Blastocystosis: principles and methods of treatment (Information letter)

Abstract

Blastocystosis is a common protozoan intestinal disease in humans, caused by unicellular, anaerobic eukaryotic parasites of the genus Blastocystis, which primarily colonize the large intestine, leading to functional and pathomorphological disorders in the digestive system and other organs and tissues. All patients with blastocystosis (both immunocompromised and immunocompetent) require complex treatment, an important component of which is etiotropic therapy. Since there are still no generally accepted guidelines for the etiotropic therapy of blastocystosis, the modern approach to the selection and dosing of antiprotozoal agents is based on data on the sensitivity of regional clinical strains of Blastocystis sp. to these agents, which is most often determined by in vitro tests. Based on the results of an in vitro study of the susceptibility of 15 Blastocystis sp. strains isolated in Ukraine from patients with blastocystosis to the action of predictive bioequivalent concentrations (PBCs) of a group of antiparasitic drugs, it was established that all parasite isolates were most sensitive to nitazoxanide (NTZ), paramomycin (PAR), metronidazole (MTZ), and moderately sensitive to co-trimoxazole (COT; trimethoprim/sulfamethoxazole). Taking into account the experimental data and actual circumstances, when NTZ and PAR are not yet registered in Ukraine, it is proposed to use MTZ as a first-line drug for the etiotropic therapy of patients with blastocystosis, and COT as an alternative second-line drug. To increase the effectiveness of blastocystosis treatment, it is recommended to follow these dosage rules for these medications. MTZ dosage: 500 mg, three times a day (every 8 hours), for a course of 7–10 days. COT dosage: 1920 mg (320 mg trimethoprim/1600 mg sulfamethoxazole), twice daily (every 12 hours), for a course of 7–10 days. The performance of blastocystosis treatment is assessed using clinical and parasitological efficacy criteria.