BACKGROUND Sulfadoxine-pyrimethamine (SP) is a cornerstone of malaria chemoprophylaxis and is considered for programmes in the Democratic Republic of Congo (DRC). However, SP efficacy is threatened by drug resistance, that is conferred by mutations in the dhfr and dhps genes. The World Health Organization has specified that intermittent preventive treatment for infants (IPTi) with SP should be implemented only if the prevalence of the dhps K540E mutation is under 50%. There are limited current data on the prevalence of resistance-conferring mutations available from Eastern DRC. The current study aimed to address this knowledge gap. METHODS Dried blood-spot samples were collected from clinically suspected malaria patients [outpatient department (OPD)] and pregnant women attending antenatal care (ANC) in four sites in North and South Kivu, DRC. Quantitative PCR (qPCR) was performed on samples from individuals with positive and with negative rapid diagnostic test (RDT) results. Dhps K450E and A581G and dhfr I164L were assessed by nested PCR followed by allele-specific primer extension and detection by multiplex bead-based assays. RESULTS Across populations, Plasmodium falciparum parasite prevalence was 47.9% (1160/2421) by RDT and 71.7 (1763/2421) by qPCR. Median parasite density measured by qPCR in RDT-negative qPCR-positive samples was very low with a median of 2.3 parasites/µL (IQR 0.5-25.2). Resistance genotyping was successfully performed in RDT-positive samples and RDT-negative/qPCR-positive samples with success rates of 86.2% (937/1086) and 55.5% (361/651), respectively. The presence of dhps K540E was high across sites (50.3-87.9%), with strong evidence for differences between sites (p < 0.001). Dhps A581G mutants were less prevalent (12.7-47.2%). The dhfr I164L mutation was found in one sample. CONCLUSIONS The prevalence of the SP resistance marker dhps K540E exceeds 50% in all four study sites in North and South Kivu, DRC. K540E mutations regularly co-occurred with mutations in dhps A581G but not with the dhfr I164L mutation. The current results do not support implementation of IPTi with SP in the study area.

中文翻译：

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刚果民主共和国东部对磺胺多辛-乙胺嘧啶的抗药性标记；疟疾化学预防的意义。

背景技术磺胺多辛-乙胺嘧啶（SP）是疟疾化学预防的基石，并被考虑用于刚果民主共和国（DRC）的计划。但是，SP效力受到耐药性的威胁，这是由dhfr和dhps基因的突变赋予的。世界卫生组织规定，只有在dhps K540E突变的患病率低于50％的情况下，才应对SP的婴儿进行间歇性预防治疗（IPTi）。从东部DRC获得的有关赋予抗性的突变发生率的最新数据有限。当前的研究旨在解决这一知识鸿沟。方法从北卡州和南基伍省的四个地点，从临床可疑的疟疾患者[门诊（OPD）]和参加产前护理（ANC）的孕妇中采集干血斑样品。快速诊断测试（RDT）结果为阳性和阴性的个体样品均进行了定量PCR（qPCR）。通过巢式PCR评估Dhps K450E和A581G和dhfr I164L，然后进行等位基因特异性引物延伸，并通过基于多重磁珠的测定进行检测。结果在整个人群中，恶性疟原虫的寄生虫患病率通过RDT检测为47.9％（1160/2421），通过qPCR检测为71.7（1763/2421）。在RDT阴性的qPCR阳性样品中，通过qPCR测量的中位寄生虫密度非常低，中位值为2.3寄生虫/ µL（IQR 0.5-25.2）。在RDT阳性样品和RDT阴性/ qPCR阳性样品中成功进行了抗性基因分型，成功率分别为86.2％（937/1086）和55.5％（361/651）。跨站点的dhps K540E的存在率很高（50.3-87.9％），有力的证据证明站点之间存在差异（p <0.001）。Dhps A581G突变体的流行率较低（12.7-47.2％）。在一个样本中发现dhfr I164L突变。结论在北卡罗来纳州和南基伍的所有四个研究地点，SP抗性标记dhps K540E的患病率均超过50％。K540E突变通常与dhps A581G中的突变共同发生，但与dhfr I164L突变不同时发生。当前的结果不支持在研究区域中使用SP实施IPTi。