Branda John A, Ferraro Mary Jane, Kratz Alexander
Division of Laboratory Medicine, Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass, USA.
Arch Pathol Lab Med. 2007 Jan;131(1):97-101. doi: 10.5858/2007-131-97-SOPBSR.
Case reports have described detection of candidemia by examination of peripheral blood smears. It is unclear whether this method has wider applicability for early detection of fungemia.
To determine the sensitivity of smear review for detecting candidemia.
Normal and cytopenic blood was spiked with increasing concentrations of yeast. Smears were prepared and reviewed by a pathologist and by technical staff. Staff members blinded to the purpose of the study first performed a routine slide review and then a targeted review for yeast.
The pathologist detected isolated yeast forms at a concentration of 1 to 5 x 10(5) colony-forming units (CFU)/mL. When blinded to the purpose of the study, technical staff could detect Candida in most samples when the yeast concentration was 1 to 5 x 10(7) CFU/mL, but found it in only a small fraction of samples with lower concentrations. When asked to examine the smears specifically for yeast, they could detect it in most samples containing 1 to 5 x 10(6) CFU/mL.
Detection of candidemia by peripheral blood smear examination requires a yeast concentration of 1 to 5 x 10(5) CFU/mL or greater. This degree of fungemia is unusual; therefore, detection of candidemia by blood smear review will not be possible in most cases. Sensitivity of smear review for yeast detection is greatly increased if the microscopist is specifically directed to look for the presence of yeast.
病例报告描述了通过检查外周血涂片检测念珠菌血症。尚不清楚这种方法对于真菌血症的早期检测是否具有更广泛的适用性。
确定涂片检查检测念珠菌血症的敏感性。
将正常血液和血细胞减少的血液加入浓度不断增加的酵母。制备涂片并由病理学家和技术人员进行检查。对研究目的不知情的工作人员首先进行常规玻片检查，然后针对性检查酵母。
病理学家在酵母浓度为1至5×10⁵集落形成单位（CFU）/mL时检测到单个酵母形态。当对研究目的不知情时，技术人员在酵母浓度为1至5×10⁷CFU/mL时能在大多数样本中检测到念珠菌，但在较低浓度的样本中仅能在一小部分样本中检测到。当被要求专门检查涂片以寻找酵母时，他们能在大多数含有1至5×10⁶CFU/mL的样本中检测到酵母。
通过外周血涂片检查检测念珠菌血症需要酵母浓度达到1至5×10⁵CFU/mL或更高。这种程度的真菌血症并不常见；因此，在大多数情况下通过血涂片检查检测念珠菌血症是不可能的。如果显微镜检查人员专门被指示寻找酵母的存在，涂片检查检测酵母的敏感性会大大提高。
