Cerebral vasculitis caused by Talaromyces marneffei and Aspergillus niger in a HIV-positive patient: a case report and literature review

Cerebral vasculitis is a long-standing but flourishing and fadeless research topic. Infections are a frequent cause of cerebral vasculitis, vital to diagnose due to involvement of specific anti-infection treatments. A 65-year-old man visited the hospital for his neurological symptoms without obvious inducements. After admission, radiological examination and comprehensive conventional microbiological tests (CMTs) revealed suspected intracranial infectious vasculitis. Metagenomic next-generation sequencing (mNGS) and reverse transcription-polymerase chain reaction further confirmed that his cerebral vasculitis was caused by Talaromyces marneffei (T. marneffei) and Aspergillus niger (A. niger) co-infection. The patient’s final diagnosis changed from initial herpetic encephalitis, due to the past history of cephalosome and facial herpes and non-significant antiviral therapeutic effects, to fungal cerebral vasculitis. The patient was discharged after use of targeted antifungal therapies on day 18 of his admission, and his associated symptoms disappeared completely at follow-up 3 weeks later. We first illustrated the presence of uncommon cerebral vasculitis caused by T. marneffei and A. niger in a human immunodeficiency virus-positive patient. In clinically suspected patients with infectious cerebral vasculitis, mNGS should be performed to detect potential pathogens if CMTs may not provide useful pathogenic clues, highlighting the importance of mNGS in the diagnosis and treatment of infectious diseases.


Introduction
Cerebral vasculitis is defined as inflammation occurring associated with destructive changes, occlusion, and infarction within the wall of intracranial blood vessels (Kraemer and Berlit 2021;Camuset et al. 2012). The prognosis of cerebral vasculitis, including infectious cerebral vasculitis, is closely related to early recognition and diagnosis due to its severity (Blancart et al. 2021;Wu et al. 2021). Thus, the key to understand infectious cerebral vasculitis is to get a good grasp of its underlying pathogens. However, conventional microbiological tests (CMTs) have competitive weaknesses, such as long turnaround time, complex process, low positive rate, and throughput. Metagenomic next-generation sequencing (mNGS), by contrast, directly detects the nucleic acid sequence of microorganisms in clinical specimens, skipping microbial culture (Gu et al. 2019;Alzahrani et al. 2021;Zhang et al. 2020), and covers a variety of pathogenic microorganisms including viruses, bacteria, fungi, and parasites quickly and objectively (Gu et al. 2019;Petersen et al. 2020). Here, we exemplified an old man who had clinically suspected viral encephalitis and was ultimately diagnosed as fungal cerebral vasculitis using mNGS. Additionally, this was the first case to report the presence of cerebral vasculitis caused by T. marneffei and A. niger in human immunodeficiency virus (HIV)-positive patient.

Case report
A 65-year-old man without obvious inducements was hospitalized for slow response, decreased speech and dysphagia. Two days ago, he went to the local hospital, and his brain computed tomography (CT) examination indicated cerebral infarction with a small amount of oozing blood. To seek for further diagnosis and treatment, he was transferred to our hospital with suspected herpetic encephalitis or arteriosclerotic cerebral infarction, considering that the patient had a past history of cephalosome, facial herpes, and type-2 diabetes. His blood pressure was 109/65 mmHg, pulse was 103 bpm, respiration was 20 bpm, and temperature was 36.8 °C on admission. Cerebrospinal fluid was obtained by lumbar puncture after admission, and then antiviral therapies (Acyclovir, 500 mg, every 8 h) were given.
The cerebrospinal fluid cytology examination indicated that the patient's white blood cell counts (15 × 10 6 /L; normal 0-8), red blood cell counts (480 × 10 6 /L; normal 0), total protein (2474.0 mg/L; normal 200-450), and lactate dehydrogenase (111.10 U/L; normal 3-40) levels significantly raised, while glucose level assay (1.93 mmol/L; normal 2.5-4.5) decreased. Cytological assay of his cerebrospinal fluid exhibited abnormal signs in the percentage of active monocytes (18%) and plasmacytes ( +) (Fig. 1a). Cerebrospinal fluid culture was negative. After admission, the brain magnetic resonance imaging (MRI) showed hemorrhagic infarction in the temporal lobe, which implied intracranial infectious vasculitis may occur (Fig. 1b). In order to confirm the diagnosis, we performed whole brain angiography on the seventh day after admission. It showed that the patient had multiple lesions in the cerebral artery, mainly in the posterior circulation. The initial part of the left vertebral artery was indistinct, the distal vessels were thin, and there was no progression far from V2. The right vertebral body was dominant, and the left posterior cerebral artery was occluded far away from P1 segment. The diagnosis of cerebral vascular inflammatory lesions was confirmed (Fig. 1c).
On day 3 of admission, the patient had thick sputum elimination with high fever (38.7℃). Lung CT examination showed that his physical condition worsened with pulmonary infection. And the patient's sputum culture was examined, but no significantly positive pathogen culture was identified. Intravenous injection of cefotaxime sodium at a dose of 2 g per 12 h was implemented to deaden his pulmonary infections empirically. Concurrently, mNGS was performed in SimcereDx Lab (Nanjing, China) to identify potential pathogens in cerebrospinal fluid due to disease progression. mNGS revealed 13 T. marneffei and 9 Aspergillus niger specific sequences with reads coverage of 0.0044% and 0.0014%, respectively (Fig. 2a, b). The following reverse transcription-polymerase chain reaction (PCR) test confirmed the pathogenic results of mNGS (Fig. 2c). Primer information of T. marneffei (101 bp): forward primer: 5-TTC CCG AGC GAG TGA CAG A − 3 and reverse primer 5-GCT TGT GTG TTG GGT GTG GT −3 and A. niger (500 bp): forward primer: 5-GGG CAA AGG GTT GGG TCT TC −3 and reverse primer 5′ GAC GAG GAC GGC ACG AGG A −3. Thus, his final diagnosis was adjusted to fungal intracranial vasculitis caused by T. marneffei and A. niger. And at the same time, his treatment options were changed into intravenous injection of amphotericin B from 3 mg on day 1, 5 mg on day 2, until 40 mg on day 10. In order to prevent the side effects, a small dose of dexamethasone 5 mg was given before use.
On day 10 of admission, high fever disappeared. On day 13, the lung CT examination showed significant remission of the local focus caused by pulmonary infection. The patient's symptoms improved and discharged on day 18 of admission after a long-term anti-infection. After leaving hospital, he was further treated with itraconazole 200 mg per 12 h. At follow-up 3 weeks later, the fever and neuronal disorders vanished completely.

