Case report: multiple and atypical amoebic cerebral abscesses resistant to treatment

Abstract

Background: The parasite Entamoeba histolytica is the causal agent of amoebiasis, a worldwide emerging disease. Amebic brain abscess is a form of invasive amebiasis that is both rare and frequently lethal. This condition always begins with the infection of the colon by E. histolytica trophozoites, which subsequently travel through the bloodstream to extraintestinal tissues.

Case presentation: We report a case of a 71-year-old female who reported an altered state of consciousness, disorientation, sleepiness and memory loss. She had no history of hepatic or intestinal amoebiasis. A preliminary diagnosis of colloidal vesicular phase neurocysticercosis was made based on nuclear magnetic resonance imaging (NMRI). A postsurgery immunofluorescence study was positive for the 140 kDa fibronectin receptor of E. histolytica, although a serum analysis by ELISA was negative for IgG antibodies against this parasite. A specific E. histolytica 128 bp rRNA gene was identified by PCR in biopsy tissue. The final diagnosis was cerebral amoebiasis. The patient underwent neurosurgery to eliminate amoebic abscesses and was then given a regimen of metronidazole, ceftriaxone and dexamethasone for 4 weeks after the neurosurgery. However, a rapid decline in her condition led to death.

Conclusions: The present case of an individual with a rare form of cerebral amoebiasis highlights the importance of performing immunofluorescence, NMRI and PCR if a patient has brain abscess and a poorly defined diagnosis. Moreover, the administration of corticosteroids to such patients can often lead to a rapid decline in their condition.

Keywords: 140 kDa fibronectin receptor; Brain abscess; Cerebral amoebiasis; Entamoeba histolytica; NMRI; PCR.

Fig. 1

Cranial nuclear magnetic resonance image. A. Multiple cystic lesions with ring enhancement after contrast administration, without restricted diffusion, in temporal and occipital lobes. (a) Axial T1SE, (b) Axial T2 Propeller, (c) Axial T1 SE + gadolinium, (d) Axial DWI. B. Gadolinium contrast brain NMRI showing ring-enhanced lesions with multilobar distribution. (a) and (b) Sagittal T1 SE + gadolinium, (c) coronal T1 SE + gadolinium with supra- and infratentorial lesions, (d) coronal T1 SE + gadolinium with temporal and intraventricular lesions

Fig. 2

E. histolytica trophozoites are revealed in amoebic brain abscesses by histopathological study. A broad area of necrotic nerve tissue can be observed. Trophozoites are widely distributed in the abscess (red arrow), as illustrated by the light microscopic images (X50). An amoebic trophozoite is shown with H&E staining (box in the upper right corner, X400)

Fig. 3

Immunodetection of E. histolytica trophozoites in brain tissue by immunohistochemistry and immunofluorescence. Identification of the E. histolytica 140 kDa fibronectin (FN)-binding protein (EhFNR) and glial fibrillary acidic protein (GFAP) in brain tissue by immunofluorescence. a Amoebic trophozoites stained using peroxidase-labeled rabbit anti-E. histolytica polyclonal antibody (X 1000). b E. histolytica actin cytoskeleton dynamics and distribution in amebic brain abscesses. Actin was stained with rhodamine-phalloidin (1:40, red), forming plate adhesions, as shown by the yellow arrow (X 400). c E. histolytica trophozoites stained positive for EhFNR (red), GFAP (green) and nuclei (Hoechst 1:1000, blue) in amebic brain abscess tissue (X400). d GFAP-immunoreactive cells in brain sections (green) and nuclei (blue) (X400)

Fig. 4

PCR, cloning and sequencing. Total DNA was extracted from 100 mg paraffin-embedded cerebral tissue using the Wizard Genomic DNA purification kit (Promega, Madison, WI, USA). DNA was quantified in a NanoDrop 2000 (Thermo Scientific, Waltham, MA, USA), obtaining an E. histolytica 128 bp amplicon for the rRNA gene, which was cloned with the CloneJET PCR Cloning Kit (Thermo Scientific) using a pJET1.2/blunt cloning vector. Then, the ligation mixture was used for transformation of Escherichia coli DH5a calcium-competent cells. Plasmid DNA was extracted from heat-shocked cells with the Zyppy Plasmid Miniprep (Zymo Research, Irvine, CA, USA). Clones were analyzed by PCR to verify the insertion of the amplicon into the pJET1.2/blunt vector. The plasmid sequence shows forward and reverse primers (electropherograms) that correspond to the E. histolytica rRNA gene sequence. Hu = 120 bp amplicon for human β-actin; M = bp marker; Eh = 128 bp amplicon for the E. histolytica rRNA 18 s gene, NTC = no template control

Fig. 5

ELISA. a The ELISA plate displays a slight reaction to a negative control (1, 1: 5000; 2, 1: 10000). The positive reaction is evident from the application of anti-E. histolytica antibodies to the serum of an individual with amoebic liver abscess (3, 1: 5000; 4, 1: 10000). There was a negative reaction to anti-E. histolytica antibodies in the serum of the patient under study despite the presence of brain abscesses (5, 1: 5000; 6, 1: 10000). b The graph shows the significant difference between the positive control (1:5000) and the patient in the current case study (1:5000) (***) ANOVA