Benoit Patrick, Wang Stephanie, Wang Catherine, Chakravarti Arpita, Villalba Julian A, Ali Ibne Karim M, Roy Shantanu, Sapp Sarah Gh, Reagan-Steiner Sarah, Nelson Kristoff, Cayrol Romain, Luong Me-Linh, Grand'Maison Sophie, Desjardins Michaël
Division of Infectious Diseases, Department of Medicine, Centre hospitalier de l'Université de Montréal (CHUM), Montreal, Quebec, Canada.
Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, Quebec, Canada.
J Assoc Med Microbiol Infect Dis Can. 2024 Jun 12;9(2):113-120. doi: 10.3138/jammi-2023-0036. eCollection 2024 Jun.
Free-living amoebas (FLAs) can cause severe and fatal central nervous system infections that are difficult to diagnose.
We present the case of a 74-year-old immunocompetent woman admitted for focal neurological symptoms with enhancing lesions in the right cerebellar hemisphere. A first cerebral biopsy showed granulomatous inflammation, but no microorganisms were identified. After transient clinical improvement, she eventually deteriorated 4 months after initial presentation, with an MRI confirming multiple new masses affecting all cerebral lobes.
A second brain biopsy revealed granulomatous and acute inflammation with organisms containing a large central nucleus with prominent karyosome, consistent with FLAs. Immunohistochemical and polymerase chain reaction assays performed at CDC were positive for spp, confirming the diagnosis of granulomatous amoebic encephalitis (GAE) caused by spp. The patient was treated with combination therapy recommended by CDC, but died a few days later. Upon histopathological rereview, amoebic cysts and trophozoites were identified by histochemical and immunohistochemical methods in the first cerebral biopsy.
FLA infections can be challenging to diagnose because of the low incidence, non-specific clinical and radiological presentation, lack of accessible diagnostic tools, and clinicians' unfamiliarity. This case highlights the importance of recognizing FLA as a potential cause of granulomatous encephalitis, even in the absence of risk factors, as early treatment might be associated with favourable outcomes in case reports. When suspected, CDC laboratories offer tests to confirm the diagnosis promptly.
自由生活阿米巴（FLAs）可引起严重且致命的中枢神经系统感染，难以诊断。
我们报告了一例74岁免疫功能正常的女性病例，因局灶性神经症状入院，右小脑半球有强化病灶。首次脑活检显示肉芽肿性炎症，但未发现微生物。经过短暂的临床改善后，她在初次就诊4个月后最终病情恶化，MRI证实多个新肿块累及所有脑叶。
第二次脑活检显示肉芽肿性和急性炎症，病原体含有一个大的中央核，核仁突出，与自由生活阿米巴一致。疾病控制与预防中心（CDC）进行的免疫组织化学和聚合酶链反应检测对 属呈阳性，证实了由 属引起的肉芽肿性阿米巴脑炎（GAE）的诊断。患者接受了CDC推荐的联合治疗，但几天后死亡。在组织病理学复查时，通过组织化学和免疫组织化学方法在首次脑活检中发现了阿米巴囊肿和滋养体。
由于发病率低、临床和影像学表现不特异、缺乏可用的诊断工具以及临床医生不熟悉，自由生活阿米巴感染可能难以诊断。该病例强调了即使在没有危险因素的情况下，认识到自由生活阿米巴是肉芽肿性脑炎的潜在病因的重要性，因为在病例报告中早期治疗可能与良好预后相关。当怀疑时，CDC实验室可提供检测以迅速确诊。
