Division of Clinical Laboratories, University of Fukui Hospital, Fukui, Japan.
J Microbiol Methods. 2010 Sep;82(3):198-204. doi: 10.1016/j.mimet.2010.06.002. Epub 2010 Jun 9.
We attempted to develop a new specific antibody detection method for discriminating infection state from colonization state in hospitalized immunocompromised patients with a positive sputum culture for Pseudomonas aeruginosa. Serum samples from 65 patients with P. aeruginosa in sputum culture (total PA patients), including 24 patients with P. aeruginosa-related pulmonary infections (PA infection group) and 21 patients without pulmonary infections (PA colonization group), as well as samples from 20 patients positive for other bacteria in blood culture (non-PA infection group) and 38 healthy controls were examined and compared for IgG and IgA anti-P. aeruginosa antibodies by a newly developed enzyme-linked immunosorbent assay (ELISA). Both IgG and IgA antibody ELISA showed satisfactory reproducibility with low coefficient of variation (CV) percent, and western blotting analysis showed two protein bands as the corresponding antigens common to both antibodies. The serum levels of both antibodies in all the PA patients were higher than those in the healthy controls with high significance (p<0.0001). The PA infection group showed significantly higher mean levels of both IgG and IgA class antibodies than the PA colonization group, non-PA infection group and healthy controls (each, p<0.0001). In receiver operating characteristic (ROC) curves analysis to differentiate between total PA infections and the PA colonization group, the area under curve (AUC) of the IgA antibody (0.848) was significantly larger than the AUC of the IgG antibody (0.677) (p=0.019). At the optimal IgA antibody cutoff value for differentiation of 1.37 units/mL, the sensitivity and specificity of IgA anti-P. aeruginosa ELISA were 83.3% and 85.7%, respectively. These findings suggest that IgA antibody ELISA, rather than IgG antibody ELISA, may be useful for differentiating P. aeruginosa-related pneumonia from latent colonization in immunocompromised patients with a positive sputum culture.
我们试图开发一种新的特异性抗体检测方法，以区分住院免疫功能低下患者痰培养阳性铜绿假单胞菌的感染状态和定植状态。检测了 65 例痰培养铜绿假单胞菌阳性患者（总 PA 患者）的血清样本，包括 24 例铜绿假单胞菌相关肺部感染患者（PA 感染组）、21 例无肺部感染患者（PA 定植组）以及 20 例血培养阳性其他细菌患者（非 PA 感染组）和 38 例健康对照者的 IgG 和 IgA 抗铜绿假单胞菌抗体，采用新建立的酶联免疫吸附试验（ELISA）。IgG 和 IgA 抗体 ELISA 均具有良好的重现性，变异系数（CV）%低，Western blot 分析显示两条蛋白带为两种抗体的共同相应抗原。所有 PA 患者的血清抗体水平均显著高于健康对照组，差异有统计学意义（p<0.0001）。PA 感染组 IgG 和 IgA 类抗体的平均水平均显著高于 PA 定植组、非 PA 感染组和健康对照组（均 p<0.0001）。在区分总 PA 感染与 PA 定植组的受试者工作特征（ROC）曲线分析中，IgA 抗体的曲线下面积（AUC）（0.848）显著大于 IgG 抗体的 AUC（0.677）（p=0.019）。在区分 1.37 单位/ml 的最佳 IgA 抗体截断值时，IgA 抗铜绿假单胞菌 ELISA 的敏感性和特异性分别为 83.3%和 85.7%。这些发现表明，IgA 抗体 ELISA 可能比 IgG 抗体 ELISA 更有助于区分免疫功能低下患者痰培养阳性的铜绿假单胞菌相关肺炎与潜伏定植。
