BACKGROUND: Blastocystis is a human gut symbiont of yet undefined clinical significance. In a set of faecal samples collected from asymptomatic children of six distant populations, we first assessed the community profiles of protist 18S rDNA and then characterized Blastocystis subtypes and tested Blastocystis association with the faecal bacteriome community. METHODS: Stool samples were collected from 244 children and young persons (mean age 11.3 years, interquartile range 8.1-13.7) of six countries (Azerbaijan 51 subjects, Czechia 52, Jordan 40, Nigeria 27, Sudan 59 and Tanzania 15). The subjects showed no symptoms of infection. Amplicon profiling of the 18S rDNA was used for verification that Blastocystis was the most frequent protist, whereas specific real-time PCR showed its prevalence and quantity, and massive parallel amplicon sequencing defined the Blastocystis subtypes. The relation between Blastocystis and the stool bacteriome community was characterized using 16S rDNA profiling. RESULTS: Blastocystis was detected by specific PCR in 36% (88/244) stool samples and was the most often observed faecal protist. Children from Czechia and Jordan had significantly lower prevalence than children from the remaining countries. The most frequent subtype was ST3 (49%, 40/81 sequenced samples), followed by ST1 (36%) and ST2 (25%). Co-infection with two different subtypes was noted in 12% samples. The faecal bacteriome had higher richness in Blastocystis-positive samples, and Blastocystis was associated with significantly different community composition regardless of the country (p < 0.001 in constrained redundancy analysis). Several taxa differed with Blastocystis positivity or quantity: two genera of Ruminococcaceae were more abundant, while Bifidobacterium, Veillonella, Lactobacillus and several other genera were undrerrepresented. CONCLUSIONS: Asymptomatic children frequently carry Blastocystis, and co-infection with multiple distinct subtypes is not exceptional. Prevalence and quantity of the organism clearly differ among populations. Blastocystis is linked to both faecal bacteriome diversity and its composition.

• Keywords
• Africa, Asia, Bacteriome, Blastocystis, Type 1 diabetes,
• MeSH
• Asymptomatic Infections epidemiology   MeSH
• Blastocystis classification   genetics   isolation & purification   MeSH
• Blastocystis Infections epidemiology   parasitology   MeSH
• Child MeSH
• Feces parasitology   MeSH
• Genetic Variation MeSH
• Humans MeSH
• Adolescent MeSH
• Prevalence MeSH
• DNA, Protozoan genetics   MeSH
• DNA, Ribosomal genetics   MeSH
• Gastrointestinal Microbiome genetics   MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Azerbaijan epidemiology   MeSH
• Czechoslovakia epidemiology   MeSH
• Jordan epidemiology   MeSH
• Nigeria epidemiology   MeSH
• Sudan epidemiology   MeSH
• Tanzania epidemiology   MeSH
• Names of Substances
• DNA, Protozoan MeSH
• DNA, Ribosomal MeSH

The lung in cystic fibrosis (CF) is home to numerous pathogens that shorten the lives of patients. The aim of the present study was to assess changes in the lung bacteriome following antibiotic therapy targeting Pseudomonas aeruginosa in children with CF. The study included nine children (9-18 years) with CF who were treated for their chronic or intermittent positivity for Pseudomonas aeruginosa. The bacteriomes were determined in 16 pairs of sputa collected at the beginning and at the end of a course of intravenous antibiotic therapy via deep sequencing of the variable region 4 of the 16S rRNA gene, and the total bacterial load and selected specific pathogens were assessed using quantitative real-time PCR. The effect of antipseudomonal antibiotics was observable as a profound decrease in the total 16S rDNA load (p = 0.001) as well as in a broad range of individual taxa including Staphylococcus aureus (p = 0.03) and several members of the Streptococcus mitis group (S. oralis, S. mitis, and S. infantis) (p = 0.003). Improvements in forced expiratory volume (FEV1) were associated with an increase in Granulicatella sp. (p = 0.004), whereas a negative association was noted between the total bacterial load and white blood cell count (p = 0.007). In conclusion, the data show how microbial communities differ in reaction to antipseudomonal treatment, suggesting that certain rare species may be associated with clinical parameters. Our work also demonstrates the utility of absolute quantification of bacterial load in addition to the 16S rDNA profiling.

• MeSH
• Anti-Bacterial Agents administration & dosage   MeSH
• Bacteria classification   drug effects   genetics   isolation & purification   MeSH
• Cystic Fibrosis drug therapy   microbiology   MeSH
• Child MeSH
• DNA, Bacterial genetics   MeSH
• Humans MeSH
• Microbiota drug effects   MeSH
• Adolescent MeSH
• Lung microbiology   MeSH
• Pseudomonas Infections drug therapy   microbiology   MeSH
• Pseudomonas aeruginosa drug effects   genetics   isolation & purification   physiology   MeSH
• RNA, Ribosomal, 16S genetics   MeSH
• Sputum microbiology   MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• DNA, Bacterial MeSH
• RNA, Ribosomal, 16S MeSH