Anaerobe最新文献

Introduction

Bacteroides fragilis (B. fragilis) is considered to act in an anti-inflammatory manner on the intestinal tract. On the contrary, enterotoxigenic B. fragilis (ETBF), a subtype of B. fragilis, produces an enterotoxin (BFT; B. fragilis toxin), leading to asymptomatic chronic infections and colonic tumor formation. However, the impact of B. fragilis and ETBF on the clinical outcome of colorectal cancer (CRC) remains unclear. We aim to assess whether their presence affects the outcome in patients with CRC after curative resection.

Methods

We obtained 197 pairs of matched formalin-fixed paraffin-embedded samples from cancerous and adjacent non-cancerous tissues of patients with pathological stage (pstage) II and III CRC after curative resection. The presence of B. fragilis and ETBF were estimated using real-time polymerase chain reaction, and recurrence-free survival (RFS) and overall survival (OS) of the patients were analyzed.

Results

16 S rRNA for B. fragilis and bft DNA were detected in 120 (60.9%) and 12 (6.1%) of the 197 patients, respectively. B. fragilis-positive patients had better RFS than B. fragilis-negative patients, although that was not statistically significant. In subgroup analysis, better outcomes on RFS were observed in the presence of B. fragilis in pstage II and left-sided CRC. The association of B. fragilis positivity on OS was accentuated in the depth of T4 subgroup. No significant differences were observed in RFS and OS between ETBF and non-toxigenic B. fragilis.

Conclusions

Our findings suggest that the presence of B. fragilis is associated with better outcomes in patients with pstage II and III CRC after curative resection.

Objectives

This study evaluated the effect of particle size and dosage of granular activated carbon (GAC) on methane production from the anaerobic digestion of raw effluent (RE) of swine wastewater, and the solid (SF) and liquid (LF) fractions. The effect of temperature using the selected size and dosage of GAC was also evaluated.

Methods

60 mL of swine wastewater were inoculated with anaerobic granular sludge and GAC at different dosages and particle size. The cultures were incubated at different temperatures at 130 rpm. The kinetic parameters from experimental data were obtained using the Gompertz model.

Results

The cultures with the LF and GAC (75–150 μm, 15 g/L) increased 1.87-fold the methane production compared to the control without GAC. The GAC at 75–150 μm showed lower lag phases and higher R_max than the cultures with GAC at 590–600 μm. The cumulative methane production at 45 °C with the RE + GAC was 7.4-fold higher than the control. Moreover, methane production at 45 °C significantly increased with the cultures LF + GAC (6.0-fold) and SF + GAC (2.0-fold). The highest production of volatile fatty acids and ammonium was obtained at 45 °C regardless of the substrate and the addition of GAC contributed to a higher extent than the cultures lacking GAC. In most cases, the kinetic parameters at 30 °C and 37 °C were also higher with GAC.

Conclusions

GAC contributed to improving the fermentative and methanogenesis stages during the anaerobic digestion of fractions, evidenced by an improvement in the kinetic parameters.

Objective

Clostridium perfringens causes food poisoning and gas gangrene, a serious wound-associated infection. C. perfringens cells adhere to collagen via fibronectin (Fn). We thought that C. perfringens cells have some kind of Fn receptor. We investigated whether the peptidoglycan hydrolase of C. perfringens, i.e., autolysin (Acp), is implicated in Fn binding to C. perfringens cells.

Methods

This study used recombinant Acp fragments, human Fn and knockout mutants (C. perfringens 13 acp::erm and HN13 ΔfbpC ΔfbpD). Ligand blotting, Western blotting analysis, and complementation tests were performed. The Fn-binding activity of each mutant was evaluated by ELISA.

Results

From an Fn-binding assay using recombinant Acp fragments, Fn was found to bind to the catalytic domain of Acp. In mutant cells lacking Acp, Fn binding was significantly decreased, but was restored by the complementation of the acp gene. There are three known kinds of Fn-binding proteins in C. perfringens: FbpC, FbpD, and glyceraldehyde-3-phosphate dehydrogenase. We found no difference in Fn-binding activity between the mutant cells lacking both FbpC and FbpD (SAK3 cells) and the wild-type cells, indicating that these Fn-binding proteins are not involved in Fn binding to C. perfringens cells.

Conclusions

We found that the Acp is an Fn-binding protein that acts as an Fn receptor on the surface of C. perfringens cells.

