Fatal Donor-Derived Disseminated Acanthamoeba Infection in a Liver Transplant Recipient

Abstract

Acanthamoeba spp. was determined to be the cause of illness after an adult liver transplant recipient died from rapidly progressive encephalitis. Upon autopsy, amebae were identified in multiple organs, including the transplanted liver. The donor had history of kidney transplantation and died of encephalitis presumed to be due to toxoplasmosis. Acanthamoeba was identified in donor brain tissue by indirect immunofluorescence assay. Clinicians assessing prospective solid organ donors with encephalitis should consider Acanthamoeba infection.

Acanthamoeba is a genus of free-living ameba that has been detected in household tap water, soil, natural freshwater bodies, ventilation ducts, and other environmental niches [1, 2]. It is known to cause rare, severe infections of the central nervous system (CNS), skin, sinuses, and other organ systems, primarily among immunocompromised hosts [3]. Infections with Acanthamoeba spp. are most often fatal, particularly when manifesting as granulomatous amebic encephalitis (GAE). The proposed mode of transmission for GAE is inhalation of cysts or direct skin inoculation, followed by hematogenous spread [1]. Human exposure to Acanthamoeba spp. is likely a common event, as healthy individuals have demonstrated antibodies against this pathogen [4, 5]. However, most do not become infected. Immunosuppressed hosts are particularly susceptible to Acanthamoeba spp., and it has been defined as a primarily opportunistic pathogen since the advent of the HIV epidemic in the 1980s [6–8]. In most cases, the exposure to Acanthamoeba cannot be clearly identified. Although Acanthamoeba infections have been diagnosed in both solid organ and hematopoietic stem cell transplant recipients in the United States, a definitive link to an infected donor has not previously been described. Here, we describe 2 cases of GAE diagnosed in a liver transplant recipient and the immunosuppressed host.

CASE DESCRIPTIONS

Patient 1: Liver Recipient

A 57-year-old man with history of liver cirrhosis and hepatocellular carcinoma due to hepatitis C and alcoholic liver disease underwent living donor liver transplantation. Induction therapy consisted of methylprednisolone and maintenance immunosuppression of tacrolimus, mycophenolate, and prednisone. On day 4 following transplantation, his course was complicated by a biliary leak, disruption of the hepatico-jejunostomy and hepatic artery thrombosis for which he underwent thrombectomy. On day 7, he required emergent surgery for hemoperitoneum and hemorrhagic shock. He developed sepsis secondary to vancomycin-resistant Enterococcus bacteremia and acute oliguric renal failure. His allograft was not viable, and he was emergently re-listed for liver transplantation.

On day 14, the patient underwent deceased donor liver transplantation. Posttransplantation, the recipient was started on pyrimethamine, clindamycin, folinic acid, and oral atovaquone due to reported cerebral toxoplasmosis as the cause of donor death. On day 8 posttransplantation, he was noted to be agitated and aggressive. Subsequently, he developed altered mental status, twitching of his arms, and rapid eye blinking concerning for seizures. Over the following 48 hours, the patient continued to decompensate requiring vasopressor support. Blood was sent for Toxoplasma polymerase chain reaction (PCR) and microbial cell-free DNA metagenomic sequencing (Karius Test®).

On day 10 posttransplantation, brain magnetic resonance imaging identified numerous foci of both cortices and more rounded central diffusion restriction involving multiple cerebral cortices as well as the periventricular white matter, deep gray nuclei, and brainstem, suggestive of hemorrhagic encephalitis. Lumbar puncture was performed, and cerebrospinal fluid (CSF) analysis revealed protein 464 mg/dL, glucose 93 mg/dL, and 67 white blood cells/µL (90% neutrophils and 10% monocytes). A CSF meningitis and encephalitis pathogen PCR panel and a Cryptococcus antigen test were negative. The patient ultimately developed brain death. Postmortem, Toxoplasma PCR performed on blood and CSF were negative, while the plasma cell-free DNA metagenomic sequencing and CSF PCR (University of Washington) were positive for Acanthamoeba.

Postmortem pathologic examination revealed evidence of disseminated Acanthamoeba infection. Amebae were visualized throughout the brain, spinal cord, and multiple organs (Figure 1). Notably, multifocal abscesses containing both trophozoites and cysts were identified throughout the transplanted liver, and the hepatic sinusoids and vessels contained numerous amebae. Amebae were also identified in the lungs, pancreas, esophagus, intestines, pituitary gland, adrenal gland, parathyroid glands, lymph nodes, spleen, and testicles.

Figure 1.

