM3可消除MIC测定中的拖尾现象，但在MIC、MFC和时间杀菌试验中不能消除PG。