The gut is host to a diverse array of microbiota that constitute a complex ecological system crucial to human physiology. Disruptors to the normal host microbiota, such as antimicrobials, can cause a loss of species diversity in the gut, reducing its ability to resist colonization by invading pathogens and potentially leading to colonization with antimicrobial resistant organisms (AROs). ARO negatively impact gut health by disrupting the usual heterogeneity of gut microbiota and have the potential to cause systemic disease. In recent years, fecal microbiota transplantation (FMT) has been increasingly explored in the management of specific disease states such as Clostridioides difficile infection (CDI). Promising data from management of CDI has led to considerable interest in understanding the role of therapeutics to restore the gut microbiota to a healthy state. This review aims to discuss key studies that highlight the current landscape, and explore existing clinical evidence, for the use of FMT and microbiome-based therapeutics in combating intestinal colonization with ARO. We also explore potential future directions of such therapeutics and discuss unaddressed needs in this field that merit further investigation.

Introduction

Lemierre syndrome is a thromboembolic complication following an acute bacterial infection of the head/neck area, often due to anaerobes. Data on the prognostic role of laboratory parameters is lacking.

Methods

We analyzed individual-patient level data from a multinational cohort of patients with Lemierre-syndrome. Patients had an infection in the head/neck area, and contiguous vein thrombosis or septic embolism, irrespective of the causal pathogen. We studied the patterns of white blood cell count, platelet count, and C-reactive protein concentration investigating their association with baseline characteristics and in-hospital clinical outcomes (septic embolism, major bleeding, all-cause death).

Results

A total of 447 (63%) patients had complete data for analysis. White blood cells were elevated across all subgroups (median 17 × 10³/μL; Q1-Q3:12-21). Median platelet count was 61 × 10³/μL (Q1-Q3:30-108) with decreasing levels with increasing age. Males, patients with renal failure or cardiopulmonary impairment, and those with typical Lemierre syndrome (tonsillitis, septic thromboembolism, positivity for Fusobacterium spp.) had the lowest platelet count. Median C-reactive protein was 122 (Q1-Q3:27-248) mg/L with higher values in patients who also had more severe thrombocytopenia. The overall risk of complications was similar across subgroups of patients stratified according to white blood cell and C-reactive protein levels. Patients in the lowest third of platelet count (<42 × 10³/μL) had the highest rate of complications (26%), as opposed to those in the highest third (11%), notably septic embolic events.

Conclusions

Common laboratory tests correlate with the clinical presentation of Lemierre syndrome. However, extreme values did not appear to be prognostically relevant for in-hospital complications and potentially able to improve clinical management.

We describe Tn7563, a 31,844-bp integrative and conjugative element (ICE) carrying promoters upregulating the cfiA carbapenemase gene in Bacteroides fragilis strain Tbg-22. Excision and circularization of Tn7563 was demonstrated by PCR. Previously, only insertion sequences (IS) have been shown to carry mobile promoters for cfiA.

Clostridium innocuum is a Gram-positive anaerobic spore-forming bacillus that has been identified as part of the normal intestinal microbiota. This bacterium has been rarely associated with human infections, and only few severe infections have been reported until now. In this work, we report on four patients with bacteremia due to C. innocuum, which were well identified by MALDI-TOF MS. Moreover, a review of the previous published cases of bacteremia due to this anaerobic bacterium has been performed.

Objective

Characterization and documentation of strain MCM B-1480^T, a novel sulfate-reducing bacterium isolated from produced water of India's western offshore hydrocarbon reservoir.

Method

Strain MCM B-1480^T was unequivocally identified using a polyphasic approach routinely followed in bacterial systematics. The morphological and biochemical characterization of strain MCM B-1480^T was carried out using standard microbiological techniques.

Results

MCM B-1480^T was a Gram-stain-negative, motile, non-spore-forming, curved-rod-shaped bacterium. MCM B-1480^T could grow at temperatures between 20 and 60 °C (optimum 37 °C), pH 6–8 (optimum 7), and required 1–6% NaCl (optimum 3%) for growth. Strain MCM B-1480^T was reducing sulfate to produce hydrogen sulfide during growth. This strain used lactate and pyruvate as prominent electron donors, whereas sulfate, sulfite, thiosulfate, and nitrate served as electron acceptors. MCM B-1480^T shared maximum 16S rRNA gene sequence homology of 98.65% with the members of the genus Pseudodesulfovibrio. The G + C content of the 3.87 Mb MCM B-1480^T genome was 60.39%. Digital DDH (27.7%) and average nucleotide identity (ANI 84%) with the closest phylogenetic affiliate (less than 70% and 95%, respectively) reaffirmed its distinctiveness. The major cellular fatty acids components, namely iso-C_15:0, anteiso-C_15:0, C_16:0, and anteiso-C_17:0, differentiated strain MCM B-1480^T from other species of Pseudodesulfovibrio. Genome annotation revealed the presence of genes encoding dissimilatory sulfate reduction and nitrate reduction in strain MCM B-1480^T.

