National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA.
Universidad Nacional de Salta, Salta, Argentina.
Parasit Vectors. 2020 Apr 19;13(1):200. doi: 10.1186/s13071-020-04073-7.
Approximately 30% of children worldwide are infected with gastrointestinal parasites. Depending on the species, parasites can disrupt intestinal bacterial microbiota affecting essential vitamin biosynthesis.
Stool samples were collected from 37 asymptomatic children from a previous cross-sectional Argentinian study. A multi-parallel real-time quantitative PCR was implemented for Ascaris lumbricoides, Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Trichuris trichiura, Cryptosporidium spp., Entamoeba histolytica and Giardia duodenalis. In addition, whole-genome sequencing analysis was conducted for bacterial microbiota on all samples and analyzed using Livermore Metagenomic Analysis Toolkit and DIAMOND software. Separate analyses were carried out for uninfected, Giardia-only, Giardia + helminth co-infections, and helminth-only groups.
For Giardia-only infected children compared to uninfected children, DNA sequencing data showed a decrease in microbiota biodiversity that correlated with increasing Giardia burden and was statistically significant using Shannon's alpha diversity (Giardia-only > 1 fg/µl 2.346; non-infected group 3.253, P = 0.0317). An increase in diversity was observed for helminth-only infections with a decrease in diversity for Giardia + helminth co-infections (P = 0.00178). In Giardia-only infections, microbiome taxonomy changed from Firmicutes towards increasing proportions of Prevotella, with the degree of change related to the intensity of infection compared to uninfected (P = 0.0317). The abundance of Prevotella bacteria was decreased in the helminths-only group but increased for Giardia + helminth co-infections (P = 0.0262). Metagenomic analysis determined cobalamin synthesis was decreased in the Giardia > 1 fg/µl group compared to both the Giardia < 1 fg/µl and the uninfected group (P = 0.0369). Giardia + helminth group also had a decrease in cobalamin CbiM genes from helminth-only infections (P = 0.000754).
The study results may provide evidence for an effect of parasitic infections enabling the permissive growth of anaerobic bacteria such as Prevotella, suggesting an altered capacity of vitamin B12 (cobalamin) biosynthesis and potential impact on growth and development in children .
全世界约有 30%的儿童感染胃肠道寄生虫。根据物种的不同，寄生虫可能会破坏肠道细菌微生物群，从而影响必需维生素的生物合成。
从之前的阿根廷横断面研究中的 37 名无症状儿童中采集粪便样本。采用多平行实时定量 PCR 检测蛔虫、十二指肠钩虫、美洲板口线虫、粪类圆线虫、鞭虫、隐孢子虫、溶组织内阿米巴和蓝氏贾第鞭毛虫。此外，对所有样本的细菌微生物群进行全基因组测序分析，并使用 Livermore 宏基因组分析工具包和 DIAMOND 软件进行分析。分别对未感染、单纯贾第虫感染、贾第虫+蠕虫混合感染和单纯蠕虫感染组进行分析。
与未感染儿童相比，仅感染贾第虫的儿童的 DNA 测序数据显示微生物群多样性降低，这与贾第虫负担的增加相关，且使用 Shannon 多样性 alpha 分析具有统计学意义（仅感染贾第虫 >1 fg/µl 2.346；未感染组 3.253，P=0.0317）。仅感染蠕虫的感染中多样性增加，而贾第虫+蠕虫混合感染的多样性减少（P=0.00178）。在仅感染贾第虫的情况下，微生物组分类群从厚壁菌门向普雷沃氏菌属的比例增加，变化程度与未感染相比与感染强度相关（P=0.0317）。在仅感染蠕虫的组中，普雷沃氏菌属的丰度降低，但在贾第虫+蠕虫混合感染组中增加（P=0.0262）。宏基因组分析表明，与贾第虫 <1 fg/µl 组和未感染组相比，贾第虫 >1 fg/µl 组的钴胺素合成减少（P=0.0369）。贾第虫+蠕虫组的蠕虫感染也减少了钴胺素 CbiM 基因（P=0.000754）。
研究结果可能为寄生虫感染影响厌氧细菌（如普雷沃氏菌属）的允许生长提供了证据，表明维生素 B12（钴胺素）生物合成能力发生改变，并可能对儿童的生长发育产生影响。
