Colitis caused by Entamoeba histolytica identified by real-time-PCR and fluorescence in situ hybridization from formalin-fixed, paraffin-embedded tissue

Abstract

Intestinal amoebiasis in a 35-year-old German patient with a 3 weeks travel history in Indonesia was initially misidentified as non-steroidal anti-inflammatory-drug associated colitis in colonoscopy and histopathological analysis. Furthermore, initial stool examination by microscopy and Entamoeba faecal antigen ELISA did not reveal any protozoan infection. When cessation of non-steroidal anti-inflammatory drug (NSAID) use and mesalazine treatment did not lead to clinical improvement, the patient presented to a specialist for tropical diseases. An intensive reinvestigation including a workup of formalin-fixed, paraffin-embedded colonic biopsies by molecular analysis with real-time PCR and fluorescence in situ hybridization (FISH) proofed the diagnosis of Entamoeba histolytica colitis. Molecular methods including real-time PCR and FISH for the diagnosis of amoebiasis from histopathological samples are rarely used for the diagnosis of E. histolytica infections. Bloody diarrhoea vanished after the onset of metronidazole treatment. In conclusion, the here-presented case demonstrates how modern molecular diagnostics may help to diagnose E. histolytica-associated colitis, even from difficult specimens like paraffin-embedded, formalin-fixed tissue.

Protozoan Infections Acquired from Food or Drinking Water: An Update

“…The identified sources of the infection cases and outbreaks most recently reported for waterborne and foodborne parasitic protozoans are shown in Table 1. [8,9,19,35,36,45,47,64,66,68,69,72,110,125,126,132,133,146,151,152,162,[169][170][171][172][173]178,185,186,199,200,205,207,209,211,218,220,221,228,254,255,262].…”

“…The patient did not improve with the appropriate therapy so reinvestigation was carried out by examining colon biopsies by real-time PCR and fluorescence in situ hybridization (FISH) that proved the diagnosis of E. histolytica infection. Metronidazole therapy allowed the patient's recovery [45].…”

“…To increase the sensitivity, microscopical examination must be carried out for at least 3 stool samples collected over a 10-day period and PCR should also be performed. Other techniques that were used for protozoan infection diagnosis or detection are immunoassays, such as enzyme linked immunosorbent assay (ELISA), enzymatic immunoassays (EIA), rapid immunochromatographic tests and immunofluorescence assays [8,17,28,[41][42][43][44][45][46][47][48][49][50][51], and molecular genotyping methods specific for each organism in most investigations.…”

Food and Drinking Water as Sources of Pathogenic Protozoans: An Update

“…For a 35-year-old German patient who had recently traveled to Indonesia, E. histolytica infection was initially misidentified as colitis associated with non-steroidal anti-inflammatory drug use because initial stool examination by microscopy and Entamoeba fecal antigen ELISA did not reveal the infection. The patient did not improve with the therapy, so reinvestigation was carried out on colon biopsies using real-time PCR and fluorescence in situ hybridization (FISH) that revealed E. histolytica infection [201]. These cases indicated the need to suspect E. histolytica infection if a patient does not respond to immunosuppression.…”

“…Moreover, a greater prevalence of amoebiasis was observed in patients with IBD (16%), compared to the normal population (1.7%), so the amoebic infection should be ruled out in IBD patients before the administration of corticosteroids [193]. The mentioned cases of Crohn's disease misdiagnosis, except the fatal one, were successfully treated with metronidazole with or without paromomycin [200,201].…”