Two cases of endoscopically diagnosed amebic colitis treated with paromomycin monotherapy

Abstract

Patient 1 who was a 43-year-old male was first referred to our institute because of an allergic reaction to metronidazole with oral mucosal erosions during his sixth treatment for amebic colitis. He had a history of 5 recurrent episodes of amebic colitis (last treatment was 3 years earlier, using metronidazole followed by paromomycin) (S1 Table). Besides oral mucosal erosions, he complained of soft or loose stools 2 to 3 times daily without abdominal pain or fever. Although we proposed admission for close observation during his treatment, he selected outpatient treatment at a nearby hospital. Three months later, the patient returned to our hospital because his wife was also diagnosed with Entamoeba histolytica infection. The couple operated a Japanese inn in a suburban area of Tokyo. They had no travel history to developing countries within the past 10 years. He denied extramarital sexual intercourse and oral-anal sexual contact. He did not have any past histories, except for recurrent amebiasis. There were no reported outbreaks of gastrointestinal diseases for over 10 years in the couple's residential area. Results of a blood examination showed no particular abnormalities (Table 1). Although a direct microscopic examination was negative for any protozoa, the patient's stool tested positive for E. histolytica with polymerase chain reaction (PCR). Total colonoscopy showed white-coated ulcerative lesions at the cecum (Fig 1A). In a pathological examination, Entamoeba was identified on the surface mucosa in a biopsy sample (S1 Fig).We treated the patient with a lumen-active agent (paromomycin monotherapy) because (1) he had a past history of acute oral mucosal lesions owing to metronidazole, (2) tinidazole is not approved to treat amebiasis in Japan, and (3) his symptoms of E. histolytica were mild. Negative PCR results for E. histolytica were confirmed in stool samples taken at 1, 2, and 4 months after treatment. Follow-up colonoscopy showed that lesions of the cecum were completely resolved ( Fig 1C).Patient 2 was a 43-year-old female and the wife of patient 1. She was referred to our institute because of Entamoeba infection as confirmed on microscopic examination of a stool sample. One month before diagnosis, she had a positive fecal occult blood test result in an advanced health check. Dysentery, abdominal pain, and fever were not documented at referral. She denied extramarital sexual intercourse. She had a high anti-E. histolytica antibody titer (1:800). Direct microscopy of stool samples showed the cystic form of Entamoeba. E. histolytica was confirmed using PCR (Table 1). Total colonoscopy showed multiple, white-coated, ulcerative lesions from the cecum to the sigmoid colon ( Fig 1B). The patient was treated with paromomycin monotherapy because her symptoms were mild, and she wished to avoid the PLOS NEGLECTED TROPICAL DISEASES PLOS Neglected Tropical Diseases | https://doi.org/10.

Diversity and Plasticity of Virulent Characteristics of Entamoeba histolytica

“…In the stage of E. histolytica , the trophozoites have the potential to survive and damage human tissues, and the cyst has been recognized as a non-pathogenic infectious form that spreads to other hosts [ 6 ]. In clinical settings, the cyst form has often been detected in stools of asymptomatic or colonization individuals, and can be a diagnostic trigger for these individuals [ 4 , 49 , 50 ]. Thus, there are some reports that mostly recognized those cyst carriers as identical to ‘asymptomatic or colonization’ infection by E. histolytica [ 21 , 37 , 51 ].…”

“…Taken together, these results suggest that the best therapy for asymptomatic individuals who present the mucus lesions detected via endoscopy remains undetermined. Paromomycin monotherapy may be a good selection [ 49 ], though it is unclear that the drug will adequate for all asymptomatic individuals. Further investigations are required to determine appropriate therapy for asymptomatic E. histolytica infection.…”

Drug Repurposing of the Alcohol Abuse Medication Disulfiram as an Anti-Parasitic Agent

“…No alternative therapies exist for those who experience toxicity from metronidazole, such as neurologic and dermatologic effects (Woodruff et al, 2002;Kumar et al, 2013;Mazumdar and Shome, 2014;Sørensen et al, 2018;Cappellari et al, 2020). This is illustrated in a recent report from Japan of two patients with ulcerative amebic colitis who received substandard therapy due to not being able to take metronidazole because of side effects (Yamamoto et al, 2020). Additionally, there are no treatment options if metronidazole resistance develops (Shirley et al, 2018;Kumanan et al, 2020).…”

COVID-19 and Corticosteroids: Unfamiliar but Potentially Fatal Infections That Can Arise following Short-Course Steroid Treatment

“…18,21,38,39 A combination of serology, stool antigen, and/or molecular tests often help establish diagnosis, although serology is more difficult to interpret in endemic settings because it may indicate either past or active infection, and antigen tests may be of low sensitivity, particularly for cyst-containing stool and asymptomatic infection. 38,40,41 Stool PCR is highly sensitive but use is limited in resource-poor settings. 21,42 Those with symptoms should be treated with an amebicidal agent, such as metronidazole, followed by a luminal agent, such as paromomycin.…”