Trends in Parasitology
OpinionAssociations between Gut Microbiota and Common Luminal Intestinal Parasites
Section snippets
Towards Mapping of the Human Gut Eukaryome
An increasing body of evidence suggests links between gut microbiota composition and various diseases 1, 2, 3, 4, 5, 6. Application of a holistic view of the structure and function of the gut microbiota requires the inclusion of not only bacteria, but also parasites, fungi, archaea, viruses, and phages 7, 8, 9, 10, 11, 12. To some extent corroborating the ‘Old Friends hypothesis’ (see Glossary), Parfrey et al. recently produced data exemplifying the ‘defaunation’ of the human gut [13]. Here,
Evidence of Links between Common Intestinal Parasites and Gut Bacterial Communities
Over the past few years, specific gut microbiota patterns have been shown to be linked to colonization with common parasitic protists (Table 1). Especially, the relationship between Blastocystis and gut bacteria has been a popular research focus 15, 23, 34, 40, 41, 42, 43, 44, 45, 46. In 2011, Arumugam et al. launched the concept of enterotypes of the human gut microbiome [47]. Analysing the gut microbiota of healthy and diseased individuals across nations, they observed a clustering of
Associations between Microbial Signatures and Parasite Pathogenicity
A few examples of links between microbes and parasite pathogenicity have been published. One example is the study by Gilchrist and colleagues, who observed that a high parasite burden coupled with increased levels of Prevotella copri was linked to symptomatic infection with Entamoeba histolytica in Bangladeshi children [58]. Recently, members of the same group noticed that dysbiosis induced by antibiotic treatment increased the severity of amoebic colitis and delayed clearance of E. histolytica
How Can These Links Be Explored in Further Detail?
There are several ways in which to explore the above-mentioned links further. Some could involve studies of the parasite itself (including studies of the ecological requirements of the parasites – nutrition, oxygen tension, etc. – through genomic, transcriptomic, and metabolomic analyses). Others could involve exhaustive microbiota surveys and experimental studies. Conclusions based on cross-sectional data, which are the data mostly available at present, could be confirmed by using longitudinal
Perspectives
Probiotics have been used to prevent but also treat protozoal infections, exemplified in a recent review by Vitetta et al. [37], and so future investigations may benefit from looking deeper into how administration of probiotics might interfere with parasite colonization. In this context, it would also appear relevant to mention faecal microbiota transplantation (FMT), which has gained a lot in popularity over recent years, especially for the treatment of recurrent Clostridium difficile
Concluding Remarks
While we still know little about the potential pathogenicity of common luminal intestinal parasites, epidemiological data strongly suggest that at least some of these parasites are linked to gastrointestinal health rather than disease. Based on profiling of gut bacterial communities, we are learning to predict whether or not an individual is colonised with intestinal parasites. This article has provided some hypotheses and ideas for studies that could help us detail and strengthen our knowledge
Glossary
- 16S analysis
- also referred to by some as ‘metagenomic’ analysis. In fact, 16S analysis usually refers to the procedure in which genomic DNA from a given sample is subjected to broad-specificity amplification of bacterial small-subunit ribosomal DNA, sequenced by a next-generation sequencing method, and annotated to a taxonomic level by the use of online databases.
- Dysbiosis/Eubiosis
- the human gut is colonised primarily by species belonging to the following phyla: Firmicutes, Bacteroidetes,
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