Institute for Food Safety and Hygiene, Section of Veterinary Bacteriology, University of Zurich, Zurich, Switzerland.
Institute of Veterinary Pathology, University of Zurich, Zurich, Switzerland.
Transbound Emerg Dis. 2021 Mar;68(2):573-586. doi: 10.1111/tbed.13717. Epub 2020 Jul 20.
The occurrence of mycobacterial infections in different hosts and their implication as obligate or opportunistic pathogens remain mainly unclear. In addition to the well-known pathogenic members of the Mycobacterium tuberculosis - complex (MTBC), over 180 non-tuberculous mycobacteria (NTM) species have been described. Although the large majority of the NTM is assumed to be non-pathogenic to most individuals, an increasing trend in NTM infections has been observed over the last decades. The reasons of such augmentation are probably more than one: improved laboratory diagnostics, an increasing number of immunocompromised patients and individuals with lung damage are some of the possible aspects. Mandibular lymph nodes of 176 hunted wild boars from the pre-Alpine region of Canton Ticino, Switzerland, were collected. Following gross inspection, each lymph node was subjected to culture and to an IS6110 based real-time PCR specific for MTBC members. Histology was performed of a selection of lymph nodes (n = 14) presenting gross visible lesions. Moreover, accuracy of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) species identification was compared with sequence analysis of a combination of housekeeping genes. Mycobacteria of the MTBC were detected in 2.8% of the wild boars (n = 5; CI 1.2-6.5) and were all confirmed to be Mycobacterium microti by molecular methods. In addition, based on the examined lymph nodes, NTM were detected in 57.4% (n = 101; CI 50.0-64.5) of the wild boars originating from the study area. The 111 isolates belonged to 24 known species and three potentially undescribed Mycobacterium species. M. avium subsp. hominissuis thereby predominated (22.5%) and was found in lymph nodes with and without macroscopic changes. Overall, the present findings show that, with the exception of undescribed Mycobacterium species where identification was not possible (3.6%; 4/111), MALDI-TOF MS had a high concordance rate (90.1%; 100/111 isolates) to the sequence-based reference method.
分枝杆菌感染在不同宿主中的发生及其作为专性或机会性病原体的意义仍主要不清楚。除了众所周知的结核分枝杆菌复合群（MTBC）致病成员外，已经描述了超过 180 种非结核分枝杆菌（NTM）物种。尽管大多数 NTM 被认为对大多数个体没有致病性，但在过去几十年中，NTM 感染的趋势一直在增加。这种增加的原因可能不止一个：实验室诊断的改善、免疫功能低下患者和肺损伤患者的数量增加是一些可能的方面。收集了来自瑞士提契诺州前阿尔卑斯地区的 176 头被猎杀野猪的下颌淋巴结。进行大体检查后，对每个淋巴结进行培养，并使用针对 MTBC 成员的基于 IS6110 的实时 PCR 进行检测。对呈现大体可见病变的选定淋巴结（n=14）进行组织学检查。此外，比较了基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）物种鉴定的准确性与管家基因组合的序列分析。在 2.8%（n=5；CI 1.2-6.5）的野猪中检测到 MTBC 的分枝杆菌，所有这些分枝杆菌均通过分子方法确认为微小分枝杆菌。此外，基于检查的淋巴结，在来自研究区域的 57.4%（n=101；CI 50.0-64.5）的野猪中检测到 NTM。111 株分离株属于 24 种已知物种和 3 种潜在未描述的分枝杆菌物种。禽分枝杆菌亚种。人源感染（22.5%），并在有和没有宏观变化的淋巴结中发现。总体而言，目前的研究结果表明，除了无法识别的未描述分枝杆菌物种（3.6%；4/111）外，MALDI-TOF MS 与基于序列的参考方法具有很高的一致性（90.1%；111 株分离株中的 100/111）。
