Amoebic liver abscess (ALA) is regularly seen in travelers or immigrants from tropical countries. The diagnosis relies on liver imaging that is not specific and on the detection of anti-Entamoeba histolytica antibodies, which cannot distinguish an acute from a former infection. We tested whether E. histolytica DNA detection in serum can improve the diagnosis of ALA. We retrospectively tested available serum samples taken from patients with ALA and non-ALA space-occupying lesions of the liver between 1 January 2010 and 30 November 2019. The quantitative PCR (qPCR) assay tested specifically amplifies a 99-bp fragment of the small-subunit rRNA gene of E. histolytica. We analyzed 76 samples (19 ALA and 57 non-ALA samples) collected from 76 patients within 6 days before and after the antiamoebic treatment. Serum qPCR results were positive for 17 of 19 ALA patients and for none of the control patients (sensitivity and specificity were 89.5% and 100%, respectively). In parallel, the sensitivity and specificity of anti-E. histolytica antibody detection were 100% and 89.5%, respectively. The two false-negative qPCR results may be explained by ongoing metronidazole treatment or a possible persistent seropositivity that was not caused by the current liver abscess. Additionally, of 12 abscess pus aspirates (5 from ALA and 7 from non-ALA samples) tested, 5 were qPCR positive and 7 were qPCR negative, with concordant results in serum. This study demonstrates that cell-free circulating E. histolytica DNA can be detected in serum in ALA. This may assist in both positive diagnoses and treatment efficacy follow-up. The origin of this circulating DNA remains to be investigated.

中文翻译：

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疑似阿米巴肝脓肿患者血清中溶组织性变形杆菌DNA检测。

来自热带国家的旅行者或移民经常见到阿米巴肝脓肿（ALA）。诊断依赖于非特异性的肝脏影像学和抗溶组织变形虫抗体的检测，该抗体不能区分急性感染和以前的感染。我们测试了血清中溶组织性大肠杆菌DNA检测是否可以改善ALA的诊断。我们回顾性地测试了2010年1月1日至2019年11月30日期间从患有ALA和非ALA占位性肝脏病变的患者中获得的血清样品。所测试的定量PCR（qPCR）分析特异性扩增了小分子小分子小鼠的99 bp片段溶血性大肠杆菌亚基rRNA基因。我们分析了抗氧治疗前后6天内从76例患者中收集的76份样品（19份ALA和57份非ALA样品）。血清qPCR结果在19例ALA患者中有17例是阳性，在所有对照患者中均没有（敏感性和特异性分别为89.5％和100％）。同时，抗溶组织性大肠杆菌的敏感性和特异性抗体检出率分别为100％和89.5％。这两种假阴性的qPCR结果可能由正在进行的甲硝唑治疗或可能不是由当前肝脓肿引起的持续血清反应阳性所解释。此外，在测试的12个脓肿抽吸物中（5个来自ALA，7个来自非ALA样品），qPCR阳性5个，qPCR阴性7个，血清结果一致。这项研究表明，可以在ALA血清中检测到无细胞循环的溶血性大肠杆菌。这可能有助于阳性诊断和治疗效果的随访。这种循环DNA的起源仍有待研究。