In vitro chloroquine resistance for Plasmodium vivax isolates from the Western Brazilian Amazon

Abstract

BackgroundChloroquine (CQ) and primaquine (PQ) are still the drugs of choice to treat Plasmodium vivax malaria in many endemic areas, Brazil included. There is in vivo evidence for the P. vivax resistance to CQ in the Brazilian Amazon, where the increase in the proportion of P. vivax malaria parallels the increase of unusual clinical complications related to this species. In this study, in vitro CQ and mefloquine (MQ)-susceptibility of P. vivax isolates from the Western Brazilian Amazon was tested using the double-site enzyme-linked lactate dehydrogenase immunodetection (DELI) assay.MethodsA total of 112 P. vivax isolates were tested in vitro for CQ-susceptibility and out of these 47 were also tested for MQ-susceptibility. The DELI assay was used to detect P. vivax growth at 48-hour short-term culture in isolates with ring stages ranging from 50 to %. Each isolate was tested in triplicate and geometric means of IC50’s was obtained. Nineteen isolates were genetically characterized for pvdhfr, pvmrp1, pvmdr1 and pvdhps candidate genes likely related to CQ resistance (10 with IC50<40 nM and 9 with IC50 >100 nM).ResultsTwelve out of 112 isolates were considered resistant to CQ, resulting in 10.7% (IC95% 5.0-16.4), while 3 out of 47 (6.4%; IC95% 0.0-12.8) were resistant to MQ. A discrete correlation was observed between IC50’s of CQ and MQ (Spearman=0.294; p=0.045). For pvdhps gene, a non-synonymous mutation was found at codon 382 (S→C) in 5/8 CQ-sensitive samples and 1/9 CQ-resistant samples (p=0.027). The other molecular markers were not associated to CQ-susceptibility.ConclusionsIn vitro CQ-resistance estimated in this study, estimated by the DELI test, was very similar to that observed in clinical trials, suggesting that in vitro procedures developed by capable local laboratories are useful in the surveillance of CQ-resistance in the Amazon; concurrent Amazon P. vivax strains with both CQ and MQ resistance may be common; and a non-synonymous mutation at pvdhps codon 382 (S→C) was associated to in vitro susceptibility to CQ, needing further studies to be confirmed.

In Vitro Susceptibility of Plasmodium vivax to Antimalarials in Colombia

“…However, ongoing clinical efficacy monitoring would be important, in addition to integrated in vitro susceptibility and molecular marker studies. For example, in the Amazonian region of Brazil, in 2013, Chehuan et al (42) reported that 12 (10.7%) out of 112 isolates with an IC 50 of Ͼ100 nM were considered resistant to CQ, while 3 (6.4%) of 47 were considered resistant to MQ. The same study showed that Amazonian P. vivax strains with both CQ and MQ resistance may be common, and a nonsynonymous mutation at pvdhps codon 382 (S¡C) was associated with in vitro susceptibility to CQ; thus, (Table 5).…”

Ethnopharmacological evaluation of medicinal plants used against malaria by quilombola communities from Oriximiná, Brazil

“…P. falciparum parasites are vastly resistant to chloroquine, as well to pyrimethamine and sulfadoxine (WHO, 2012). Cases of therapeutic failure of P. vivax malaria after cloroquine treatment have been reported in Brazil, and this parasite is already resistant in other parts of the world (Chehuan et al, 2013;Price et al, 2009;Suwanarusk et al, 2007) The principal antimalarial treatment, effective against human malaria appeared approximately 1770 and contained infusions of bark from the Cinchona sp trees, a plant native to the Peruvian Amazon. After many years of empirical phytotherapy, the alkaloid quinine was identified in this plant species by French chemists as being responsible for the plant activity (in Garnham, 1966).…”

Plasmodium vivax multidrug resistance-1 gene polymorphism in French Guiana

“…In French Guiana, it is currently responsible for two-thirds of malaria cases. Resistance to chloroquine, the main treatment used against vivax malaria [2], has been reported in the Brazilian Amazon Region [4, 17, 18, 20, 21, 32, 36, 37]. In French Guiana, the development of gold-mining activities and the consequent human migration between French Guiana and neighbouring countries, Brazil and Suriname [4, 38, 39], have raised fears that chloroquine-resistant P. vivax isolates may spread.…”

“…It was only in 1996 that the first confirmed clinical case of resistance was described in Brazil [8]. Chloroquine resistance has spread around the world over the last decade [9], and is now found in Southeast Asia [10–14] but also in Africa [15, 16], South America [8, 17–22] and the Middle East [23, 24]. …”