Sarocladium strictum is a fungus belonging to the Ascomycota phylum and the Hypocreales order. It is a prevalent fungus found in the environment, existing in soil, water, plants, and air. While Sarocladium strictum is typically considered a common microorganism in the environment, it can also act as a pathogen for humans and animals. Human infections are known to occur in conditions such as skin diseases, lung infections, and eye infections, although central nervous system infections are exceedingly rare. Due to the rarity of similar cases, there is also a lack of experience in diagnosing it. In order to conduct further research on similar infections, we reviewed 6 cases of S.strictum meningoencephalitis published up to November 2023, focusing on medical history, initial symptoms, diagnostic methods, and treatment. (Table 1)[3-7]
During the literature review process, we observed that patients commonly present with headaches and fever as initial symptoms. The initial examination usually reveals that the CSF and MRI results are similar to other types of meningoencephalitis, so they lack specificity. In summary of past cases, the diagnosis of this disease heavily relied on NGS examination. However, in clinical practice, due to the expensive cost and limited availability of NGS examinations, we rarely conduct NGS examinations on patients in the early stages of treatment. So we recommend early pathogen identification in cases of infection when routine tests fail to determine the pathogen,to save adequate time for subsequent treatment. Due to the rarity of this fungus causing meningoencephalitis and the potential interference of medications in the treatment process, although relevant examinations in this case have suggested the possibility of a fungal infection, but it is difficult to consider it. Therefore, accurately identifying the pathogen is also worth considering. We conducted a summary of the reported cases and found that most of these patients had immune deficiencies or skull base integrity defects. These defects may provide potential infection for S.strictum. In our study of cases in recent years, it has been found that the majority of these patients have a history of exposure to grains and crops. So, we suggest when patients have a high-risk exposure history and similar symptoms, S.strictum should be considered.
In this case, the patient's initial symptoms included headache, fever, and weakness in her left limb at the same time the MRI results revealed abnormal signals in the left cerebellum, midbrain, and cerebral peduncles, as well as in the bilateral basal ganglia regions but no vascular stenosis was identified.(Figure 1, A,a-d) However, the MRI and MRA results revealed the presence of multiple new lesions in the brain after two weeks, multiple vascular narrowing and evident damage are observed. (Figure 1, A, e-h, B, d-f) Considering the patient's symptoms and progressive changes in MRI and MRA results, (Figure 1, A,B) our analysis suggests that the primary mechanism leading to patient mortality is infection-induced vasculitis caused by S.strictum in this case. This also proves that the symptoms of the patient were alleviated after receiving antifungal treatment, but it didn’t save her life. Due to the rarely of relevant cases and research studies, the pathophysiological mechanisms need further investigation.
The most important thing we should focus on treatment. In our review, Amphotericin B, as an antifungal drug, has shown a good therapeutic effect on the treatment of S.strictum. Amphotericin B can effectively alleviate symptoms in patients within a short time.[8]In this case, to decrease nephrotoxicity, we have replaced amphotericin B with amphotericin B colloidal dispersion (ABCD) and achieved comparable outcomes. Unfortunately, Short-term treatment with amphotericin B cannot change results in CSF examination. Based on past cases, our analysis indicates that amphotericin B is an effective agent against most fungi which is often used as the first choice for S.strictum treatment and has shown promising results in cases of pulmonary infection. However, our observation suggests no obvious therapeutic effect for central infections caused by S.strictum. In a previous in vitro study, it was demonstrated that Sarocladium species exhibit high diversity and varying susceptibilities. Specifically, S.strictum was found to be susceptible to voriconazole and terbinafine, but resistant to amphotericin B. [9]After adding fluconazole, a significant improvement was observed in the CSF examination results of our patient in this case. Therefore, we suggest that when the diagnosis is clear, the patient should receive immediate treatment with high-dose, long-term therapy of amphotericin B in combination with voriconazole. In past cases, they also used Ommaya reservoir implantation as an effective treatment method for controlling symptoms.[3] However, it is important to note that effective drug therapy should be the primary choice for treatment. Most importantly, in our case, we further discovered that although the symptoms of the patient were alleviated after receiving antifungal treatment, it didn’t save her life. Through the analysis of MRI results at different times in patients, we have found that antifungal therapy does not prevent the progression of cerebral vasculitis. For this, we hypothesize that S.strictum-induced central nervous system infection may lead to uncontrolled vascular damage. However, the underlying mechanisms remain unclear and we need further research. Therefore, we suggest combining antifungal drugs with anti-vasculitis treatment, which may have a positive effect on the disease.
We have found through the review of relevant literature that the treatment of fungal infections vascular meningoencephalitis has not yet reached a consensus. Corticosteroids have been empirically used in infectious cerebral vasculitides.[10]Some experts recommend oral prednisolone 1 mg/kg per day for 5 days, or methylprednisolone 500 mg per day for 3 days in conjunction with acyclovir to treat varicella zoster virus (VZV) vasculopathy. However, there are no randomized clinical trials to evaluate the beneficial effect of steroids in acute VZV vasculopathy. [11]At the same time, corticosteroid therapy has also shown efficacy in patients with tuberculous meningitis (TBM)-associated vasculitis and neurocysticercosis (NCC)-associated vasculitis. [12, 13]
In this literature, we reported a case of cerebral vasculitis caused by S.strictum infection and provided a review of past cases of S.strictum meningoencephalitis. This case is the first case of cerebral vasculitis caused by S.strictum and we suggest early antifungal therapy should be combined with anti-vasculitis treatment. We hope this finding can offer some help for the treatment of similar patients.