A new treatment of sepsis caused byveillonella parvula: A case report and literature review

Detecting and quantifying Veillonella by real-time quantitative PCR and droplet digital PCR

Veillonella spp. are Gram-negative opportunistic pathogens present in the respiratory, digestive, and reproductive tracts of mammals. An abnormal increase in Veillonella relative abundance in the body is closely associated with periodontitis, inflammatory bowel disease, urinary tract infections, and many other diseases. We designed a pair of primers and a probe based on the 16S rRNA gene sequences of Veillonella and conducted real-time quantitative PCR (qPCR) and droplet digital PCR (ddPCR) to quantify the abundance of Veillonella in fecal samples. These two methods were tested for specificity and sensitivity using simulated clinical samples. The sensitivity of qPCR was 100 copies/μL, allowing for the accurate detection of a wide range of Veillonella concentrations from 103 to 108 CFU/mL. The sensitivity of ddPCR was 11.3 copies/μL, only allowing for the accurate detection of Veillonella concentrations from 101 to 104 CFU/mL because of the limited number of droplets generated by ddPCR. ddPCR is therefore more suitable for the detection of low-abundance Veillonella samples. To characterize the validity of the assay system, clinical samples from children with inflammatory bowel disease were collected and analyzed, and the results were verified using isolation methods. We conclude that molecular assays targeting the 16S rRNA gene provides an important tool for the rapid diagnosis of chronic and infectious diseases caused by Veillonella and also supports the isolation and identification of Veillonella for research purposes. KEY POINTS: • With suitable primer sets, the qPCR has a wider detection range than ddPCR. • ddPCR is suitable for the detection of low-abundance samples. • Methods successfully guided the isolation of Veillonella in clinical sample.

Veillonella parvula as an anaerobic lactate-fermenting bacterium for inhibition of tumor growth and metastasis through tumor-specific colonization and decrease of tumor's lactate level

High tumor's lactate level directly associates with high tumor growth, metastasis, and patients' poor prognosis. Therefore, many studies have focused on the decrease of tumor's lactate as a novel cancer treatment. In the present study for the first time, a strictly anaerobic lactate-fermenting bacterium, Veillonella parvula, was employed for the decrease of tumor's lactate level. At first, 4T1 breast tumor-bearing BALB/c mice were administered with 106 V. parvula bacteria intravenously, orally, intraperitoneally, and intratumorally. Then, the bacteria biodistribution was evaluated. The best administration route according to tumor colonization was selected and its safety was assessed. Then, the therapeutic effect of V. parvula administration through the best route was investigated according to 4T1 murine breast tumor's growth and metastasis in vivo. In addition, histopathological and immunohistochemistry evaluations were done to estimate microscopic changes at the inner of the tumor and tumor's lactate level was measured after V. parvula administration. V. parvula exhibited considerable tumor-targeting and colonization efficacy, 24 h after intravenous administration. Normal organs were free of the bacteria after 72 h and no side effect was observed. Tumor colonization by V. parvula significantly decreased the tumors' lactate level for about 46% in comparison with control tumors which caused 44.3% and 51.6% decline (P < 0.05) in the mean tumors' volume and liver metastasis of the treatment group in comparison with the control group, respectively. The treatment group exhibited 35% inhibition in the cancer cell proliferation in comparison with the control according to the Ki-67 immunohistochemistry staining. Therefore, intravenous administration of V. parvula is a tumor-specific and safe treatment which can significantly inhibit tumors' growth and metastasis by decreasing the tumor lactate level.

Bacteremia caused by Veillonella parvula: Two case reports and a review of the literature

Veillonella parvula is a non-motile gram-negative coccus that forms part of the normal microbiota in several body sites and which has been rarely isolated as cause of infections in human population, particularly in bacteremias. Here we give the overview of characteristics of genus Veillonella and the summary of its role in infections, particularly in bacteremia. We additionally report two patients with bacteremia due to V. parvula. Two sets of blood cultures of each patient yielded a pure culture of an anaerobic microorganism identified as V. parvula by MALDI-TOF MS, and confirmed by 16S rRNA gene sequencing. The two patients were male and one of them had risk factors for anaerobic bacteremia. The isolates were susceptible to most antibiotics and the outcome was successful in both patients. Bacteremia due to V. parvula is still rare. MALDI-TOF MS appear to be an excellent tool for the correct identification of these species.

