Keywords: Cladophialophora bantiana; Brain abscess; Renal transplant; Molecular characterization

Background

Primary cerebral phaeohyphomycosis is a rare infection caused by darkly pigmented fungi, called as dematiaceous moulds with melanized cell wall, which carry a high mortality rate up to 70% [1-3]. In a review of cases of primary central nervous system phaeohyphomycosis, the most frequently isolated species was Cladophialophora bantiana (48%) and the next most frequent isolate was Ramichloridium mackenziei (13%) [2,4]. Cladophialophora bantiana is strikingly neurotropic, ubiquitously present in soil, prefers warmer climate with high humidity and distributed widely (Asia, North and South America, Europe, Africa) [1,5,6]. Though its propensity for nervous tissue is not fully understood, a possible mechanism involves melanin production which interferes with microbial recognition, scavenges free radicals and prevents eradication of fungi from brain parenchymal tissue [7,8].

Brain abscesses caused by C. bantiana have been reported in both immunocompetent and immunocompromised patients, while more than half of the cases are seen in immunocompetent males [3,9]. It poses a diagnostic dilemma due to non specific clinical presentation, neuroimaging findings mimicking a space occupying lesion and relative rarity of this condition, causing a delay in diagnosis which results in fatal outcome inspite of aggressive surgical and antifungal therapy [9-11]. Laboratory-based investigations play a vital role in the diagnosis and management of such dreadful infections [11].

Here we present a case of cerebral Cladophialophora infection, an incidental finding in a renal transplant recipient.

Case presentation

A 30-year-old male with pre-existing chronic kidney disease since 2-3 years and dependent on regular dialysis, presented to our institution for a planned renal transplantation and underwent the same on 15^th February 2023.During the post-operative period he was put on immunosuppressants. After an early uneventful post-operative period, on 17^th post-operative day, he developed a mild headache to begin with which increased in severity over few hours,not associated with fever, nausea or vomiting. After few hours, patient became drowsy and developed left sided hemiparesis, for which neurosurgery consultation was called upon.

On physical examination, patient was afebrile, pupils were bilaterally reactive. Glasgow coma scale (GCS) score was reduced at 10/15 (E3/V2/M5). Power in left upper and lower limb was reduced (3/5). Computed tomography (CT) scan of head was advised, which revealed presence of an ill-defined hypodense lesion with hypodense rim in right fronto-parietal lobe with severe perilesional edema, midline shift and mild obstructive hydrocephalus giving a picture of cerebritis with abscess formation (Figure 1). To know the extent of soft tissue lesion, magnetic resonance imaging (MRI) of head was performed, which revealed presence of multiple coalesced abscesses in right fronto-parietal lobe with abundant perilesional edema, causing a mass effect on ventricle. Complete blood count showed leukocytosis with raised polymorphonuclear leukocytes (91.8%).

Figure 1: CT Head showing hypodense lesion in rt. fronto-parietal lobe.

Patient was started on empirical antibiotic coverage (Meropenem) and neuro-navigation guided aspiration of abscess was done yielding 15ml of purulent material which was sent for microbiological investigations. Gram stain showed presence of thin (6-8µm), septate, sparsely branched fungal hyphae, which was immediately conveyed to the attending clinician and patient was started on intravenous liposomal amphotericin B (Figure 2). No acid fast bacilli were observed on Zeihl Neelsen staining of aspirate and similar hyphal elements were observed as on gram stain. Potassium hydroxide (KOH) mount of abscess material revealed presence of thin, hyaline, septate, sparsely branched (Figure 3).