医源性免疫抑制后堪萨斯分枝杆菌与鼠伤寒沙门氏菌的混合感染：一例报告

《BMC Infectious Diseases》：Disseminated Mycobacterium kansasii and Salmonella Typhimurium co-infection following iatrogenic immunosuppression: a case report

　　

摘要

背景

堪萨斯分枝杆菌与鼠伤寒沙门氏菌的播散性共感染极为罕见，尤其是在没有明显免疫缺陷的患者中。本病例描述了此类共感染独特的疾病进展过程以及医源性诱因。

病例介绍

一名61岁的男性，患有未控制的糖尿病，出现反复发热并伴有腋窝淋巴结肿大。检测发现炎症指标升高。脑部磁共振成像显示右侧顶叶脓肿伴硬膜下脓肿。血液培养以及血液和脑脊液的宏基因组下一代测序确认存在鼠伤寒沙门氏菌感染。胸部计算机断层扫描显示双肺存在炎症。脾脏的增强CT/MRI检查显示脾脏肿大，强化程度不均，还有多处小的强化结节。超声检查发现全身淋巴结肿大，尤其是腋窝部位。对右侧腋窝淋巴结进行切除后，病理检查、培养及宏基因组下一代测序均确认为堪萨斯分枝杆菌感染。该患者被诊断为堪萨斯分枝杆菌（累及淋巴结、肺部和脾脏）与鼠伤寒沙门氏菌（累及血液和大脑）的播散性共感染。HIV检测结果为阴性，抗干扰素-γ自身抗体和干扰素-γ水平也在正常范围内。从临床病程来看，最初为堪萨斯分枝杆菌引起的肺部和淋巴系统感染，之后因摄入生猪胆囊而引发沙门氏菌血症。随后由于使用环孢素/泼尼松等免疫抑制剂，导致两种病原体进一步播散至大脑、淋巴结和脾脏。经过长期抗菌治疗，病情得以控制。

结论

本病例展示了一种罕见的堪萨斯分枝杆菌与鼠伤寒沙门氏菌的播散性共感染情况，最初表现为非结核分枝杆菌感染，之后因摄入生猪胆囊而并发沙门氏菌病，且两种病原体的播散都与免疫功能下降有关。该病例强调了需要警惕非典型病原体，并谨慎使用免疫抑制剂。

背景

Disseminated Mycobacterium kansasii and Salmonella Typhimurium co-infection is exceptionally rare, particularly in patients without overt immunodeficiency. This case describes a unique disease progression and iatrogenic drivers in such co-infections.

Case presentation

A 61-year-old male with uncontrolled diabetes presented with recurrent fever accompanied by axillary lymph node enlargement. Elevated inflammatory markers were noted. Brain magnetic resonance imaging (MRI) revealed a right parietal abscess with subdural empyema. Blood cultures and metagenomic Next-Generation Sequencing (mNGS) of blood and cerebrospinal fluid (CSF) confirmed Salmonella Typhimurium infection. Chest computed tomography (CT) demonstrated bilateral pulmonary inflammation. Contrast-enhanced CT/MRI of the spleen showed splenomegaly with heterogeneous enhancement and diffuse small enhancing nodules. Ultrasound revealed generalized lymph node enlargement, particularly axillary. Right axillary lymph node excision pathology, culture and mNGS confirmed Mycobacterium kansasii. The patient was diagnosed with disseminated Mycobacterium kansasii (lymph nodes, lungs, and spleen) and Salmonella Typhimurium (bloodstream, brain) co-infection. HIV testing was negative, while anti-interferon-γ autoantibodies and interferon-γ levels were within normal ranges. Clinical trajectory suggested initial Mycobacterium kansasii pulmonary and lymphatic infection, followed by Salmonella bacteremia after ingesting raw pig gallbladders. Subsequent immunosuppression (cyclosporine/prednisone) triggered disseminated co-infection (brain, lymph nodes, spleen). Prolonged antimicrobial therapy achieved remission.

Conclusions

This case describes a rare dispersed co-infection with Mycobacterium kansasii and Salmonella Typhimurium, initially presenting as a non-tuberculous mycobacterial infection and later complicated by salmonellosis due to consumption of raw pig gallbladders. The spread of both pathogens was facilitated by immunosuppression. It underscores the importance of considering atypical pathogens and using immunosuppressive therapies carefully.