Veillonella Bacteremia in a Patient With Metastatic Colorectal Carcinoma

Colorectal carcinoma has increasingly been reported to be associated with gut microbial dysbiosis. Bacteroides, Fusobacterium, Faecalibacterium, Blautia, etc., are gut microbes commonly associated with colorectal carcinoma. Gut microbial dysregulation secondary to infectious, inflammatory, toxin exposure or change in dietary habits coupled with the disruption of the inner mucosal layer overlying the luminal epithelium is hypothesized as the inciting events leading to microbial invasion and subsequent tumorigenesis. Although the precise mechanism is unclear, disruption of normal host responses like inflammation, apoptosis, cellular proliferation, free radical injury, production of oncogenic toxins, etc., is postulated to play a role. We report a case of Veillonella bacteremia in a patient with metastatic colorectal carcinoma without a preceding history of periodontal disease. The patient was managed with ampicillin-sulbactam, which was followed by subsequent negative blood cultures. This case report signifies the association of gut microbiota like Veillonella with colorectal carcinoma and the importance of subsequent screening for colorectal cancer following Veillonella bacteremia.

Severe disseminated Veillonella parvula infection including endocarditis, bilateral psoas abscess, discitis, and osteomyelitis but sparing spinal and hip prostheses: a case report

Background

Veillonella species are an opportunistically pathogenic commensal anaerobic Gram-negative coccus commonly found in the oral, genitourinary, respiratory, and intestinal tract of humans and some animals. Infection is rare, even in immunocompromised hosts, and has been identified to cause a wide array of different infections, including endocarditis, osteomyelitis, and meningitis.

Case presentation

An 82-year-old Caucasian male retired ex-gymnast presented to the emergency department with a 2-week history of acute on chronic lower back pain without clear precipitant. He displayed no systemic symptoms, and had not sustained any recent injuries. Initial blood and radiological investigation did not reveal an infective or mechanical cause for his pain; however, a few days into admission, he developed a fever and signs of sepsis. A thorough septic screen was performed, including a spinal magnetic resonance imaging scan, which did not reveal any abnormalities. Blood cultures revealed Veillonella parvula bacteremia, with subsequently repeated magnetic resonance imaging displaying rapid disseminated infection including bilateral psoas abscess, discitis, and osteomyelitis. Infective endocarditis was later identified with echocardiogram. He received intravenous ceftriaxone and later oral amoxicillin and clavulanic and recovered on 6-month follow-up.

Conclusions

This case illustrates the potential pathogenicity and unexpected rapid course of Veillonella parvula infection even in an immunocompetent host presenting with back pain. This case highlights the critical importance of a thorough septic screen when investigating patients for early signs of sepsis.

Soybean diacylglycerol regulates lipid metabolism in D-galactose-induced aging rats by altering gut microbiota and gene expression of colonic epithelial cells

Lipid metabolism is closely related to the health of aging bodies and its disorder often leads to cardiovascular diseases and chronic diseases. Dietary fat is one of the important sources of body fat, which affects the body's lipid metabolism. However, how dietary fat affects lipid metabolism in aging bodies has not been reported. Thus, the effects of soybean diacylglycerol (DAG) on lipid metabolism in D-galactose-induced aging rats were investigated by detecting the serum biochemical indexes, hepatocyte morphology, gut microbiota changes, and gene expression of colonic epithelial cells. The results showed that DAG alleviated the lipid metabolism disorders, and the hepatocyte morphology of aging rats fed DAG was normal. 16S rDNA analysis showed that DAG restored Eisenbergiella and Veillonella that were missing in aging rats. The relative abundances of Romboutsia and Ruminococcus_2 decreased and the relative abundance of Lachnospiraceae NK4A136 group increased significantly with the influence of DAG (P < 0.05). Gene expression profiles showed that the gene expression of colon epithelial cells was altered by DAG and DAG downregulated the genes Lipe and Fabp4 related to the lipolysis of adipocytes. In conclusion, DAG regulated the lipid metabolism of aging rats by regulating gut microbiota and gene expression of colonic epithelial cells.

Retrospective Analysis of the Clinical Efficacy of Early Goal-Directed Therapy Combined with Meticulous Nursing Intervention in Patients with Posttraumatic Sepsis

Objective

To explore the intervention effect of early goal-directed therapy (EGDT) combined with meticulous nursing on patients with posttraumatic sepsis.

Methods

The data of 50 patients with posttraumatic sepsis undergoing EGDT in the emergency department of our hospital from January 2020 to December 2020 were retrospectively analyzed. According to different nursing methods, they were divided into control group (n = 25) with routine nursing measures and observation group (n = 25) with meticulous nursing measures. The application effect of the two nursing modes was scientifically evaluated.

Results

No statistical differences in general data were found between the two groups (P > 0.05). After 6 h of intervention, the circulatory function, oxygenation function, and renal function of both groups were better than those before intervention, and central venous pressure (CVP), mean arterial pressure (MAP), blood oxygen (PaO₂), oxygenation index (PaO₂/FiO₂), central venous oxygen saturation (ScvO₂), and urine volume in the observation group were notably higher than those in the control group (P < 0.05). The heart rate (HR), serum creatinine (SCr), and blood lactic acid in the observation group were notably lower than those in the control group (P < 0.05). The 28-day survival rate and quality of life after intervention in the observation group were notably higher than those in the control group, with obvious differences between the two groups (P < 0.05).

