Standardization of a pcr for molecular diagnosis of microsporum canis in samples of fur and crusts of dogs and cats

ABSTRACT The aim of this study was to standardize a Polymerase Chain Reaction protocol (PCR) for the detection of Microsporum canis in fur and/or crusts of dogs and cats. 48 samples previously identified by culture were selected. Of these, 23 were positive for dermatophytes in culture. PCR was standardized from drawn primers whose target is M. canis. A total of 61% (14/23) of the dermatophyte positive samples were identified as M. canis in culture. Of this total, 71.4% (10/14) presented a fragment of 218bp compatible with that expected for the fungal species target of the reaction. A sensitivity of 71.4% and specificity of 100% in the PCR were observed, in addition to a good agreement between the techniques (Kappa: 0.78; P< 0.0001). The protocol used in this study showed high specificity in the detection of M. canis directly from fur and/or crusts of dogs and cats, making possible a faster and more specific diagnosis. This protocol could be used as a confirmatory method, speeding the detection of M. canis.

摘要 本研究旨在建立一套标准化的聚合酶链式反应（Polymerase Chain Reaction，PCR）检测方法，用于从犬、猫的毛发和/或痂皮样本中检测犬小孢子菌（Microsporum canis）。本研究选取了48份此前经真菌培养法鉴定的样本，其中23份在皮肤癣菌培养检测中呈阳性。本研究采用靶向犬小孢子菌的引物建立了标准化PCR检测体系。在皮肤癣菌培养阳性的样本中，共有61%（14/23）经培养鉴定为犬小孢子菌阳性；在上述14份犬小孢子菌培养阳性样本中，71.4%（10/14）扩增出了与该反应靶标真菌预期片段大小一致的218bp特异性条带。该PCR检测方法的灵敏度为71.4%，特异度达100%，且该方法与培养法之间具有良好的一致性（Kappa系数：0.78；P<0.0001）。本研究所用的检测体系可直接从犬、猫的毛发和/或痂皮样本中高特异性地检测犬小孢子菌，能够实现更快速且特异性更强的诊断。该检测体系可作为犬小孢子菌检测的确认方法，加速其临床检测进程。