Anaerobe最新文献

Clostridium perfingens bloodstream infections (BSIs) can be associated with high mortality rates. We performed a subanalysis of all C. perfringens BSIs enrolled during a multicentric retrospective observational study (ITANAEROBY). Data were collected from January 2016 to December 2020. C. perfringens BSIs were 134 (134/1960, 6.8 %). The highest resistance rate was observed for clindamycin (26/120, 21.6 %), penicillin (11/71, 15.4 %) and metronidazole (14/131, 10.7 %). In conclusion, C. perfringens reduced susceptibility phenotype to first-line therapy.

Introduction

Chickens with Necrotic Enteritis (NE), caused by Clostridium perfringens, exhibit acute and chronic symptoms that are difficult to diagnose, leading to significant economic losses. Vaccination is the best method for controlling and preventing NE. However, only two vaccines based on the CPA and NetB toxins have been commercialized, offering partial protection, highlighting the urgent need for more effective vaccines.

Objective

This review aimed to identify promising antigens for NE vaccine formulation and discuss factors affecting their effectiveness.

Methods

A systematic review using five scientific databases identified 30 eligible studies through the Rayyan tool, which were included for quality review.

Results

We identified 25 promising antigens, including CPA, NetB, FBA, ZMP, CnaA, FimA, and FimB, categorized by their role in disease pathogenesis. This review discusses the biochemical, physiological, and genetic traits of recombinant antigens used in vaccine prototypes, their expression systems, and immunization potential in chickens challenged with virulent C. perfringens strains. Market supply challenges, immunogenic potential, vaccine platforms, adjuvants, and factors related to vaccination schedules—such as administration routes, dosing intervals, and age at immunization—are also addressed. Additionally, the study notes that vaccine formulations tested under mild challenges may not offer adequate field-level protection due to issues replicating aggressive conditions, strain virulence loss, and varied methodologies.

Conclusions

An ideal NE vaccine should incorporate multiple antigens, molecular adjuvants, and delivery systems via in ovo and oral routes. The review underscores the challenges in developing and validating NE vaccines and the urgent need for a standardized protocol to replicate aggressive challenges accurately.

Objectives

This study investigated the codigestion of corn straw (CS) with cow manure (CM), cow digestion solution (CD), and a strain consortium (SC) for enhanced volatile fatty acid (VFA) production. The aims of this study were to develop a sustainable technique to increase VFA yields, examine how combining microbial reagents with CS affects VFA production by functional microorganisms, and assess the feasibility of improving microbial diversity through codigestion.

Methods

Batch experiments evaluated VFA production dynamics and microbial community changes with different combinations of CS substrates with CM, CD, and SC. Analytical methods included measuring VFAs by GC, ammonia and chemical oxygen demand (COD) by standard methods and microbial community analysis by 16S rRNA gene sequencing.

Results

Codigesting CS with the strain consortium yielded initial VFA concentrations ranging from 0.6 to 1.0 g/L, which were greater than those of the other combinations (0.05–0.3 g/L). Including CM, and CD further increased VFA production to 1.0–2.0 g/L, with the highest value of 2.0 g/L occurring when all four substrates were codigested. Significant ammonium reduction (194–241 mg/L to 29–37 mg/L) and COD reduction (3310–5250 mg/L to 730–1210 mg/L) were observed. Codigestion with CM and CD had greater Shannon diversity indices (3.19–3.24) than did codigestion with the other consortia (2.26). Bacillota dominated (96.5–99.6 %), with Clostridiales playing key roles in organic matter breakdown.

Conclusions

This study demonstrated the feasibility of improving VFA yields and harnessing microbial diversity through anaerobic codigestion of lignocellulosic and animal waste streams. Codigestion substantially enhanced VFA production, which was dominated by butyrate, reduced ammonium and COD, and enriched fiber-degrading and fermentative bacteria. These findings can help optimize codigestion for sustainable waste management and high-value chemical production.