Histopathology images from various organs examined upon autopsy from liver recipient. A, Amebic trophozoites destroying normal architecture of spinal cord tissue. B, Amebic perivascular infiltrates in the medulla. C, Trophozoites in the transplanted liver with abscess, necrosis, and disruption of normal parenchyma (medium power). D, Amebic infiltration of transplanted liver (high power). Black arrows: trophozoites.

Patient 2: Liver Donor

A 43-year-old woman with end-stage renal disease secondary to Goodpasture syndrome and kidney transplant 3 years previously was admitted with altered mental status. Her maintenance immunosuppressive regimen included tacrolimus, prednisone, and mycophenolate mofetil. A stereotactic brain biopsy was performed due to abnormalities seen on brain imaging and demonstrated necrotizing cerebritis with cysts and trophozoites. Histopathology and immunohistochemistry initially supported a diagnosis of cerebral toxoplasmosis. She was treated with high-dose trimethoprim–sulfamethoxazole; however, her condition rapidly deteriorated, and she progressed to brain death within 4 days of presentation. After standard organ donor evaluation processes, the liver was recovered for transplantation. Postrecovery, Toxoplasma CSF PCR and Toxoplasma IgG and IgM antibody testing were reported as negative.

When Acanthamoeba infection was diagnosed in the deceased liver recipient, formalin-fixed, paraffin-embedded (FFPE) donor brain tissue was sent to the Free-Living and Intestinal Ameba Laboratory at the Centers for Disease Control and Prevention (CDC). Indirect immunofluorescence (IIF) confirmed the presence of Acanthamoeba. Species-level identification and genotyping of Acanthamoeba was not conducted due to limitations in the available specimens. Formalin-fixed, paraffin-embedded tissue, which was the only donor specimen available, is not suitable for molecular detection and genotyping. It is also challenging to determine species from FFPE tissue using IIF methods, as species-defining cysts may not always be visualized. However, the rarity of the infection, the clinical presentations of the patients, the temporal relatedness of the cases, and involvement of the transplanted organ provide evidence that this infection was donor derived.

This investigation was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy (see, eg, 45 C.F.R. part 46.102(I)(2), 21 C.F.R. part 56; 42 U.S.C. §241(d); 5 U.S.C. §552a; 44 U.S.C. §3501 et seq).

DISCUSSION

Nonkeratitis Acanthamoeba infections are diagnosed and reported in 0–12 people annually in the United States, with most cases occurring in immunocompromised patients [3, 9]. In a review of cases between 1965 and 2020, 18% of cases occurred in patients with a history of solid organ transplantation [3]. While Balamuthia mandrillaris, another free-living ameba, has been transmitted through organ transplantation, Acanthamoeba has not been definitively determined to have been derived from a donor [10, 11]. Rather, most cases have occurred subsequent to prolonged immunosuppression following transplantation. This report demonstrates what has long been suspected—that Acanthamoeba can be transmitted through solid organ transplantation.

Of all known solid organ transplant recipients who have been infected with Acanthamoeba in the United States, the majority (17) were kidney recipients; only 1 was a liver recipient [3, 12]. Transplant recipients have developed various disease presentations including GAE, cutaneous disease, rhinosinusitis, pulmonary disease, osteomyelitis, and disseminated disease. Both patients in this case report developed GAE and ultimately died due to CNS impairment, but evidence of Acanthamoeba was found in other organ systems as well, including the transplanted liver, suggesting that dissemination occurred.

Granulomatous amebic encephalitis most often causes altered mental status and occasionally focal neurologic deficits and can progress slowly or rapidly [8]. Brain lesions are typically seen on imaging [8]. In some cases of GAE, skin lesions may precede CNS symptoms, appearing as multiple nodules or papules that can progress to ulcers and eschars [2]. Rhinosinusitis, pulmonary disease, osteomyelitis, or infections of other organ systems may also occur [3]. Granulomatous amebic encephalitis is most commonly diagnosed by detecting Acanthamoeba in brain tissue by PCR, IIF, or immunohistochemical staining. However, Acanthamoeba has also been detected in CSF by PCR or metagenomic sequencing methods [13]. Treatment of Acanthamoeba infections includes a multidrug regimen, but outcomes remain poor [14]. There is no recommended prophylactic regimen.

These cases illustrate the importance of considering Acanthamoeba when accepting a solid organ from an immunosuppressed host with encephalitis or other brain lesions. Though rare, Acanthamoeba can cause devastating, often fatal infections that can be transmitted through organ transplantation. Clinicians caring for patients with suspected free-living ameba infections can contact the CDC free-living ameba clinical consultation service at (770) 488–7100 [14].