An Unusual Case of Extra-Enteric Blastocystosis in the Uterine Cervix.

Extra-enteric infections by Blastocystis spp. have rarely been documented. Here, we report a case of extra-enteric blastocystosis in a patient with minimal cervicitis symptoms. A 47-year-old Hispanic female patient was attended in a primary health centre in Michoacan state, Mexico, for her routine gynaecological medical examination. As only symptom, she referred to a slight vaginal itching. The presence of several vacuolar-stages of Blastocystis spp. were identified by Papanicolaou staining; molecular identification was attempted by culture-PCR sequencing of a region of 18S gene from cervical and faecal samples obtained 2 months after cytological examination, even when patient declared that she tried self-medicating with vaginal ovules. Blastocystis ST1 was identified only in the faecal sample. The presence of Blastocystis spp. in the cervix of a patient with scarce symptomatology, demonstrates the extraordinary flexibility of this microorganism to adapt to new environments and niches.

Comparison of the genetic variability of Blastocystis subtypes between human carriers from two contrasting climatic regions of México.

Blastocystis sp. is an anaerobic intestinal microorganism commonly identified in the feces of several animals, including humans. Blastocystis exhibits high genetic polymorphism and at least 17 subtypes (ST) have been identified; ST1-ST3 are frequently found in the Americas. Furthermore, in vitro assays have shown that temperature and humidity can affect the viability of Blastocystis cysts. In this study, we describe the genetic variability and genetic differentiation among and within Blastocystis STs in adults and children from the cities of Hermosillo and Morelia cities, which represent arid and humid subtropical climatic regions of México, respectively. Phylogenetic and genetic diversity was assessed by analyzing a region of the small subunit ribosomal DNA (SSU rDNA) gene as a marker. Blastocystis ST3 and ST1 were associated with children from Hermosillo and Morelia, respectively. An analysis of the nucleotide diversity (π) and haplotype polymorphism (θ) indexes showed that they were similar within each ST, but different between ST1 and ST3. Interestingly, the group of symptomatic carriers from Hermosillo showed scarce mean nucleotide diversity compared to the asymptomatic carriers (0.0039±0.0030 and 0.0329±0.0286, respectively). Furthermore, the gene flow and genetic differentiation indexes between the children and adults suggested that the Blastocystis haplotypes in the adult carriers were "highly mobile" among humans, while the haplotypes found in the children were more isolated and genetically differentiated between them.

Suitability of internal transcribed spacers (ITS) as markers for the population genetic structure of Blastocystis spp.

BACKGROUND: The purpose of this study was to assess the genetic variation and differentiation of Blastocystis subtypes (STs) recovered from symptomatic children by analysing partial sequences of the small subunit rDNA gene region (SSUrDNA) and internal transcribed spacers (1 and 2) plus the 5.8S region (ITS, ITS1 + 5.8S + ITS2) and comparing with isolates from other countries. FINDINGS: Faecal samples from 47 Blastocystis-infected children with gastrointestinal symptoms and negative for pathogenic enterobacteria were analysed. PCR was performed on DNA from all the samples to identify Blastocystis STs, amplifying a fragment of SSUrDNA and the ITS region. The amplicons were purified and sequenced, and consensus sequences were submitted to GenBank; afterwards, SSUrDNA sequences were analysed for genetic diversity according to geographic area. Regarding the Blastocystis STs found, 51% were ST1, 23% ST2, 19% ST3 and 2% ST7. For ITS, a haplotype network tree and Bayesian inference revealed the presence of two novel variants of ST1, clustering some sequences into ST1A and ST1B. The values of nucleotide diversity (π) and haplotype polymorphism (θ) for ST1, ST2 and ST3 ranged from 0 to 1, whereas the ratio of genetic differentiation (FST)/migration index (Nm) showed the highest differentiation between Libya and Thailand-Philippines for ST2 (0.282/0.63). In contrast, a high flow gene was observed between Czech Republic-Denmark-Holland-Spain and USA-Mexico-Colombia for ST1 (0.003/84). CONCLUSION: Our data on genetic differentiation and gene flow might explain the differences for the prevalence of Blastocystis STs. Moreover, the ITS region could be used as a genetic marker to assess genetic variation in this parasite.