Oxygen tolerance of anaerobes is a virulence factor, but can also be a beneficial property. Many species have evolved to tolerate or take advantage of the presence of low, especially nanaerobic (≤0.14 %) oxygen concentrations. Oxygen tolerance is genus-, species- and strain-dependent according to their protective mechanisms. It was better expressed in some pathogenic species such as Bacteroides fragilis, Clostridioides difficile, and Clostridium perfringens, as well as in Akkermansia muciniphila than in other potential probiotics such as Alistipes, Blautia and Roseburia spp. Different degrees of oxygen sensitivity were found between the strains of Anaerostipes, Faecalibacterium, and Bifidobacterium spp. Importantly, clostridial spores and anaerobes in biofilms are protected from oxidation. Rubrerythrins and flavodiiron proteins and two regulators (sigma factor B and PerR) contribute to C. difficile protection from reactive oxygen species (ROS). The frequent pathogen, B. fragilis, has numerous protective factors such as enzymes (catalase, superoxide dismutase, alkyl hydroperoxidase, thioredoxin peroxidase, and aerobic-type NrdAB ribonucleotide reductase), and nanaerobic respiration. Seven proteins confer strain-specific oxygen adaptation of Faecalibacterium prausnitzii. Oxygen tolerance protects anaerobes from ROS, shields their DNA and modulates gene expression. Furthermore, oxygen can induce mutations leading to antibiotic resistance as shown in Prevotella melaninogenica. Some Faecalibacterium, Anaerostipes, Bifidobacterium, and Akkermansia strains from the intestinal microbiota exhibiting oxygen tolerance may become next-generation probiotic candidates. Further studies are needed to reveal oxygen effects on more anaerobic species and strains, and the influence of oxygen on antibiotic resistance. More studies on oxygen-tolerant probiotic strains can be useful to optimize biotechnological methods.

Objectives

Bacteremia with anaerobic bacteria is generally a marker of severe prognosis. However, population-based data is lacking. Our aim was to describe the epidemiology and the 30-day mortality rate of anaerobic bacteremia in a Danish population-based setting.

Methods

In this population-based cohort study, all first-time episodes of anaerobic bacteremia from the North Denmark Bacteremia Research Database during 1994–2019 were identified. Information on comorbidities, discharge diagnoses, and mortality was retrieved. 30-day mortality rates were calculated and a multivariate logistic regression analysis to identify risk factors for death was performed.

Results

1750 episodes with anaerobic bacteremia were identified, corresponding to an incidence rate of 12.5 per 100,000 inhabitants (increasing from 11.2 in 1994–2014 to 17.7 in 2015–2019). Of these episodes, a third were polymicrobial, and the majority (70 %) of patients had one or more comorbid conditions. Abdominal infection was the source of bacteremia in 61 % of patients, while it was unknown for 15 %. The most frequently isolated genera were Bacteroides (45 %), Clostridium (20 %) and Fusobacterium (6 %). The overall crude 30-day mortality rate was 27 %, but rates were even higher for patients of high age, with liver disease, and solid tumors. The odds ratio (OR) for 30-day mortality was 1.32 for Clostridium species, and 1.27 for polymicrobial bacteremia with aerobic bacteria.

Conclusions

The incidence rate of anaerobic bacteremia increased, and the 30-day mortality rate remained high during the study period. Multiple factors influence 30-day mortality rates, including high age, liver disease, solid tumor, polymicrobial bacteremia, and bacteremia with Clostridium species.

Objective

Flagellin protein, an integral component of flagella, provides motility to several bacterial species and also acts as a candidate antigen in diagnostics and subunit vaccines. The bulk production of flagellin with retention of all conformational epitopes using recombinant protein technology is of paramount importance in the development of pathogen-specific immuno-assays and vaccines. We describe the production of highly soluble and immuno-reactive rFliA(C) protein of Clostridium chauvoei, a causative agent of blackleg or black quarter (BQ) affecting cattle and small ruminants worldwide. The bacterium is known to possess peritrichous flagella that provide motility and also act as a virulence factor with high protective antigenicity.

Methods

Upon sequence and structural analysis, a partial fliA(C) gene from Clostridium chauvoei was cloned and the recombinant mature protein with N- and C- terminal truncation was over-expressed as a His-tagged fusion protein (∼25 kDa) in Escherichia coli. Subsequently, rFliA(C) protein was purified by single-step affinity chromatography and characterized for its immuno-reactivity in laboratory animals, Western blot, and indirect-ELISA format.

