title: Altered uptake of metronidazole in vitro by stocks of Giardia intestinalis with different drug sensitivities.
abstract: Growth of Giardia intestinalis in TYI-S-33 medium containing a sub-lethal concentration of metronidazole over a period of 66 weeks selected a line of organisms that was over 8 times less sensitive to the drug. This resistance was unstable and the organisms reverted to their original sensitivity within 22 weeks of growth in the absence of drug. A comparison of the uptake of [14C]metronidazole by the original and selected lines showed a highly significant reduction in drug uptake by the resistant line, indicating either a defective transport mechanism across the cell membrane or decreased reduction of metronidazole to the active metabolite within the cell. There was no significant difference in the uptake of metronidazole by 9 recent isolates of G. intestinalis maintained in axenic culture.
authors.affiliation: Queensland Institute of Medical Research, Herston, Brisbane, Australia.
authors.forename: P F
authors.initials: PF
authors.lastname: Boreham
authors.forename: R E
authors.initials: RE
authors.lastname: Phillips
authors.forename: R W
authors.initials: RW
authors.lastname: Shepherd
mesh_terms: D000818:Animals; D004351:Drug Resistance; D005872:Giardia / Q000378:metabolism*; D008795:Metronidazole / Q000378:metabolism*; D013997:Time Factors
chemical_list: D008795:Metronidazole