Butyricimonas virosa: A rare cause of bacteremia

Butyricimonas faecihominis: an atypically resistant bacterium implicated in abscess formation - a case report

BACKGROUND

This case report presents a unique instance of abscesses with an uncommon pathogen isolated from blood cultures.

CASE PRESENTATION

We present the case of a perianal abscess in a 50-year-old man with a history of cocaine abuse and bilateral hip replacements. The rapid progression led to septic shock and multi-organ failure, requiring intensive care unit admission, surgery including protective transversostomy. Blood cultures showed growth of Butyricimonas spp. with resistance to penicillin and piperacillin-tazobactam. The immediate switch to meropenem led to a significant improvement in the patient's condition. The patient was discharged after 40 days of hospitalization in good general condition and the reversal of the transversostomy was performed six months later.

CONCLUSION

The identification of Butyricimonas faecihominis, a rarely reported pathogen, emphasizes the challenges of diagnosing and treating unusual infections. This case emphasizes the importance of rapid microbiological diagnosis, interdisciplinary collaboration, and targeted antibiotic therapy in the treatment of abscesses and sepsis.

Purple sweet potato anthocyanins normalize the blood glucose concentration and restore the gut microbiota in mice with type 2 diabetes mellitus

Background

This study investigated the effects of purple sweet potato anthocyanins (PSPA) in a type 2 diabetes mellitus (T2DM) mouse model.

Methods

Sixty-five male mice were randomly divided into one control group and four experimental groups, which were fed with a high-fat diet and intraperitoneally injected with streptozotocin (STZ) to induce T2DM. The model mice were treated with 0 (M), 227.5 (LP), 455 (MP), or 910 (HP) mg/kg PSPA for ten days. ELISA, 16S rRNA sequencing, and hematoxylin and eosin staining were used to assess blood biochemical parameters, gut microbial composition, and liver tissue structure, respectively.

Results

The FBG concentration was significantly decreased in the LP (6.32 ± 1.05 mmol/L), MP (6.32 ± 1.05 mmol/L), and HP (5.65 ± 0.83 mmol/L) groups; the glycosylated hemoglobin levels were significantly decreased in the HP group (14.43 ± 7.12 pg/mL) compared with that in the M group (8.08 ± 1.04 mmol/L; 27.20 ± 7.72 pg/mL; P < 0.05). The PSPA treated groups also increased blood glutathione levels compared with M. PSPA significantly affected gut microbial diversity. The Firmicutes/Bacteroidetes ratio decreased by 38.9 %, 49.2 %, and 15.9 % in the LP, MP, and HP groups compared with that in the M group (0.62). The PSPAs treated groups showed an increased relative abundance of Lachnospiraceae_Clostridium, Butyricimonas, and Akkermansia and decreased abundance of nine bacterial genera, including Staphylococcus.

Conclusion

PSPA reduced blood glucose levels, increased serum antioxidant enzymes, and optimized the diversity and structure of the gut microbiota in mice with T2DM.

Effects of iodoacetic acid drinking water disinfection byproduct on the gut microbiota and its metabolism in rats

Iodoacetic acid (IAA) is an unregulated disinfection byproduct in drinking water and has been shown to exert cytotoxicity, genotoxicity, tumorigenicity, and reproductive and developmental toxicity. However, the effects of IAA on gut microbiota and its metabolism are still unknown, especially the association between gut microbiota and the metabolism and toxicity of IAA. In this study, female and male Sprague-Dawley rats were exposed to IAA at 0 and 16 mg/kg bw/day daily for 8 weeks by oral gavage. Results of 16S rRNA gene sequencing showed that IAA could alter the diversity, relative abundance and function of gut microbiota in female and male rats. IAA also increased the abundance of genes related to steroid hormone biosynthesis in the gut microbiota of male rats. Moreover, metabolomics profiling revealed that IAA could significantly disturb 6 and 13 metabolites in the feces of female and male rats, respectively. In female rats, the level of androstanediol increased in the IAA treatment group. These results were consistent with our previous findings, where IAA was identified as an androgen disruptor. Additionally, the perturbed gut microbiota and altered metabolites were correlated with each other. The results of this study indicated that IAA could disturb gut microbiota and its metabolism. These changes in gut microbiota and its metabolism were associated with the reproductive and developmental toxicity of IAA.

