In Vitro Responses of Plasmodium falciparum Isolates to Five Antimalaria Drugs in French Guiana during 1994 and 1995

Reynes, Jean-Marc; Fargette, Josiane; Gaborit, Pascal; Yarde, Steve

doi:10.1590/s0074-02761997000200019

Cited by 9 publications

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“…The percentage of the isolates that were resistant for each of the anti-malarial drugs tested per site based on published threshold IC 50 values discriminative for resistance is also shown in Additional file 1: Table S1. The literature IC 50 cut-off value indicative of resistance used in this study were chloroquine, 100 nM [19-21]; mefloquine, 30 nM [19,21,22]; amodiaquine, 80 nM [20-22]; lumefantrine, 150 nM [21,23]; doxycycline, 35 μM [21]; artesunate, 20 nM [21]; quinine, 800 nM [20,22]; dihydroartemisinin, 12 nM [21] and artemether, 30 nM [21,24]. Cut-off resistant values for piperaquine and tafenoquine were not available in the literature.…”

Section: Resultsmentioning

confidence: 99%

A SYBR Green 1-based in vitro test of susceptibility of Ghanaian Plasmodium falciparum clinical isolates to a panel of anti-malarial drugs

Quashie

Duah

Abuaku

et al. 2013

Malar J

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BackgroundBased on report of declining efficacy of chloroquine, Ghana shifted to the use of artemisinin-based combination therapy (ACT) in 2005 as the first-line anti-malarial drug. Since then, there has not been any major evaluation of the efficacy of anti-malarial drugs in Ghana in vitro. The sensitivity of Ghanaian Plasmodium falciparum isolates to anti-malarial drugs was, therefore, assessed and the data compared with that obtained prior to the change in the malaria treatment policy.MethodsA SYBR Green 1 fluorescent-based in vitro drug sensitivity assay was used to assess the susceptibility of clinical isolates of P. falciparum to a panel of 12 anti-malarial drugs in three distinct eco-epidemiological zones in Ghana. The isolates were obtained from children visiting health facilities in sentinel sites located in Hohoe, Navrongo and Cape Coast municipalities. The concentration of anti-malarial drug inhibiting parasite growth by 50% (IC50) for each drug was estimated using the online program, ICEstimator.ResultsPooled results from all the sentinel sites indicated geometric mean IC50 values of 1.60, 3.80, 4.00, 4.56, 5.20, 6.11, 10.12, 28.32, 31.56, 93.60, 107.20, and 8952.50 nM for atovaquone, artesunate, dihydroartemisin, artemether, lumefantrine, amodiaquine, mefloquine, piperaquine, chloroquine, tafenoquine, quinine, and doxycycline, respectively. With reference to the literature threshold value indicative of resistance, the parasites showed resistance to all the test drugs except the artemisinin derivatives, atovaquone and to a lesser extent, lumefantrine. There was nearly a two-fold decrease in the IC50 value determined for chloroquine in this study compared to that determined in 2004 (57.56 nM). This observation is important, since it suggests a significant improvement in the efficacy of chloroquine, probably as a direct consequence of reduced drug pressure after cessation of its use. Compared to that measured prior to the change in treatment policy, significant elevation of artesunate IC50 value was observed. The results also suggest the existence of possible cross-resistance among some of the test drugs.ConclusionGhanaian P. falciparum isolates, to some extent, have become susceptible to chloroquine in vitro, however the increasing trend in artesunate IC50 value observed should be of concern. Continuous monitoring of ACT in Ghana is recommended.

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Section: Resultsmentioning

confidence: 99%

A SYBR Green 1-based in vitro test of susceptibility of Ghanaian Plasmodium falciparum clinical isolates to a panel of anti-malarial drugs

Quashie

Duah

Abuaku

et al. 2013

Malar J

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“…The 50% inhibitory concentration (IC 50 ) was calculated using a probit/logit regression of the percentage of growth inhibition for each drug, and the geometric mean IC 50 s were compared by Student's t test. To comply with previous reports from the area and with the commonly used interpretation of susceptibility tests (5,14,15,20,26,28,29), we have used a cutoff value to classify isolates as susceptible, intermediate, or resistant ( Table 2). The in vitro levels of chloroquine resistance versus sensitivity were determined at the laboratory level by analyzing isolates from clinical cases with documented therapeutic efficacy from the area.…”

Section: Methodsmentioning

confidence: 99%

In Vitro Monitoring of Plasmodium falciparum Drug Resistance in French Guiana: a Synopsis of Continuous Assessment from 1994 to 2005