Conclusion

The polyphasic studies, including SSU rRNA gene sequencing, average nucleotide identity, Digital DNA-DNA hybridization, cell wall fatty acids analysis, etc., identified strain MCM B-1480^T as a novel taxon and Pseudodesulfovibrio thermohalotolerans sp. nov. was proposed (= JCM 39269^T = MCC 4711^T).

Objectives

A better understanding of host-microbe interactions as a cross-talk between the gastrointestinal (GI) tract and the gut microbiota can help treat and prevent GI disorders by improving the maintenance of GI homeostasis. The gut microbiota can affect signaling molecules, such as serotonin, which regulates endocrine systems through the GI tract. Moreover, studying the effects of gut microbiota in the small intestine on the human GI tract health is pivotal.

Methods

Male C57BL/6J mice (n = 30, 10 mice per group) were orally gavaged with 200 μL of PBS (control group); mice in group II were orally gavaged with 109 colony-forming units (CFU)/200 μL of viable A. muciniphila, suspended in PBS (A. muciniphila group); and mice in group III were orally gavaged with 10 μg of protein/200 μL of EVs (A. muciniphila-EV group) once daily for four weeks. The gene expression of serotonin system-related genes (Slc6a4, Tph1, Mao, Htr3, Htr4, and Htr7) was examined by quantitative real-time PCR (qPCR) method.

Results

Based on the results, A. muciniphila significantly affected the mRNA expression of genes related to the serotonin system (Tph1, Mao, Htr3B, and Htr7) in the duodenum and (Htr3B, Htr4 and Htr7) in the ileum of mice (P < 0.05). Moreover, A. muciniphila-derived EVs affected the expression of major genes related to the serotonin system (Tph1, slc6a4a, Mao, Htr3B, Htr4, and Htr7) in the duodenum and ileum of mice (P < 0.05).

Conclusions

The present findings may pave the way for further investigation of the effects of strain-specific probiotics on the serotonergic system, which is currently in its infancy.

Clostridioides difficile infections (CDI) have a high morbidity and mortality rate and have always been considered a nosocomial disease. Nonetheless, the number of cases of community-acquired CDI is increasing, and new evidence suggests additional C. difficile reservoirs exist. Pathogenic C. difficile strains have been found in livestock, domestic animals, and meat, so a zoonotic transmission has been proposed.

Objective

The goal of this study was to isolate C. difficile strains in dogs at a veterinary clinic in Rio de Janeiro, Brazil, and characterize clinical and pathological findings associated with lower gastrointestinal tract disorders.

Methods

Fifty stool samples and biopsy fragments from dogs were obtained and cultured in the CDBA selective medium. All suggestive C. difficile colonies were confirmed by MALDI-TOF MS and PCR (tpi gene). Vancomycin, metronidazole, moxifloxacin, erythromycin, and rifampicin were tested for antibiotic susceptibility. Biofilm, motility assays, and a PCR for the toxins (tcdA, tcdB, and cdtB), as well as ribotyping, were also performed.

Results

Blood samples and colonic biopsy fragments were examined in C. difficile positive dogs. Ten animals (20%) tested positive for C. difficile by using stool samples, but not from biopsy fragments. Most C. difficile strains were toxigenic: six were A+B+ belonging to RT106; two were A+B+ belonging to RT014/020; and two were A-B- belonging to RT010. All strains were biofilm producers. In the motility test, 40% of strains were as motile as the positive control, CD630 (RT012). In the disc diffusion test, two strains (RT010) were resistant to erythromycin and metronidazole; and another to metronidazole (RT014/020). In terms of C. difficile clinicopathological correlations, no statistically significant morphological changes, such as pseudomembranous and "volcano" lesions, were observed. Regarding hematological data, dogs positive for C. difficile had leucopenia (p = 0.02) and lymphopenia (p = 0.03). There was a significant correlation between senility and the presence of C. difficile in the dogs studied (p = 0,02).

Conclusions

Although C. difficile has not been linked to canine diarrheal disorders, it appears to be more common in dogs with intestinal dysfunctions. The isolation of ribotypes frequently involved in human CDI outbreaks around the world supports the theory of C. difficile zoonotic transmission.