2'-Fucosyllactose Ameliorates Oxidative Stress Damage in d-Galactose-Induced Aging Mice by Regulating Gut Microbiota and AMPK/SIRT1/FOXO1 Pathway

The imbalance of reactive oxygen species is the main cause in aging, accompanied by oxidative stress. As the most abundant in human milk oligosaccharides (HMOs), 2′-Fucosyllactose (2′-FL) has been confirmed to have great properties in immunity regulation and anti-inflammatory. The research on 2′-FL is focused on infants currently, while there is no related report of 2′-FL for the elderly. A d-galactose-induced accelerated aging model was established to explore the protective effect of 2′-FL on the intestines and brain in mice. In this study, 2′-FL significantly reduced oxidative stress damage and inflammation in the intestines of aging mice, potentially by regulating the sirtuin1 (SIRT1)-related and nuclear factor E2-related factor 2 (Nrf2) pathways. In addition, 2′-FL significantly improved the gut mucosal barrier function and increased the content of short-chain fatty acids (SCFAs) in the intestine. The gut microbiota analysis indicated that 2′-FL mainly increased the abundance of probiotics like Akkermansia in aging mice. Moreover, 2′-FL significantly inhibited apoptosis in the brains of aging mice, also increasing the expression of SIRT1. These findings provided a basis for learning the benefits of 2′-FL in the aging process.

Gut Microbial Signatures for Glycemic Responses of GLP-1 Receptor Agonists in Type 2 Diabetic Patients: A Pilot Study

BACKGROUNDS

Glucagon-like peptide-1 receptor agonist (GLP-1 RA) is probably one of more effective antidiabetic agents in treatment of type 2 diabetes mellitus (T2D). However, the heterogenicity in responses to GLP-1 RA may be potentially related to gut microbiota, although no human evidence has been published. This pilot study aims to identify microbial signatures associated with glycemic responses to GLP-1 RA.

MATERIALS AND METHODS

Microbial compositions of 52 patients with T2D receiving GLP-1 RA were determined by 16S rRNA amplicon sequencing. Bacterial biodiversity was compared between responders versus non-responders. Pearson's correlation and random forest tree algorithm were used to identify microbial features of glycemic responses in T2D patients and multivariable linear regression models were used to validate clinical relevance.

RESULTS

Beta diversity significantly differed between GLP-1 RA responders (n = 34) and non-responders (n = 18) (ADONIS, P = 0.004). The top 17 features associated with glycohemoglobin reduction had a 0.96 diagnostic ability, based on area under the ROC curve: Bacteroides dorei and Roseburia inulinivorans, the two microbes having immunomodulation effects, along with Lachnoclostridium sp. and Butyricicoccus sp., were positively correlated with glycemic reduction; Prevotella copri, the microbe related to insulin resistance, together with Ruminococcaceae sp., Bacteroidales sp., Eubacterium coprostanoligenes sp., Dialister succinatiphilus, Alistipes obesi, Mitsuokella spp., Butyricimonas virosa, Moryella sp., and Lactobacillus mucosae had negative correlation. Furthermore, Bacteroides dorei, Lachnoclostridium sp. and Mitsuokella multacida were significant after adjusting for baseline glycohemoglobin and C-peptide concentrations, two clinical confounders.

CONCLUSIONS

Unique gut microbial signatures are associated with glycemic responses to GLP-RA treatment and reflect degrees of dysbiosis in T2D patients.

A subcutaneous infection mimicking necrotizing fasciitis due to Butyricimonas virosa

INTRODUCTION

Butyricimonas virosa is a Gram-negative rod who was first identified in rat faces in 2009. Since then only six human infections have been described in literature of which five bacteremia and one bone abscess. We report a clinical case of a subcutaneous infection mimicking necrotizing fasciitis due to B. virosa.

PATIENT AND METHODS

A 78-year-old man was referred to our hospital because of a wound infection at the surgical site with suspicion of necrotizing fasciitis. Treatment consisted of immediate surgical exploration with obtainment of intra-operative specimens for microbiologic examination, 15 d of negative pressure wound therapy (NPWT) and antibiotic treatment with piperacillin-tazobactam (12 d) plus vancomycin (9 d).

RESULTS

Surgical exploration did not show necrotising fasciitis but a subcutaneous infection mimicking necrotising fasciitis. The results of the intra-operative specimens revealed the presence of B.virosa and Finegoldia magna. Cultures taken during the NPWT replacements became negative and the patient was able to leave the hospital after 18 d.

CONCLUSIONS

Considering there was no necrotizing infection present it may have been possible to safely close the wound sooner. However, it is difficult to differentiate between an actual necrotizing fasciitis and a subcutaneous infection mimicking necrotizing fasciitis. Therefore further studies on effective assessment tools to diagnose necrotizing fasciitis, such as the (modified) laboratory risk indicator for necrotizing fasciitis (LRINEC) score and enhanced computed tomography (CT), could be helpful.

