Quinacrine Treatment of Nitroimidazole-Refractory Giardiasis.

Background: Limited evidence exists on efficacy and tolerability of quinacrine for nitroimidazole-refractory giardiasis.

Methods: Nitroimidazole-refractory giardiasis cases, defined as microbiologically (microscopy and/or PCR) confirmed treatment failure after 2 courses, during 2008-2020, were retrospectively identified.

Results: Of 87 patients, 54 (62%) had visited India. Quinacrine was used in 54 (62%); 51 received monotherapy and 3 combined with metronidazole. Only 3 had positive stool samples with persisting symptoms after quinacrine treatment (94% parasitological efficacy) and all were cured after a second treatment. One (1.9%) had mild adverse effects recorded.

Conclusions: Quinacrine is an effective treatment for nitroimidazole-refractory giardiasis with good tolerability.