Anaerobe最新文献

Parvimonas micra is a gram-positive coccus which is an obligate anaerobe. It is a commensal in the oropharyngeal cavity and the gastrointestinal tract. The genus Parvimonas has only a single species, P. micra. Although there are several reports of infections due to P. micra involving various body sites, cases of brain abscess due to this organism have been under-reported in the literature. Here we present a rare case of cerebellar abscess caused by P. micra in a nine-year-old boy with complex cyanotic heart disease.

Objectives: The microaerophilic conditions in the large intestine and reactive oxygen species (ROS) produced by the immune system represent a challenge for the strictly anaerobic pathogen Clostridioides difficile, which protects itself by a variety of oxidative stress proteins. Four of these are encoded in an operon that has been implicated in the detoxification of H₂O₂ and O₂^●-. In this study, proteins of this operon, i. e. a rubrerythrin (Rbr), a superoxide reductase (Sor) and a putative glutamate dehydrogenase (CD630_08280) were investigated for their ROS detoxifying activity in vitro.

Methods: Recombinant proteins were overexpressed in C. difficile and purified anaerobically by affinity chromatography. The H₂O₂-reductase activity was determined by measuring the NADH consumption after peroxide addition. Superoxide detoxification potential of Sor was detected colorimetrically using a xanthine/xanthine oxidase system with cytochrome c as analytical probe.

Results: Proposed roles of the investigated proteins in the detoxification pathways of ROS could partially be demonstrated. Specifically, Rbr and glutamate dehydrogenase synergistically detoxify H₂O₂, although with a very low turnover. Furthermore, Sor was shown to scavenge O₂^●- by superoxide dismutase activity and its activity compared to superoxide dismutase of Escherichia coli.

Conclusions: The investigated gene locus codes for an oxidative stress operon whose members have the potential to neutralize O₂^●- and H₂O₂ to water and thus complements the arsenal of ROS detoxifying mechanisms that are already known in C. difficile. However, full activity with adequate physiological electron transfer partners still needs to be demonstrated.

Objectives: Clostridium butyricum ferments non-digested dietary fibre in the colon to produce butyric acid. Butyrate is a four-carbon, short-chain fatty acid (SCFA) which has multiple health benefits. Many microbial products of pharmaceutical or industrial interest, such as butyrate, are produced in low quantities due to rate-limiting steps in their metabolic pathway, including low abundance or low activity of one or more enzymes in the pathway. By identifying the former, appropriate enzymes can be over-expressed to increase product yields, however, methods to determine these enzymes are laborious. To improve butyrate production in C. butyricum probiotic strain, CBM588, a novel rapid genome-proteome approach was deployed.

Methods: First, whole genome sequencing was performed and the 8 genes involved in butyrate production identified on the chromosome. Second, the relative abundance of these enzymes was investigated by liquid chromatography-mass spectrometry (LC-MS) analysis of total cytosolic proteins from early stationary phase cultures.

Results: Phosphotransbutyrylase (Ptb), butyrate kinase (Buk) and crotonase (Crt) were found to be the least abundant. Over-expression episomally of the corresponding genes individually or of the ptb-buk bicistron led to significant increases in butyrate titre per density of culture from 10 to 24 hours, compared to the wild type.

Conclusions: Our findings pave the way for over-expressing these genes chromosomally to generate a recombinant probiotic with improved butyrate production and potentially enhanced gut health properties.

Clostridioides (Clostridium) difficile (C. difficile) infection (CDI), often severe when producing toxin A, toxin B, and CDT, can cause life-threatening fulminant infections, especially in vulnerable patients. This case report discusses a 39-year-old woman with no medical history who developed severe CDI after antibiotic treatment, leading to fatal hypovolemic shock. A rare C. difficile PCR-ribotype 153 strain which is positive for toxin A, toxin B, and CDT was identified. This case emphasizes the need for early CDI diagnosis, cautious antibiotic use, and prompt treatment to prevent severe outcomes like shock and multiorgan failure.