Results

rFliA(C) was highly soluble and was purified in high quantity and quality. rFliA(C) elicited antigen-specific conformational polyclonal antibodies in rabbit and guinea pig models, as well as anti-Clostridium chauvoei-specific antibodies being specifically detected in BQ-vaccinated and convalescent sera of bovines in Western blot and in indirect-ELISA format. Further, no cross reactivity was noted with antibodies against major bovine diseases (e.g., foot-and-mouth disease, IBR, LSDV, hemorrhagic septicaemia, brucellosis, and leptospirosis).

Conclusion

The study indicated the production of conformational recombinant flagellin—rFliA(C)—antigen and its potential utility in development of diagnostics for detection of Clostridium chauvoei-specific antibodies in BQ-recovered and/or vaccinated animals.

Introduction

Producing commercial bacterins/toxoids against Clostridium spp. is laborious and hazardous. Conversely, developing prototype vaccines using purified recombinant toxoids, though safe and effective, is both laborious and costly for application in production animals.

Objective

Considering that inactivated recombinant Escherichia coli (bacterin) is a simple, cost-effective, and to be safe solution, we evaluated, for the first time, a pentavalent formulation of recombinant bacterins containing the alpha, beta, and epsilon toxins of Clostridium perfringens and C and D neurotoxins of Clostridium botulinum in sheep.

Methods

Subcutaneously, 18 Texel sheep received two doses (200 μg of each antigen) of recombinant bacterin (n = 7) or purified recombinant antigens (n = 6) on days 0 and 28, while the control group (n = 5) did not receive an immunization. Sera samples from days 0 (before the 1st dose), 28 (before the 2nd dose), and 56, 84, and 112 were used for measuring IgG (indirect ELISA) and neutralizing antibodies (mouse serum neutralization).

Results

Both formulations induced significant levels of IgG against all five toxins (p < 0.05) up to day 112, with peaks at days 28 and 56 post-immunization. The expected booster effect occurred only for the botulinum toxins. The neutralizing antibody titers were satisfactory against ETX (≥2 IU/ml for both formulations) and BoNT-D [5 IU/ml (bacterin) and 10 IU/ml (purified)].

Conclusion

While adjustments are required, the recombinant bacterin platform holds great potential for polyvalent vaccines due to its straightforward, safe, and cost-effective production, establishing it as a user-friendly technology for the veterinary immunobiological industry.

Objectives

Feeding winery by-products (WBP) could affect the bovine microbiome because of their phenol compounds and a transfer of WBP-associated microbiota. This work examined changes in the underexplored solid-associated rumen microbiome following the inclusion of WBP.

Methods

Using the rumen simulation technique, fermenters were inoculated with the inoculum of donor cows and were fed one of six dietary treatments including a control diet of 70 % hay +30 % concentrate (CON), control diet + 3.7 % commercial grapeseed extract (EXT), 65 % hay + 25 % concentrate + 10 % grape pomace (GP-low), 56 % hay + 24 % concentrate + 20 % grape pomace (GP-high), 70 % hay + 25 % concentrate + 5 % grapeseed meal (GS-low), and 65 % hay + 25 % concentrate + 10 % grapeseed meal (GS-high) (dry matter basis). The compositional changes of bacteria, archaea and fungi in the solid fractions were based on 16S and ITS2 rRNA sequencing.

Results

The alpha- and beta-diversity of the microbiota were unaffected. However, treatment modified the bacterial composition at low taxonomic levels. Butyrivibrio fibrisolvens, Treponema bryantii, and bacterium MC2010 decreased in EXT, while Treponema berlinense was increased in GP-high and GP-low compared to CON. Concerning fungi, GS-high increased Candida spp., Lachancea spp., Microdochium spp., Mucor spp., Pichia spp., Saturnispora spp., and Zygosaccharomyces spp. compared to CON. Many non-Saccharomyces yeasts were detected in WBP samples but absent in donor cows and CON samples. The genera affected by treatment were not the major contributors to the ruminal degradation of nutrients.

Conclusions

The results indicate a sensitivity of rumen solid bacteria to grape phenols when delivered as an extract and a transfer of WBP-associated microbiota into the rumen.