BACKGROUND In the past urine was considered sterile. Through the introduction of next generation sequencing, it has become clear that a urinary microbiome exists. Acute kidney injury (AKI) represents a major threat to kidney transplant recipients. Remarkable changes in the urinary metabolome occur during AKI, which may influence the urinary microbiome. To our knowledge, this is the first study that examines the urinary microbiome in renal transplant recipients (RTX) and non-transplant recipients (nRTX) at time of AKI. METHODS In this cross-sectional pilot-study the urinary microbiome of 21 RTX and 9 nRTX with AKI was examined. Clean catch morning urine samples were obtained from all patients on the first day of AKI diagnosis. AKI was defined according to KDIGO guidelines. Urinary microbiota and the urinary metabolome during AKI were assessed in one patient. 16S rRNA sequencing was performed. Sequences were processed using UPARSE-pipeline for operational taxonomic units (OTU) and taxon finding. RESULTS We successfully extracted and sequenced bacterial DNA from 100% of the urine samples. All 30 patients revealed at least 106,138 reads. 319 OTU and 211 different genera were identified. The microbiotic diversity richness in the RTX group was no different from the nRTX group. Eighteen genera were solely present in nRTX and 7 in RTX. CONCLUSIONS The urinary microbiome at time of AKI showed different bacterial genera in RTX compared to nRTX. The nRTX group exhibited no different diversity to the RTX group. Irrespective of the status of a previous renal transplantation, the urinary microbiome comprised > 210 different genera. An intraindividual change in microbiota diversity and richness was observed in one study patient during recovery from AKI.

中文翻译：

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尿液微生物组显示急性肾损伤时肾移植受者和非移植患者的不同细菌属 - 一项初步研究。

背景 过去，尿液被认为是无菌的。通过引入下一代测序，很明显尿液微生物组的存在。急性肾损伤 (AKI) 是对肾移植受者的主要威胁。在 AKI 期间，尿液代谢组会发生显着变化，这可能会影响尿液微生物组。据我们所知，这是第一项检查 AKI 时肾移植受者 (RTX) 和非移植受者 (nRTX) 尿液微生物组的研究。方法 在这项横断面试点研究中，检查了 21 个 RTX 和 9 个 nRTX 与 AKI 的尿液微生物组。在 AKI 诊断的第一天，从所有患者身上获取了干净的晨尿样本。AKI 是根据 KDIGO 指南定义的。在一名患者中评估了 AKI 期间的尿液微生物群和尿液代谢组。进行了 16S rRNA 测序。使用 UPARSE-pipeline 处理序列以进行操作分类单元 (OTU) 和分类单元查找。结果 我们成功地从 100% 的尿液样本中提取并测序了细菌 DNA。所有 30 名患者均显示至少 106,138 个读数。确定了 319 个 OTU 和 211 个不同的属。RTX 组的微生物多样性丰富度与 nRTX 组没有区别。18 个属仅存在于 nRTX 中，7 个属仅存在于 RTX 中。结论 与 nRTX 相比，AKI 时的尿液微生物组在 RTX 中显示出不同的细菌属。nRTX 组与 RTX 组没有表现出不同的多样性。无论先前肾移植的状态如何，尿液微生物组包括 > 210 种不同的属。在 AKI 恢复期间，在一名研究患者中观察到了微生物群多样性和丰富度的个体内变化。