Phenotypic and genotypic variation in Giardia lamblia isolates during chronic infection

Two Giardia isolates were axenised in vitro after recovery by duodenal aspiration from a man with hypo-gamma globulinaemia and chronic giardiasis, before and after three unsuccessful courses of metronidazole. In vitro drug sensitivity assays showed that the pretreatment isolate was sensitive to metr...

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Bibliographic Details
Published in:Gut 1994-01, Vol.35 (1), p.51-54
Main Authors: Butcher, P D, Cevallos, A M, Carnaby, S, Alstead, E M, Swarbrick, E T, Farthing, M J
Format: Article
Language:English
Subjects:
Adult
Animals
Antibiotics. Antiinfectious agents. Antiparasitic agents
Antiparasitic agents
Biological and medical sciences
Chronic Disease
DNA Fingerprinting
Genotype
Giardia lamblia - classification
Giardia lamblia - drug effects
Giardia lamblia - genetics
Giardiasis - drug therapy
Giardiasis - parasitology
Humans
Isoenzymes - analysis
Male
Medical sciences
Metronidazole - pharmacology
Pharmacology. Drug treatments
Phenotype
Protozoan Proteins - analysis
Quinacrine - pharmacology
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Summary:Two Giardia isolates were axenised in vitro after recovery by duodenal aspiration from a man with hypo-gamma globulinaemia and chronic giardiasis, before and after three unsuccessful courses of metronidazole. In vitro drug sensitivity assays showed that the pretreatment isolate was sensitive to metronidazole with minimum inhibitory concentration (MIC) and dose that inhibited growth by 50% (ED50) values of 0.1 and 0.03 mumol/l, respectively. The post-treatment isolate was 20-fold more resistant (MIC and ED50 4.3 and 0.58 mumol/l, respectively). Differences between these isolates were also found in the surface protein profiles after radioiodination, metabolic labelling patterns with 35S-methionine, malic enzyme isoenzyme patterns, and by DNA fingerprinting with a M-13 bacteriophage probe. The phenotypic and genotypic differences between the pretreatment and post-treatment isolates suggest that we have isolated two different strains from the same patient and that treatment with metronidazole resulted in selection of the more resistant strain.
ISSN:0017-5749
1468-3288
1458-3288
DOI:10.1136/gut.35.1.51