Discussion
In this case, considering that the patient had a history of facial herpes and was not cured on his hospitalization, and the brain CT showed the temporal lobe lesion with hemorrhage, herpetic encephalitis was considered for prediagnosis; hence antiviral treatment was given. CMT results were negative for autoimmune encephalitis caused by HIV positivity. Genetically pathogenic analysis of T. marneffei and A. niger positive in cerebrospinal fluid excluded the possibility of herpetic infection-derived cerebral vasculitis. Meanwhile, cerebral angiography showed occlusion in the left posterior cerebral artery and hemorrhagic infarction lesions in the bilateral medial temporal lobe. Collectively, the diagnosis was finally adjusted to fungal cerebral  (Rao et al. 1978a). A systematic review of the fungal cerebral vasculitis was retrieved from Web of Science Core Collection, and up to May 28th, 2021, 20 papers had been published in total (Table 1). Fungal cerebral vasculitis frequently occurs in patients with severe cellular immunosuppression (hematopathy, transplantation, HIV infection, and immunosuppressive therapy), with a dismal prognosis (Jung et al. 2018;Leroy et al. 2020;Ermak et al. 2014;Eucker et al. 2000;Van Rooij et al. 2018). Infection-derived vasculitis is caused by angiogenic pathogens, including Aspergillus sp., Candida albicans, zygomycotina sp., Cryptococcus neoformans, and so on, and their etiopathogenesis can be summarized as follows: subarachnoidal meningitis, sinuses or orbital infection, and immune mechanism in the context of chronic infections (Lampros et al. 2021;Herlin et al. 2015;Thirunavukkarasu et al. 2021). Early recognition and diagnosis of cerebral vasculitis can, to a great extent, alleviate the risk of its severity and improve prognosis (Rao et al. 1978a;Jung et al. 2018;Salvarani et al. 2007;Sasaki et al. 2010;Ellis et al. 2018).
In this case, T. marneffei and A. niger were genetically verified as infectious causes of vasculitis using mNGS and RT-PRC. T. marneffei usually causes invasive fungal infection, characterized by lack of specificity in clinical presentation and difficulties in diagnosis (Chan et al. 2016). A. niger-derived invasive pulmonary aspergillosis is one of the most common mould infections in inpatients (Schmiedel and Zimmerli 2016). Both two strains primarily result in respiratory and bloodstream infections, and few cases have been described in cerebral infection, not to mention the co-infection with T. marneffei (Chan et al. 2016;Schmiedel and Zimmerli 2016).

Conclusion
We first reported the presence of cerebral vasculitis caused by T. marneffei and A. niger in a HIV-positive patient. By summarizing the literature on fungal cerebral vasculitis, the importance of pathogenic identification was further emphasized in the early stage. Briefly, our case highlights the crucial role of mNGS in identification of specific pathogens and provides a new insight into the diagnosis of infectious cerebral vasculitis. Funding The authors did not receive funding for the current work.
Data availability Data supporting the research results of this study can be obtained on request from the corresponding authors Dr. Zhang.

Conflict of interest The authors declare no competing interests.
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