This Month in Blastocystis Research (MAY 2013)

Now, we have a situation. Last month, I came up with the idea of the post series 'This Month in Blastocystis Research' developed for discussing a couple of papers on Blastocystis appearing recently in pubmed. However, this month only one Blastocystis release has emerged. It is in Turkish with an English abstract and so I'm not in the optimum position to review it. Overall, I'm not entirely clear on why the authors have chosen to publish the work. The paper is apparently about PCR amplification of Blastocystis specific DNA (using the barcoding primers) with subsequent cloning with a view to producing subtype information that could have been obtained simply by direct sequencing. At least when the goal is to subtype a particular positive sample, PCR + sequencing should suffice. Obviously, if you want to explore intra-subtype diversity, cloning is very useful. But it is time consuming for subtyping and also expensive. Therefore, for plain subtyping, I recommend the protocol that I put out on youtube a few weeks ago. The phylogenetic tree produced by the authors looks unfamiliar to me in that the clustering of the subtypes is quite different from the phylogenies inferred by other groups; this should not have anything to do with the SSU rDNA region explored; rather it may boil down to issues with alignment editing or the algorithm chosen for phylogenetic analysis. Well, we should be looking forward to more subtype data from Turkey! Incidentally, I was once involved in a Turkish study where we found ST1, ST2 and ST3 mainly, while ST4 was rare.

Since there are no other papers to discuss, I will try and compensate by providing a link to 'This Week in Parasitism' hosted by Vincent Racaniello and Dickson Despommier, who are going through a case of Blastocystis possibly contracted abroad during a field trip to Bali. Now, there's a lot of digression in this pod cast (some of which is actually quite enjoyable). Also, I do not agree with all the things said about Blastocystis in this conversation. If you cannot make the link work, you can access the podcast directly here. 

I do think it's a bit strange though that given the clinical focus of the talk, there is not a single word on paromomycin. But I guess the overall take home message is that treating Blastocystis is really difficult, and no single type of therapeutic intervention is consistently efficacious. Unfortunately, the two gentlemen do not touch upon the genetic diversity of Blastocystis, which is probably one of the most interesting things about Blastocystis currently known, and which may also be part of the reason why no single treatment modality seems to work every single time.

I wonder whether Blastocystis will always be stuck in shades of grey... or whether at some point we'll be able to make some clear-cut conclusions that will be useful for clinicians and clinical microbiologists...? I hope! And I believe we are certainly on our way!

Anyway, enjoy a bit of Blastocystis causerie!

Suggested reading:

Sakalar C, Uyar Y, Yürürdurmaz MA, Tokar S, Yeşilkaya H, Gürbüz E, Kuk S, & Yazar S (2013). [Cloning of Blastocystis sp Subtype 3 Small-subunit Ribosomal DNA]. Turkiye Parazitolojii Dergisi / Turkiye Parazitoloji Dernegi = Acta Parasitologica Turcica / Turkish Society for Parasitology, 37 (1), 13-8 PMID: 23619039

Ozyurt M, Kurt O, Mølbak K, Nielsen HV, Haznedaroglu T, & Stensvold CR (2008). Molecular epidemiology of Blastocystis infections in Turkey. Parasitology International, 57 (3), 300-6 PMID: 18337161

Nature Editorial (2013). Shades of grey Nature, 497 (7450), 410-410 DOI: 10.1038/497410a