The gut flora and environment are significantly altered in patients with severe SIRS. Abnormal gut flora and environment may affect systemic inflammatory response after severe insult.
A novel, strictly anaerobic, non-motile, non-spore-forming, Gram-negative, short, straight rod with tapered ends, designated YIT 12065T, was isolated from human faeces. Strain YIT 12065T was saccharolytic and negative for catalase, oxidase and urease, hydrolysis of aesculin and gelatin, nitrate reduction and indole production. The end products of glucose fermentation were acetic acid and a small amount of butyric acid. The DNA G+C content was 51.3 mol%. The predominant fatty acids were iso-C15 : 0, C16 : 0 and C14 : 0. Respiratory quinones were not detected. The cell wall contained glutamic acid, serine, alanine and ll-diaminopimelic acid. The whole-cell sugars were ribose, rhamnose, galactose and glucose. Phylogenetic analyses based on 16S rRNA gene sequences using three treeing algorithms revealed that the strain formed a novel family-level lineage within the phylum Firmicutes, class Clostridia, order Clostridiales. Caldicoprobacter oshimai JW/HY-331T was shown to be the closest named relative on the basis of 16S rRNA gene sequence similarity (86.9 %), followed by Tindallia californiensis DSM 14871T (86.3 %) and Clostridium ganghwense JCM 13193T (86.1 %). Similar 16S rRNA gene sequences (98.6–96.7 %) were found amongst faecal uncultured clones of human and dugong (Dugong dugon). They clustered with strain YIT 12065T in a distinct and deep evolutionary lineage of descent in the order Clostridiales. The distinct phylogenetic position supports the proposal of Christensenella gen. nov., with the type species Christensenella minuta sp. nov. (type strain YIT 12065T = DSM 22607T = JCM 16072T). A new family Christensenellaceae fam. nov. is also proposed.
BackgroundGut under severe insult is considered to have an important role in promoting infection and multiple organ dysfunction syndrome from the viewpoint of altered intestinal epithelium, immune system and commensal bacteria. There are few reports, however, about the relationship between gut flora and septic complications.MethodsWe analyzed gut flora in patients with systemic inflammatory response syndrome (SIRS) and evaluated key bacteria and their cutoff values for infectious complications and mortality by using classification and regression trees (CART). Eighty-one SIRS patients with a serum C-reactive protein level higher than 10 mg/dL treated in the intensive care unit (ICU) for more than 2 days were included for the study. We quantitatively evaluated nine types of bacteria in fecal samples by plate or tube technique. Two hundred seventy-one samples were analyzed using CART and logistic regression.ResultsThe dominant factors for complication of enteritis were the minimum number of total obligate anaerobes and the maximum number of Staphylococcus and Enterococcus. The dominant factors for complication of bacteremia were the minimum numbers of total obligate anaerobes and total facultative anaerobes. The dominant factors for mortality were the numbers of total obligate anaerobes and total facultative anaerobes and age.ConclusionsA decrease in total obligate anaerobes and an increase in pathogenic bacteria in the gut are associated with septic complications and mortality in patients with SIRS. The altered gut flora may be a potential prognostic marker in SIRS patients.
Isolation, cultivation, and characterization of the intestinal microorganisms are important for understanding the comprehensive physiology of the human gastrointestinal (GI) tract microbiota. Here, we isolated two novel bacterial strains, YIT 12067 T and YIT 12068, from the feces of healthy human adults. Phylogenetic analysis indicated that they belonged to the same species and were most closely related to Phascolarctobacterium faecium ACM 3679 T , with 91.4% to 91.5% 16S rRNA gene sequence similarities, respectively. Substrate availability tests revealed that the isolates used only succinate; they did not ferment any other short-chain fatty acids or carbohydrates tested. When these strains were cocultured with the xylan-utilizing and succinateproducing bacterium Paraprevotella xylaniphila YIT 11841 T , in medium supplemented with xylan but not succinate, their cell numbers became 2 to 3 orders of magnitude higher than those of the monoculture; succinate became undetectable, and propionate was formed. Database analysis revealed that over 200 uncultured bacterial clones from the feces of humans and other mammals showed high sequence identity (>98.7%) to YIT 12067 T . Real-time PCR analysis also revealed that YIT 12067 T -like bacteria were present in 21% of human fecal samples, at an average level of 3.34 ؋ 10 8 cells/g feces. These results indicate that YIT 12067 T -like bacteria are distributed broadly in the GI tract as subdominant members that may adapt to the intestinal environment by specializing to utilize the succinate generated by other bacterial species. The phylogenetic and physiological properties of YIT 12067 T and YIT 12068 suggest that these strains represent a novel species, which we have designated Phascolarctobacterium succinatutens sp. nov.A dvances in culture-independent molecular techniques have allowed a more complete and accurate assessment of the biodiversity of the ecosystem of the human gastrointestinal (GI) tract microbiota (10, 52) and have revealed that most of the phylotypes detected are uncultured (42). For a better understanding of the physiology of the human GI tract microbiota, it is important to isolate, cultivate, and characterize the intestinal microorganisms. Such undertakings provide information on the ecology and physiology of the GI tract microbiota that cannot be acquired from gene sequence information alone. For example, a study that used an isolated strain in the gnotobiotic mouse model revealed that one of the bacteria most frequently detected from human feces, Bacteroides thetaiotaomicron, modulates the expression of host genes involved in nutrient absorption, mucosal barrier fortification, xenobiotic metabolism, angiogenesis, and postnatal intestinal maturation (19). Therefore, cultivation of previously uncultured bacteria will also contribute to a more comprehensive understanding of the human GI tract microbiota through not only the phenotypic characterization of these species but also the sequencing of their whole genomes as a reference for metagenomic studies (53)...
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