Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017536 (giardiasis)
 1,714 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 5-nitroimidazole (NI) compound C17, with a side chain carrying a remote phenyl group in the 2-position of the imidazole ring, is at least 14-fold more active against the gut protozoan parasite Giardialamblia than the 5-NI drug metronidazole (MTR), with a side chain in the 1-position of the imidazole ring, which is the primary drug for the treatment of giardiasis. Over 10 months, lines resistant to C17 were induced in vitro and were at least 12-fold more resistant to C17 than the parent strains. However, these lines had ID(90) values (concentration of drug at which 10% of control parasite ATP levels are detected) for MTR of >200 microM, whilst lines induced to be highly resistant to MTR in vitro have maximum ID(90) values around 100 microM (MTR-susceptible isolates typically have an ID(90) of 5-12.8 microM). The mechanism of MTR activation in Giardia apparently involves reduction to toxic radicals by the activity of pyruvate:ferredoxin oxidoreductase (PFOR) and the electron acceptor ferredoxin. MTR-resistant Giardia have decreased PFOR activity, which is consistent with decreased activation of MTR in these lines, but C17-resistant lines have normal levels of PFOR. Therefore, an alternative mechanism of resistance in Giardia must account for these super-MTR-resistant cells.
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PMID:A new-generation 5-nitroimidazole can induce highly metronidazole-resistant Giardia lamblia in vitro. 2045 26

Five-nitroimidazole (5-NI) compounds are among the most commonly used medications in the treatment of giardiasis. However, after more than five decades of their initial indication for such treatment, there are some concerns about the efficacy of 5-NIs in giardiasis. This study sought to compare the efficacy of any 5-NI with any other antigiardial drug for the treatment of Cuban children with giardiasis. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs). We searched CUMED, EBSCOhost and PubMed databases. Two reviewers independently assessed trial eligibility, trial quality and extracted appropriate data. The primary outcome was the parasitological cure. The effect estimate was the pooled relative risk (RR) with 95% confidence intervals (CI). We included seven RCTs in the systematic review, involving a total of 1046 children. When the effect of 5-NIs was compared with that of benzimidazole compounds, the pooled effect was significant and favored 5-NIs [the relative risk (RR) is 1.35, 95% CI =1.05 to 1.75], with high heterogeneity (4 studies, I2 =79%). Compared with chloroquine, the pooled effects of the 5-NIs were not significant [RR is 0.96, 95% CI=0.79 to 1.18, (2 studies, I2=68%)]. Our results support the use of 5-NIs (mainly tinidazole) as first-line therapy for Cuban pediatric patients infected with Giardia and may continue being used as reference drugs in future RCTs of giardiasis. These data could help inform policy decisions in Cuba. Caution is needed in extrapolating such data in other settings.
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PMID:Efficacy of 5-nitroimidazole compounds for giardiasis in Cuban children: systematic review and meta-analysis. 3088 80