Molecular Characterisation of Cladophialophora species Isolated from Brain Abscess in a Renal Transplant Recipient
by Babita Kumari Fageria1, Siva Prasad Reddy Basava1, Mehvish Khan2, Pratik Tripathi2, Sanjeev Attry3, Vijay Gupta3, Abhijit Verma3, Puneet Bansal3, Madhu Mali1, Shama Tomar1, Rama Chaudhry1*
1Department of Microbiology/ National Institute of Medical Sciences & Research, Jaipur, Rajasthan, India 2Department of Nephrology/ National Institute of Medical Sciences & Research, Jaipur, Rajasthan, India
3Department of Neurosurgery/ National Institute of Medical Sciences & Research, Jaipur, Rajasthan, India
*Corresponding author: Rama Chaudhry, Department of Microbiology/ National Institute of Medical Sciences & Research, Jaipur, Rajasthan, India
Received Date: 4 September 2023
Accepted Date: 19 September 2023
Published Date: 22 September 2023
Citation: Fageria BK, Basava SPR, Khan M, Tripathi P, Attry S, et al., (2023) Molecular Characterisation of Cladophialophora species Isolated from Brain Abscess in a Renal Transplant Recipient. Infect Dis Diag Treat 7: 233. https://doi.org/10.29011/2577-1515.100233
Background: Though rare, primary central nervous system infection by melanized fungus Cladophialophora, is highly fatal inspite of surgical and medical intervention, posing a diagnostic dilemma, resulting in diagnostic delay, which adds to the poor outcome. Cladophialophora, being strikingly neurotropic, infects both immunocompetent and immunocompromised hosts, being more common in immunocompetent males. Among immunocompromised hosts, predominantly transplant recipients are affected. A case of brain abscess by Cladophialophoraas an incidental finding in renal transplant recipient from western India is presented here. Case presentation: A 30 year old male, known case of chronic kidney disease, underwent renal transplantation. During post-transplantation period developed insidious onset headache and left-sided hemiparesis. CT and MRI imaging of head revealed presence of multiple coalesced abscesses and pus aspirate on direct microscopy revealed presence of septate filamentous fungi which was confirmed by fungal culture and a presumptive identification of Cladophialophora bantiana was made based on morphological characteristics. On definitive identification by ITS sequencing, microbe was found to be Cladophialophora bantiana strain IEC-CBM06 internal transcribed spacer 1; 5.8S ribosomal RNA gene. Patient responded well to appropriate surgical intervention and systemic antifungal therapy and is on regular follow up. Discussion & Conclusion: CNS infections by this neurotropic mould, which are usually fatal, should be taken into consideration for differential diagnosis of cerebral abscess in both immunocompetent and immunocompromised patients, as they are increasingly recognized, and timely diagnosis and prompt intervention is a good predictor of survival. Molecular identification plays a vital role in providing a timely and accurate laboratory diagnosis.x
Keywords: Cladophialophora bantiana; Brain abscess; Renal transplant; Molecular characterization
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 .
Here we present a case of cerebral Cladophialophora infection, an incidental finding in a renal transplant recipient.
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 15th February 2023.During the post-operative period he was put on immunosuppressants. After an early uneventful post-operative period, on 17th 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).
Figure 2: Gram stain of aspirate showing gram positive, thin, septate, sparsely branched fungal hyphae.
Figure 3: KOH mount of aspirate revealing thin, septate, sparsely branched hyphae.
Aerobic bacterial cultures were performed using Blood agar and MacConkey agar which remained sterile after 48 hours of incubation. Fungal culture was put on 4% Sabouraud’s dextrose agar (SDA) with and without cycloheximide and incubated at 25℃ and 37℃. Fungal growth appeared on SDA after 72 hours of incubation, initially small, only at the point of inoculation which was indicative of a phaeoid (pigmented) filamentous fungus and the same was communicated to clinician, following which voriconazole was added to the treatment regimen.
After 12 days of incubation, SDA showed an olivaceous greyish velvety fungal growth on obverse with a black reverse, both at 25℃ and 37℃ (Figure 4). Lactophenol cotton blue (LPCB) mount of the growth showed presence of brownish walled, oval to ellipsoidal single-celled conidia in chains, arising from undifferentiated rarely branching conidiophores (Figure 5). Depending upon macroscopic and microscopic morphological characteristics it was presumptively identified as Cladophialophora bantiana. It was tested for urea hydrolysis which turned out to be positive. For definitive species identification by ITS sequencing, isolate was sent to Biokart India Pvt. Ltd. It was performed using ITS forward primer ‘TCCGTAGGTGAACCTGCGG’ and ITS reverse primer ‘TCCTCCGCTTATTGATATGC’. The Microbe was found to be Cladophialophora bantiana strain IEC-CBM06 internal transcribed spacer 1; 5.8S ribosomal RNA gene, which showed 100% match on analysis by basic local alignment search tool (BLAST) (Figure 6).