坦桑尼亚东海岸普通人群中出现磺胺多辛-乙胺嘧啶耐药性的七重突变以及Pfdhfr-Pfdhps五重突变上升，这对孕期使用磺胺多辛-乙胺嘧啶预防疟疾构成了威胁。
Occurrence of septuple and elevated Pfdhfr-Pfdhps quintuple mutations in a general population threatens the use of sulfadoxine-pyrimethamine for malaria prevention during pregnancy in eastern-coast of Tanzania.
作者信息
Bwire George M, Mikomangwa Wigilya P, Kilonzi Manase
机构信息
Department of Pharmaceutical Microbiology, Muhimbili University of Health and Allied Sciences, P.O. Box 65013, Dar es Salaam, Tanzania.
Department of Clinical Pharmacy and Pharmacology, Muhimbili University of Health and Allied Sciences, P.O. Box 65013, Dar es Salaam, Tanzania.
出版信息
BMC Infect Dis. 2020 Jul 22;20(1):530. doi: 10.1186/s12879-020-05253-7.
BACKGROUND
Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthetase (Pfdhps) mutations compromise the effectiveness of sulfadoxine-pyrimethamine (SP) for treatment of uncomplicated malaria, and are likely to impair the efficiency of intermittent preventive treatment during pregnancy (IPTp). This study was conducted to determine the level of Pfdhfr-Pfdhps mutations, a decade since SP was limited for IPTp use in pregnant women in Tanzania.
METHODS
P. falciparum genomic DNA was extracted from dried blood spots prepared from a finger prick. Extracted DNA were sequenced using a single MiSeq lane by combining all PCR products. Genotyping of Pfdhfr and Pfdhps mutations were done using bcftools whereas custom scripts were used to filter and translate genotypes into SP resistance haplotypes.
RESULTS
The Pfdhfr was analyzed from 445 samples, the wild type (WT) Pfdhfr haplotype NCSI was detected in 6 (1.3%) samples. Triple PfdhfrIRNI (mutations are bolded and underlined) haplotype was dominant, contributing to 84% (number [n] = 374) of haplotypes while 446 samples were studied for Pfdhps, WT for Pfdhps (SAKAA) was found in 6.7% (n = 30) in samples. Double Pfdhps haplotype (SGEAA) accounted for 83% of all mutations at Pfdhps gene. Of 447 Pfdhfr-Pfdhps combined genotypes, only 0.9% (n = 4) samples contained WT gene (SAKAA-NCSI). Quintuple (five) mutations, SGEAA-IRNI accounted for 71.4% (n = 319) whereas 0.2% (n = 1) had septuple (seven) mutations (AGKGS-IRNI). The overall prevalence of Pfdhfr K540E was 90.4% (n = 396) while Pfdhps A581G was 1.1% (n = 5).
CONCLUSIONS
This study found high prevalence of Pfdhfr-Pfdhps quintuple and presence of septuple mutations. Mutations at Pfdhfr K540E and Pfdhps A581G, major predictors for IPTp-SP failure were within the recommended WHO range. Abandonment of IPTp-SP is recommended in settings where the Pfdhfr K540E prevalence is > 95% and Pfdhps A581G is > 10% as SP is likely to be not effective. Nonetheless, saturation in Pfdhfr and Pfdhps haplotypes is alarming, a search for alternative antimalarial drug for IPTp in the study area is recommended.
背景
恶性疟原虫二氢叶酸还原酶（Pfdhfr）和二氢蝶酸合酶（Pfdhps）突变会损害磺胺多辛-乙胺嘧啶（SP）治疗单纯性疟疾的效果，并且可能会削弱孕期间歇性预防治疗（IPTp）的效果。本研究旨在确定自坦桑尼亚限制孕妇使用SP进行IPTp已有十年之久的情况下，Pfdhfr - Pfdhps突变的水平。
方法
从手指针刺采集的干血斑中提取恶性疟原虫基因组DNA。将所有PCR产物合并后，使用单个MiSeq泳道对提取的DNA进行测序。使用bcftools对Pfdhfr和Pfdhps突变进行基因分型，而使用自定义脚本对基因型进行过滤并将其转化为SP耐药单倍型。
结果
对445个样本的Pfdhfr进行了分析，在6个（1.3%）样本中检测到野生型（WT）Pfdhfr单倍型NCSI。三重PfdhfrIRNI（突变加粗并加下划线）单倍型占主导地位，占单倍型的84%（数量[n]=374），同时对446个样本进行了Pfdhps研究，在样本中发现WT型Pfdhps（SAKAA）占6.7%（n = 30）。双重Pfdhps单倍型（SGEAA）占Pfdhps基因所有突变的83%。在447个Pfdhfr - Pfdhps联合基因型中，只有0.9%（n = 4）的样本包含WT基因（SAKAA - NCSI）。五重（五个）突变SGEAA - IRNI占71.4%（n = 319），而0.2%（n = 1）有七重（七个）突变（AGKGS - IRNI）。Pfdhfr K540E的总体患病率为90.4%（n = 396），而Pfdhps A581G为1.1%（n = 5）。
结论
本研究发现Pfdhfr - Pfdhps五重突变的高患病率以及七重突变的存在。Pfdhfr K540E和Pfdhps A581G的突变是IPTp - SP失败的主要预测指标，在世界卫生组织推荐范围内。在Pfdhfr K540E患病率>95%且Pfdhps A581G患病率>10%的地区，由于SP可能无效，建议放弃IPTp - SP。尽管如此，Pfdhfr和Pfdhps单倍型的饱和令人担忧，建议在研究地区寻找用于IPTp的替代抗疟药物。
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