A Fatal Case of Naegleria fowleri Meningoencephalitis in Taiwan
A 75-year-old man presented to a local hospital complaining of headache, fever, and right arm myoclonic seizures. He had mild leukocytosis; however, there was no indication of intracerebral hemorrhage or other obvious abnormalities. He was transferred to Chung Shan Medical University Hospital (Taichung, Taiwan) due to sudden onset of convulsion and right side limbs weakness. The neurologist diagnosed a CNS infection and seizure of unknown etiology and admitted the patient to Coronary Care Unit for further evaluation and treatment.\nLaboratory studies showed a total leukocyte count of 12,190/µl (with 94.6% neutrophils, 3.0% lymphocytes, and 2.2% monocytes), and a platelet count of 148,000/µl. The clinical biochemistry data showed blood urea nitrogen at 22.48 mg/dl, a blood sugar (ac) level of 175 mg/dl, a blood sugar (pc) level of 255 mg/dl, and C-reactive protein level of 2.85 mg/dl. The serologic result for HIV was negative. Blood cultures of bacteria and fungi were negative. Magnetic resonance (MR) imaging of the patient's brain showed that sagittal and axial post-gadolinium T1-weighted images revealed diffuse leptomeningeal enhancement along the brain surface, including the brainstem, frontal lobe, and cerebellum. A contrast-enhanced computed tomography (CT) scan showed diffuse leptomeningeal enhancement and subarachnoid and intraventricular hemorrhages.\nA lumbar puncture was performed and showed slightly-turbid cerebrospinal fluid (CSF) with 4 mg/dl glucose, 954.1 mg/dl protein, and a leukocyte count of 560/µl with 90.5% neutrophils, 5.0% lymphocytes, and 4.5% monocytes. India ink preparations, acid-fast stains and Gram stains for bacteria and fungi were all negative. The CSF was negative for viral detection. Also, CSF cultures for bacteria and fungi were negative.\nA wet-mount CSF smear revealed numerous trophozoites of approximately 10-25 µm size, which moved rapidly and directionally by pseudopodia. The cytoplasm of the trophozoites contained granular, abundant vacuoles. The amoeba was identified as N. fowleri (). A cytospin preparation was used to examine the CSF and the CSF sediment preparations were fixed with Liu's stain, which revealed amoebae containing nuclei and numerous cytoplasmic vacuoles (). N. fowleri infection was diagnosed and intravenous amphotericin B (50 mg q.d.) was started.\nThe CSF specimen obtained during hospitalization was examined at the Centers for Disease Control (CDC) of Taiwan. N. fowleri infection was confirmed by PCR analysis using the primers Nae3-F (5'-CAA ACA CCG TTA TGA CAG GG-3') and Nae3-R (5'-CTG GTT TCC CTC ACC TTA CG-3') to amplify fragments of a 183-bp product []. For the detection of Acanthamoeba spp., primers AcantF900 (5'-CCC AGA TCG TTT ACC GTG AA-3') and AcantR1100 (5'-TAA ATA TTA ATG CCC CCA ACT ATC C-3') were used to amplify fragments of a 180 bp product []. N. fowleri Carter strain (American Type Culture Collection; ATCC no. 22758, Manassas, Virginia, USA) and A. castellanii Neff strain (ATCC 30010) were used as positive controls. The PCR products () were visualized after electrophoresis on 2% agarose gels, where only a 183 bp amplicon of Naegleria spp. was detected in the CSF specimen, but no band for Acanthamoeba spp. was detected. For further confirmation, the PCR product was subjected to DNA sequencing to identify the species. The 183 bp PCR product showing higher similarity percentage to N. fowleri using the BLAST algorithm at the National Center for Biotechnology Information (NCBI) website (). Although amphotericin B treatment was started immediately, the patient fell into coma. After 21 days of hospitalization, his health condition showed unstable hemodynamics and brain death. At 25 days post-treatment (beginning of treatment), the patient sustained to suffer from severe shock, followed by PAM and multiple organ failure leading to the patient's death.