Abstract：
We aimed to evaluate whether the FilmArray blood culture identification (BCID) panel holds the ability to detect vanM-type vancomycin-resistant enterococci (VRE) clinical isolates effectively.
Twenty VRE clinical strains, including 10 vanA-type VRE and 10 vanM-type VRE, were collected from patients in five tertiary hospitals, Shanghai, China. By conventional PCR and sequencing, the strains were identified and van genotypes were confirmed. All VRE strains were investigated using the FilmArray BCID panel. All results, including enterococcus assay, vanA/B assay, DNA melting curves and melting temperature (Tm), were recorded. We also compared these results with those obtained via the conventional PCR and sequencing.
According to the instructions of the FilmArray BCID panel, the Enterococcus assay is used to identify species and vanA/B assay is used to detect van genes. In all vanA-type VRE, the Enterococcus assay and vanA/B assay were positive. The results correctly showed that the tested strains were VRE. However, in 10 vanM-type VRE, the Enterococcus assay was positive and vanA/B assay were negative. The results mistakenly showed that the tested strains were vancomycin-sensitive enterococci (VSE). In the vanA/B assay, the melting curves of vanM-type VRE were similar to that of vanA-type VRE, but the Tm values were lower. The Tm values were then compared against the expected Tm range for the vanA/B assay. The Tm values of vanM-type VRE fall outside the assay-specific Tm range, resulting in negative reports. Thus, by adjusting the expected Tm range for the Enterococcus assay, the FilmArray BCID panel holds the ability to detect vanM-type VRE.
The vanM-type VRE isolates can be effectively detected by optimizing the expected Tm range for the vanA/B assay.
Twenty VRE clinical strains, including 10 vanA-type VRE and 10 vanM-type VRE, were collected from patients in five tertiary hospitals, Shanghai, China. By conventional PCR and sequencing, the strains were identified and van genotypes were confirmed. All VRE strains were investigated using the FilmArray BCID panel. All results, including enterococcus assay, vanA/B assay, DNA melting curves and melting temperature (Tm), were recorded. We also compared these results with those obtained via the conventional PCR and sequencing.
According to the instructions of the FilmArray BCID panel, the Enterococcus assay is used to identify species and vanA/B assay is used to detect van genes. In all vanA-type VRE, the Enterococcus assay and vanA/B assay were positive. The results correctly showed that the tested strains were VRE. However, in 10 vanM-type VRE, the Enterococcus assay was positive and vanA/B assay were negative. The results mistakenly showed that the tested strains were vancomycin-sensitive enterococci (VSE). In the vanA/B assay, the melting curves of vanM-type VRE were similar to that of vanA-type VRE, but the Tm values were lower. The Tm values were then compared against the expected Tm range for the vanA/B assay. The Tm values of vanM-type VRE fall outside the assay-specific Tm range, resulting in negative reports. Thus, by adjusting the expected Tm range for the Enterococcus assay, the FilmArray BCID panel holds the ability to detect vanM-type VRE.
The vanM-type VRE isolates can be effectively detected by optimizing the expected Tm range for the vanA/B assay.
摘要：
目的：我们旨在评估FilmArray血液培养鉴定（BCID）小组是否具有有效检测vanM型耐万古霉素肠球菌（VRE）临床分离株的能力。
方法：20株VRE临床菌株，包括10个VanA型VRE和10个VanM型VRE，是从五家三级医院的病人那里收集的，上海,中国。通过常规PCR和测序，鉴定了菌株，并确认了van基因型。使用FilmArrayBCID面板研究所有VRE菌株。所有结果,包括肠球菌分析，vanA/B分析，DNA解链曲线和解链温度(Tm),被记录下来。我们还将这些结果与通过常规PCR和测序获得的结果进行了比较。
结果：根据FilmArrayBCID面板的说明，肠球菌测定法用于鉴定物种，vanA/B测定法用于检测van基因。在所有vanA型VRE中，肠球菌和vanA/B检测均为阳性。结果正确地表明,所测试的菌株为VRE。然而,在10个vanM型VRE中，肠球菌属试验阳性，vanA/B试验阴性。结果误认为受试菌株为万古霉素敏感肠球菌(VSE)。在vanA/B试验中,VanM型VRE的熔解曲线与VanA型VRE的熔解曲线相似，但Tm值较低。然后将Tm值与vanA/B测定的预期Tm范围进行比较。vanM型VRE的Tm值落在测定特异性Tm范围之外，导致负面报道。因此，通过调整肠球菌分析的预期Tm范围，FilmArrayBCID面板具有检测vanM型VRE的能力。
结论：通过优化vanA/B测定的预期Tm范围，可以有效地检测vanM型VRE分离株。
方法：20株VRE临床菌株，包括10个VanA型VRE和10个VanM型VRE，是从五家三级医院的病人那里收集的，上海,中国。通过常规PCR和测序，鉴定了菌株，并确认了van基因型。使用FilmArrayBCID面板研究所有VRE菌株。所有结果,包括肠球菌分析，vanA/B分析，DNA解链曲线和解链温度(Tm),被记录下来。我们还将这些结果与通过常规PCR和测序获得的结果进行了比较。
结果：根据FilmArrayBCID面板的说明，肠球菌测定法用于鉴定物种，vanA/B测定法用于检测van基因。在所有vanA型VRE中，肠球菌和vanA/B检测均为阳性。结果正确地表明,所测试的菌株为VRE。然而,在10个vanM型VRE中，肠球菌属试验阳性，vanA/B试验阴性。结果误认为受试菌株为万古霉素敏感肠球菌(VSE)。在vanA/B试验中,VanM型VRE的熔解曲线与VanA型VRE的熔解曲线相似，但Tm值较低。然后将Tm值与vanA/B测定的预期Tm范围进行比较。vanM型VRE的Tm值落在测定特异性Tm范围之外，导致负面报道。因此，通过调整肠球菌分析的预期Tm范围，FilmArrayBCID面板具有检测vanM型VRE的能力。
结论：通过优化vanA/B测定的预期Tm范围，可以有效地检测vanM型VRE分离株。
