Renal microsporidiosis due to Encephalitozoon cuniculi in an HIV/AIDS patient with persistent fever and kidney injury
Authors: Matteo Augello, Francesca Bai, Andrea Galassi, Valeria Bono, Alessia Moro, Luca Carsana, Cristina Tonello, Antonella Tosoni, Manuela Nebuloni, Antonella d’Arminio Monforte, Giulia Marchetti
Journal: Clinical Microbiology and Infection (2021)

A 44-year-old Filipino man recently diagnosed with HIV infection presented to our clinic complaining of fever and asthenia for a few days. Virological and immunological parameters displayed a severe immunodepression (CD4+ T lymphocytes: 2/μL, 0%) with an HIV viraemia of 80 141 copies/mL.Despite the effective treatment of a disseminated cytomegalovirus infection and oesophageal candidiasis, with subsequent initiation of cART (bictegravir/emtricitabine/tenofovir alafenamide, BIC/FTC/TAF) the patient was persistently feverish with at least three episodes per day. An abdomen contrast CT scan displayed faded hypodense renal alterations of uncertain meaning (Fig. 1A). A subsequent total-body PET/CT showed increased glucose metabolism in both kidneys (Fig. 1B). Meanwhile the patient developed a progressive renal impairment with a rise in creatinine values up to 220 μmol/L.An ultrasound-guided renal biopsy was then performed. Histological examination with haematoxylin–eosin (H&E) staining highlighted necrotizing granulomatous interstitial inflammation with numerous 1-μm corpuscles within granulomas and tubular cells (Fig. 1C). Similar particles were also detected in fresh urine on examination by light microscopy (Fig. 1D). Analyses of renal biopsy showed spores and proliferative forms of microsporidia within intracellular parasitophorous vacuoles in scattered tubular cells (Fig. 1E) and in glomerular mesangial cells (Fig. 1F), with morphological characters compatible with Encephalitozoon, including elongated spores (about 1–1.5 by 2–3 μm), a polar tube arranged within the spore in a single row with 4–6 coils (Fig. 1G), and round to elongated proliferative forms with isolated heterochromatic nuclei (Fig. 1E,F) [[1]Weber R. Schwartz D.A. Deplazes P. Laboratory diagnosis of microsporidiosis.in: Wittner Murray The microsporidia and microsporidiosis. ASM Press, Washington DC1999: 315-362Crossref Google Scholar].PCR for the detection of microsporidia DNA in both urine specimens and formalin-fixed, paraffin-embedded (FFPE) renal tissue was performed, confirming the diagnosis of renal encephalitozoonosis (Fig. 1H).Successive Sanger sequencing of the microsporidial DNA amplicon obtained from FFPE tissues (BigDye™ Terminator v3.1 Cycle Sequencing Kit, Applied Biosystem) was performed. The DNA sequence was then compared to the public DNA databases by using the BLAST interface (http://www.ncbi.nlm.nih.gov/BLAST/) and proved to be 99% identical to previously reported Encephalitozoon cuniculi sequences.Treatment with oral albendazole 400 mg twice daily was therefore started; a progressive improvement of the fever curve and a slow reduction in serum creatinine were at last observed, so the patient could be discharged after more than 2 months of hospitalization.Author contributionsMA wrote the report. FB, VB, Ad'AM and GM reviewed the manuscript. MA, FB, Ad'AM and GM were involved in the clinical care of the patient. AG performed renal biopsy. AM, LC, CT, AT and MN were responsible for the microscopic and molecular diagnostics.Transparency declarationThe authors declare that they have no conflicts of interest. No specific funding was received for this work. A 44-year-old Filipino man recently diagnosed with HIV infection presented to our clinic complaining of fever and asthenia for a few days. Virological and immunological parameters displayed a severe immunodepression (CD4+ T lymphocytes: 2/μL, 0%) with an HIV viraemia of 80 141 copies/mL. Despite the effective treatment of a disseminated cytomegalovirus infection and oesophageal candidiasis, with subsequent initiation of cART (bictegravir/emtricitabine/tenofovir alafenamide, BIC/FTC/TAF) the patient was persistently feverish with at least three episodes per day. An abdomen contrast CT scan displayed faded hypodense renal alterations of uncertain meaning (Fig. 1A). A subsequent total-body PET/CT showed increased glucose metabolism in both kidneys (Fig. 1B). Meanwhile the patient developed a progressive renal impairment with a rise in creatinine values up to 220 μmol/L. An ultrasound-guided renal biopsy was then performed. Histological examination with haematoxylin–eosin (H&E) staining highlighted necrotizing granulomatous interstitial inflammation with numerous 1-μm corpuscles within granulomas and tubular cells (Fig. 1C). Similar particles were also detected in fresh urine on examination by light microscopy (Fig. 1D). Analyses of renal biopsy showed spores and proliferative forms of microsporidia within intracellular parasitophorous vacuoles in scattered tubular cells (Fig. 1E) and in glomerular mesangial cells (Fig. 1F), with morphological characters compatible with Encephalitozoon, including elongated spores (about 1–1.5 by 2–3 μm), a polar tube arranged within the spore in a single row with 4–6 coils (Fig. 1G), and round to elongated proliferative forms with isolated heterochromatic nuclei (Fig. 1E,F) [[1]Weber R. Schwartz D.A. Deplazes P. Laboratory diagnosis of microsporidiosis.in: Wittner Murray The microsporidia and microsporidiosis. ASM Press, Washington DC1999: 315-362Crossref Google Scholar]. PCR for the detection of microsporidia DNA in both urine specimens and formalin-fixed, paraffin-embedded (FFPE) renal tissue was performed, confirming the diagnosis of renal encephalitozoonosis (Fig. 1H). Successive Sanger sequencing of the microsporidial DNA amplicon obtained from FFPE tissues (BigDye™ Terminator v3.1 Cycle Sequencing Kit, Applied Biosystem) was performed. The DNA sequence was then compared to the public DNA databases by using the BLAST interface (http://www.ncbi.nlm.nih.gov/BLAST/) and proved to be 99% identical to previously reported Encephalitozoon cuniculi sequences. Treatment with oral albendazole 400 mg twice daily was therefore started; a progressive improvement of the fever curve and a slow reduction in serum creatinine were at last observed, so the patient could be discharged after more than 2 months of hospitalization. Author contributionsMA wrote the report. FB, VB, Ad'AM and GM reviewed the manuscript. MA, FB, Ad'AM and GM were involved in the clinical care of the patient. AG performed renal biopsy. AM, LC, CT, AT and MN were responsible for the microscopic and molecular diagnostics. MA wrote the report. FB, VB, Ad'AM and GM reviewed the manuscript. MA, FB, Ad'AM and GM were involved in the clinical care of the patient. AG performed renal biopsy. AM, LC, CT, AT and MN were responsible for the microscopic and molecular diagnostics. Transparency declarationThe authors declare that they have no conflicts of interest. No specific funding was received for this work. The authors declare that they have no conflicts of interest. No specific funding was received for this work. We are grateful to the patient and his family who trusted in our work and kindly agreed to the publication of these pictures and the case report. We also thank all the physicians who helped us to finally reach this complex diagnosis, allowing us to treat the patient properly, and all other health professionals who daily cared for him.