Conclusion

Meticulous nursing intervention for patients with posttraumatic sepsis undergoing EGDT can effectively improve the body's functional indexes, which is superior to the routine nursing in controlling the patients' condition, improving the survival rate and quality of life after intervention, and ensuring the clinical treatment effect. Therefore, it is worthy of promotion.

A salivary microbiome-based auxiliary diagnostic model for type 2 diabetes mellitus

OBJECTIVE

Studies have shown that oral microbiota composition is altered in type 2 diabetes mellitus, implying that it is a potential biomarker for diabetes. This study aimed at constructing a noninvasive auxiliary diagnostic model for diabetes based on differences in the salivary microbial community.

DESIGN

Salivary microbiota from 24 treatment-naive type 2 diabetes mellitus patients and 21 healthy populations were detected through 16S rRNA gene sequencing, targeting the V3/V4 region using the MiSeq platform. Salivary microbiome diversity and composition were analyzed so as to establish a diagnostic model for type 2 diabetes.

RESULTS

Salivary microbiome for treatment-naive type 2 diabetes mellitus patients was imbalanced with certain taxa, including Slackia, Mitsuokella, Abiotrophia, and Parascardovia that being significantly dominant, while the abundance of Moraxella was high in healthy controls. Diabetic patients exhibited varying levels of Prevotella nanceiensis and Prevotella melaninogenica which were negatively correlated with glycosylated hemoglobin and fasting blood glucose levels, as well as fasting blood glucose levels, respectively. Based on differences in salivary microbiome composition between diabetic and healthy groups, we developed a diagnostic model that can be used for the auxiliary diagnosis of type 2 diabetes mellitus with an accuracy of 80 %.

CONCLUSIONS

These findings elucidate on the differences in salivary microbiome compositions between type 2 diabetic and non-diabetic populations, and the diagnostic model provides a promising approach for the noninvasive auxiliary diagnosis of diabetes mellitus.

Autotransporters Drive Biofilm Formation and Autoaggregation in the Diderm Firmicute Veillonella parvula

Veillonella parvula is an anaerobic commensal and opportunistic pathogen whose ability to adhere to surfaces or other bacteria and form biofilms is critical for it to inhabit complex human microbial communities such as the gut and oral microbiota. Although the adhesive capacity of V. parvula has been previously described, very little is known about the underlying molecular mechanisms due to a lack of genetically amenable Veillonella strains. In this study, we took advantage of a naturally transformable V. parvula isolate and newly adapted genetic tools to identify surface-exposed adhesins called autotransporters as the main molecular determinants of adhesion in this bacterium. This work therefore provides new insights on an important aspect of the V. parvula lifestyle, opening new possibilities for mechanistic studies of the contribution of biofilm formation to the biology of this major commensal of the oral-digestive tract.

The Negativicutes are a clade of the Firmicutes that have retained the ancestral diderm character and possess an outer membrane. One of the best studied Negativicutes, Veillonella parvula, is an anaerobic commensal and opportunistic pathogen inhabiting complex human microbial communities, including the gut and the dental plaque microbiota. Whereas the adhesion and biofilm capacities of V. parvula are expected to be crucial for its maintenance and development in these environments, studies of V. parvula adhesion have been hindered by the lack of efficient genetic tools to perform functional analyses in this bacterium. Here, we took advantage of a recently described naturally transformable V. parvula isolate, SKV38, and adapted tools developed for the closely related Clostridia spp. to perform random transposon and targeted mutagenesis to identify V. parvula genes involved in biofilm formation. We show that type V secreted autotransporters, typically found in diderm bacteria, are the main determinants of V. parvula autoaggregation and biofilm formation and compete with each other for binding either to cells or to surfaces, with strong consequences for V. parvula biofilm formation capacity. The identified trimeric autotransporters have an original structure compared to classical autotransporters identified in Proteobacteria, with an additional C-terminal domain. We also show that inactivation of the gene coding for a poorly characterized metal-dependent phosphohydrolase HD domain protein conserved in the Firmicutes and their closely related diderm phyla inhibits autotransporter-mediated biofilm formation. This study paves the way for further molecular characterization of V. parvula interactions with other bacteria and the host within complex microbiota environments.

IMPORTANCEVeillonella parvula is an anaerobic commensal and opportunistic pathogen whose ability to adhere to surfaces or other bacteria and form biofilms is critical for it to inhabit complex human microbial communities such as the gut and oral microbiota. Although the adhesive capacity of V. parvula has been previously described, very little is known about the underlying molecular mechanisms due to a lack of genetically amenable Veillonella strains. In this study, we took advantage of a naturally transformable V. parvula isolate and newly adapted genetic tools to identify surface-exposed adhesins called autotransporters as the main molecular determinants of adhesion in this bacterium. This work therefore provides new insights on an important aspect of the V. parvula lifestyle, opening new possibilities for mechanistic studies of the contribution of biofilm formation to the biology of this major commensal of the oral-digestive tract.