Distinguishing feature of gut microbiota in Tibetan highland coronary artery disease patients and its link with diet.

The prevalence of coronary artery disease (CAD) in Tibetan Highlanders is lower than that in plain-living individuals, but the mechanism still unclear. Gut microbiota (GM) disorder is considered one of the potential factors involved in the pathogenesis of CAD, but the GM characteristics of Tibetan Highlanders suffering from CAD are unknown. We sequenced the V3-V4 region of the 16S ribosomal RNA of gut bacteria from fecal samples from Tibetan and Han CAD patients and healthy individuals inhabiting the Qinghai-Tibet Plateau, as well as from Han CAD patients and healthy individuals living at sea level, and we analyzed the GM characteristics of these subjects by bioinformatics analysis. The results showed that Tibetan Highlanders suffering from CAD had higher GM α-diversity, with differently distributed cluster compared with healthy Tibetan Highlanders and Han CAD patients living at high and low altitudes. Genera Catenibacterium, Clostridium_sensu_stricto, Holdemanella, and Ruminococcus 2 were enriched in Tibetan Highlanders suffering from CAD compared with healthy Tibetan Highlanders and Han CAD patients living at high- and low-altitudes. Prevotella was enriched in Tibetan Highlanders suffering from CAD compared with Han CAD patients living at high- and low-altitudes. Moreover, Catenibacterium was positively correlated with Prevotella. Additionally, Catenibacterium, Holdemanella, and Prevotella were positively correlated with fermented dairy product, carbohydrate and fiber intake by the subjects, while Clostridium_sensu_stricto was negatively correlated with protein intake by the subjects. In conclusion, our study indicated that Tibetan Highlanders suffering from CAD showed distinct GM, which was linked to their unique dietary characteristics and might associated with CAD.

Interaction of Intestinal Bacteria with Human Rotavirus during Infection in Children.

The gut microbiota has emerged as a key factor in the pathogenesis of intestinal viruses, including enteroviruses, noroviruses and rotaviruses (RVs), where stimulatory and inhibitory effects on infectivity have been reported. With the aim of determining whether members of the microbiota interact with RVs during infection, a combination of anti-RV antibody labeling, fluorescence-activated cell sorting and 16S rRNA amplicon sequencing was used to characterize the interaction between specific bacteria and RV in stool samples of children suffering from diarrhea produced by G1P[8] RV. The genera Ruminococcus and Oxalobacter were identified as RV binders in stools, displaying enrichments between 4.8- and 5.4-fold compared to samples nonlabeled with anti-RV antibodies. In vitro binding of the G1P[8] Wa human RV strain to two Ruminococcus gauvreauii human isolates was confirmed by fluorescence microscopy. Analysis in R. gauvreauii with antibodies directed to several histo-blood group antigens (HBGAs) indicated that these bacteria express HBGA-like substances on their surfaces, which can be the target for RV binding. Furthermore, in vitro infection of the Wa strain in differentiated Caco-2 cells was significantly reduced by incubation with R. gauvreauii. These data, together with previous findings showing a negative correlation between Ruminococcus levels and antibody titers to RV in healthy individuals, suggest a pivotal interaction between this bacterial group and human RV. These results reveal likely mechanisms of how specific bacterial taxa of the intestinal microbiota could negatively affect RV infection and open new possibilities for antiviral strategies.

Ruminococcus gnavus bacteremia, an uncommon presentation of a common member of the human gut microbiota: case report and literature review.

Case report: We present a case of a 66-year-old female diagnosed with R. gnavus bacteremia associated with fecal peritonits secondary to small-bowel herniation and perforation. Identification  as R. gnavus was delayed because of absence of this species in the MALDI-TOF MS database (Vitek MS, bioMérieux). Identification was provided by 16S rRNA gene sequencing. Review: R. gnavus, a Gram-positive, strictly anaerobic bacterium, is a member of the human gut microbiota. Dysbiosis in the gut microbiota, with increased amounts of R. gnavus, has been described in inflammatory bowel disease. R. gnavus has only been reported occasionally as the cause of infections. Hence the potential pathogenicity is not yet fully recognized, and data regarding the antimicrobial susceptibility profile are rare. Identification of anaerobic bacteria such as R. gnavus is greatly accelerated  as a result of the introduction of MALDI-TOF MS. However, as illustrated in this case report, an extensive and up-to-date MALDI-TOF MS database is necessary for providing an accurate identification.

[Liver abscess and infective endocarditis cases caused by Ruminococcus productus]. / Ruminococcus productus'un etken oldugu karaciger apsesi ve enfektif endokardit olgulari.

The genus Ruminococcus which are anaerobe Gram positive cocci, previously classified as Peptostreptococcus, may colonize the upper respiratory tract, gastrointestinal tract, vagina and skin of humans and animals. In this report a case of liver abscess and a case of infective endocarditis caused by Ruminoccocus productus, which is very rarely encountered in the clinical practice were presented. The first case was a 32 years old male who was admitted to the hospital in 2002, with the complaints of fever lasting for 20 days and pain while breathing. The abdominal ultrasonography revealed the presence of a liver abscess, and the drainage material from the abscess yielded Ruminococcus productus, identified in BACTEC 9200 (Becton Dickinson, Sparks, Md) anaerobe system. As the isolate was found to be sensitive to penicilin, the empirical gentamicin and ampicillin/sulbactam therapy was continued. The second case was a 25 years old male who was admitted to the hospital in 2005, with the signs of fever lasting for 3-4 months, chills, bone and joint pains. As multiple vegetations were detected in echocardiography, blood cultures were collected and empirical therapy with ceftriaxone and gentamicin was initiated with the preliminary diagnosis of infective endocarditis. Bacteria which were isolated from blood cultures by BACTEC 9200 system have been identified as R. productus. As this strain was also sensitive to penicillin, the empirical therapy was changed to penicilin and gentamicin. These two cases indicated that R. productus should be considered in complicated infections even if it is a rarely isolated species from the clinical samples.