Legrand

Volney

Meynard

et al. 2008

Antimicrob Agents Chemother

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Implemented as one arm of the malaria control program in French Guiana in the early 1990s, our laboratory has since established in vitro profiles for parasite drug susceptibility to a panel of eight antimalarials for more than 1,000 Plasmodium falciparum isolates from infected patients. The quinine-doxycycline combination was introduced in 1995 as the first-line drug treatment against uncomplicated P. falciparum malaria, replacing chloroquine, and the first-line drug combination was changed to the artemether-lumefantrine combination in 2002. Resistance to chloroquine declined 5 years after it was dropped in 1995 as the first-line drug, but unlike similar situations in Africa, there was a rapid halt to this decline. Doxycycline susceptibility substantially decreased from 2002 to 2005, suggesting parasite selection under quinine-doxycycline drug pressure. Susceptibility to mefloquine decreased from 1997 onward. Throughout the period from 1994 to 2005, most isolates were sensitive in vitro to quinine, amodiaquine, and atovaquone. Susceptibility to amodiaquine was strongly correlated with that to chloroquine and to a lesser extent with that to mefloquine and halofantrine. Susceptibilities to mefloquine and to halofantrine were also strongly correlated. The Guyana Shield currently has the highest malaria rates in South America and is the only geographical area in the Americas where Plasmodium falciparum infection is diagnosed more frequently than P. vivax infection. In French Guiana, P. falciparum accounts for 60 to 70% of the 3,000 to 5,000 malaria cases reported every year (3). Malaria occurs in isolated geographical foci situated along the rivers in the Amazonian forest, and the population has little specific immunity. Malarial control involves spraying insecticides over the coastal region, where approximately 80% of the population resides, and using bed nets, an evidence-based drug policy, and deploying health services in remote endemic areas to provide prompt treatment by public primary health centers and/or private practitioners.As in the neighboring countries of the Amazon basin (36), P. falciparum is multidrug resistant, with failures documented for chloroquine (18), the amodiaquine/sulfadoxine-pyrimethamine combination (22), halofantrine (9, 19), chloroquine-proguanil (19), and even quinine (6). In the last decade, the drug policy in French Guiana has been based on both an in vivo assessment of therapeutic efficacy and longitudinal monitoring of in vitro drug susceptibility. In 1995, the quinine-doxycycline combination was recommended as the first-line treatment. It was replaced by the artemether-lumefantrine combination in 2002.Monitoring drug resistance is particularly important in this region, where illegal gold-mining activities in the malaria endemicity areas are associated with erratic consumption of antimalarials and frequently with self-medication, unclear compliance to recommended regimens, and the formulation and use of illegally imported molecules of unknown quality, which contribute to the select...

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“…Plasmodium falciparum malaria is a worrisome public health problem in its inland regions: it is estimated that between 3,000 and 5,000 proven cases occur each year, mostly along the Maroni River on the border with Suriname and the Oyapock River on the border with Brazil. 3,4 According to reliable in vitro drugsusceptibility surveillance data from the Pasteur Institute, 5 multi-drug resistance with reduced susceptibility to quinine has become common in this country in recent years. However, no reports are available concerning in vivo susceptibility to antimalarial drugs.…”

Section: Introductionmentioning

confidence: 99%

Plasmodium Falciparum in Vivo Resistance to Quinine: Description of Two Riii Responses in French Guiana

Demar¹,

Carme²

2004

The American Journal of Tropical Medicine and Hygiene

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The resistance of Plasmodium falciparum to antimalarial drugs is one of the most worrisome problems in tropical medicine, but few clinical studies or observations have described confirmed cases of therapeutic failure. We report two cases of in vivo P. falciparum resistance (RIII response) to quinine in French Guiana, an Amazonian focal zone in which multi-resistant malaria is endemic. Both patients presented with uncomplicated malaria and were initially treated with intravenous quinine. Although absorption was normal, the treatment was not effective and the patients still had fever and significant parasitemia three days after the onset of treatment (day 3). The addition of intravenous tetracycline completely resolved the parasitemia within approximately 96 hours. These clinical reports confirm the necessity to combine quinine with tetracycline in this area, as recommended by the recent French regional antimalarial policy.

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In Vitro Responses of Plasmodium falciparum Isolates to Five Antimalaria Drugs in French Guiana during 1994 and 1995

Cited by 9 publications

References 0 publications

A SYBR Green 1-based in vitro test of susceptibility of Ghanaian Plasmodium falciparum clinical isolates to a panel of anti-malarial drugs

A SYBR Green 1-based in vitro test of susceptibility of Ghanaian Plasmodium falciparum clinical isolates to a panel of anti-malarial drugs

In Vitro Monitoring of Plasmodium falciparum Drug Resistance in French Guiana: a Synopsis of Continuous Assessment from 1994 to 2005

Plasmodium Falciparum in Vivo Resistance to Quinine: Description of Two Riii Responses in French Guiana

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