[In vitro measurement of nitazoxanide sensitivity of 4 Giardia duodenalis isolates obtained from different hosts].
BACKGROUND
In Mexico giardiosis is the most prevalent parasitic disease in children. Treatment with antiparasitics derived from: nitroimidazoles, benzimidazoles and nitrofuranes have been used; but, some of them have undesirable side effects. Recently nitazoxanide (Ntz) was introduced in Mexico; however, there are few studies on Giardia duodenalis susceptibility to Ntz.


OBJECTIVE
To determine G. duodenalis sensitivity to Ntz and compare it to tinidazole (Tnz).


METHODS
Assays were performed in four G. duodenalis isolates: INP231087MM, INP210897-AXA1 obtained from humans infections, INP170693HG8, INP300693-CP5 from a cat and a dog, respectively. Half million trophozoites were exposed to different Ntz or Tnz concentrations in TYI-S-33, for 24 hours at 37 degrees C. Trophozoite viability was tested by the colorimetric method of MTT-tetrazolium salts reduction to MTT-formazan. To analyze ultrastructural damage, control and experimental samples were processed by standard electron microscopy methods. Experiments were carried out, in a double blind in triplicate and repeated four times. Results were analyzed by variance analysis.


RESULTS
Susceptibility at 100% were in a Ntz concentration ranging from 1 microgram to 7 micrograms and in a Tnz concentration ranging from 1 microgram to 4 micrograms. There were significant differences when sensitivities to Ntz were compared between them (P < 0.001). The ultrastructural analysis showed changes in trophozoite volume, loss of characteristic shape and swelling.


CONCLUSIONS
This is the first report of G. duodenalis susceptibility to Ntz performed in isolates from different hosts. G. duodenalis isolates were more susceptible to Tnz than Ntz.
Ponce-Macotela
M
M
Instituto Nacional de Pediatría, UNAM. macotelam@yahoo.com
Gómez-Garduño
J
J
González-Maciel
A
A
Reynoso-Robles
R
R
Anislado-Tolentino
V
V
Martínez-Gordillo
M N
MN
D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D002371:Cat Diseases / Q000469:parasitology; D002415:Cats; D002648:Child; D002675:Child, Preschool; D004283:Dog Diseases / Q000469:parasitology; D004285:Dogs; D004311:Double-Blind Method; D004351:Drug Resistance; D004386:Duodenum / Q000469:parasitology; D005872:Giardia / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D005873:Giardiasis / Q000469:parasitology* / Q000662:veterinary; D006801:Humans; D007411:Intestinal Diseases, Parasitic / Q000469:parasitology* / Q000662:veterinary; D008297:Male; D008826:Microbial Sensitivity Tests; D009574:Nitro Compounds; D013045:Species Specificity; D013844:Thiazoles / Q000494:pharmacology*; D014011:Tinidazole / Q000494:pharmacology
D000981:Antiprotozoal Agents; D009574:Nitro Compounds; D013844:Thiazoles; D014011:Tinidazole; C041747:nitazoxanide