Granulocyte-macrophage colony-stimulating factor protects mice against hepatocellular carcinoma by ameliorating intestinal dysbiosis and attenuating inflammation

BACKGROUND

Hepatocellular carcinoma (HCC) is the third leading cause of cancer mortality worldwide. The gut microbiota can help maintain healthy metabolism and immunity. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a critical factor in promoting health and homeostasis; it promotes intestinal immunity, stimulates bone marrow precursors to generate macrophage colonies, and enhances the antibacterial and antitumor activity of circulating monocytes. As such, GM-CSF may protect against HCC development by regulating immunity as well as intestinal microecology.

AIM

To investigate the impact of GM-CSF on the gut microbiome and metabolic characteristics of HCC.

METHODS

Thirty-six male BALB/c nude mice were divided into three groups: Control (n = 10), HCC (n = 13), and HCC + GM-CSF (GM-CSF overexpression, n = 13). We utilized HCC cells to establish orthotopic transplantation tumor models of HCC with normal and over-expressing GM-CSF. Liver injury, immune inflammatory function and intestinal barrier function were evaluated. The fecal microbiome and metabolome were studied using 16S rRNA absolute quantification sequencing and gas chromatography-mass spectrometry.

RESULTS

GM-CSF overexpression significantly affected the gut microbiome of mice with HCC and resulted in a high abundance of organisms of the genera Roseburia, Blautia and Butyricimonass, along with a significant reduction in Prevotella, Parabacteroides, Anaerotruncus, Streptococcus, Clostridium, and Mucispirillum. Likewise, GM-CSF overexpression resulted in a substantial increase in fecal biotin and oleic acid levels, along with a prominent decrease in the fecal succinic acid, adenosine, fumaric acid, lipoic acid, and maleic acid levels. Correlation analysis revealed that the intestinal microbiota and fecal metabolites induced by GM-CSF were primarily involved in pathways related to reducing the inflammatory response, biotin metabolism, and intestinal barrier dysfunction.

CONCLUSION

GM-CSF can protect against HCC development by regulating immunity and modulating the abundance of specific intestinal microorganisms and their metabolites. This study provides new insights into the therapeutic approaches for HCC.

Relevance of anaerobic bacteremia in adult patients: A never-ending story?

Obligate anaerobic bacteria are considered important constituents of the microbiota of humans; in addition, they are also important etiological agents in some focal or invasive infections and bacteremia with a high level of mortality. Conflicting data have accumulated over the last decades regarding the extent in which these pathogens play an intrinsic role in bloodstream infections. Clinical characteristics of anaerobic bloodstream infections do not differ from bacteremia caused by other pathogens, but due to their longer generation time and rigorous growth requirements, it usually takes longer to establish the etiological diagnosis. The introduction of matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) has represented a technological revolution in microbiological diagnostics, which has allowed for the fast, accurate and reliable identification of anaerobic bacteria at a low sample cost. The purpose of this review article is to summarize the currently available literature data on the prevalence of anaerobic bacteremia in adults for physicians and clinical microbiologists and to shed some light on the complexity of this topic nowadays.

Changes in the gut microbiota during and after commercial helium–oxygen saturation diving in China

Objectives

The influence of commercial helium–oxygen saturation diving on divers’ gut microbiotas was assessed to provide dietary suggestion.

Methods

Faecal samples of 47 divers working offshore were collected before (T1), during (T2) and after (T3) saturation diving. Their living and excursion depths were 55–134 metres underwater with a saturation duration of 12–31 days and PaO2 of 38–65 kPa. The faecal samples were examined through 16S ribosomal DNA amplicon sequencing based on the Illumina sequencing platform to analyse changes in the bacteria composition in the divers’ guts.

Results

Although the α and β diversity of the gut microbiota did not change significantly, we found that living in a hyperbaric environment of helium–oxygen saturation decreased the abundance of the genus Bifidobacterium, an obligate anaerobe, from 2.43%±3.83% at T1 to 0.79%±1.23% at T2 and 0.59%±0.79% at T3. Additionally, the abundance of some short-chain fatty acid (SCFA)-producing bacteria, such as Fusicatenibacter, Faecalibacterium, rectale group and Anaerostipes, showed a decreased trend in the order of before, during and after diving. On the contrary, the abundance of species, such as Lactococcus garvieae, Actinomyces odontolyticus, Peptoclostridium difficile, Butyricimonas virosa, Streptococcus mutans, Porphyromonas asaccharolytica and A. graevenitzii, showed an increasing trend, but most of them were pathogens.

Conclusions

Occupational exposure to high pressure in a helium–oxygen saturation environment decreased the abundance of Bifidobacterium and some SCFA-producing bacteria, and increased the risk of pathogenic bacterial infection. Supplementation of the diver diet with probiotics or prebiotics during saturation diving might prevent these undesirable changes.