Figure 2.

(A) Brain biopsy sections of the same patient stained with hematoxylin and eosin showing a dense granulomatous infiltrate accompanied by microorganisms morphologically consistent with free-living amoeba (arrow). (B) Higher magnification of (A) showing the characteristic nuclear appearance of the amoeba. (C) Indirect immunofluorescence labeling of brain biopsy sections performed using a rabbit serum (1:100, R150, exposed to Acanthamoeba castellanii whole-cell lysate) followed by 1:200 fluorescein isothiocyanate-conjugate goat anti-rabbit immunoglobulin G (F6005; Sigma-Aldrich): at low magnification, the photomicrograph shows fluorescent microorganisms around blood vessels. (D) High magnification photomicrograph showing 2 Acanthamoebae fluorescing bright green after indirect immunofluorescence.