Spondylodiscitis and endocarditis caused by S. vestibularis

An Infective Endocarditis Case Report Involving Both Native Aortic and Mitral Valves Due to Streptococcus Vestibularis

Infective endocarditis (IE) is a life-threatening disease, with its mortality rate varying depending on the infectious agent. Streptococci are among the most common causes of infective endocarditis. However, Streptococcus vestibularis has rarely been associated with human infections, typically affecting patients with underlying conditions such as immunosuppressive diseases, valve replacement, rheumatic heart disease, and hemodialysis. We present the case of a 26-year-old man who presented with fever, unanticipated weight loss, and fatigue. Although no typical risk factors for infective endocarditis were identified at admission, transesophageal echocardiography revealed a bicuspid aortic valve with calcification, paravalvular aortic abscess formation, and vegetations on the anterior leaflet of the mitral valve. Blood cultures grew S. vestibularis, which was initially sensitive to benzylpenicillin but developed emergent resistance on the third day of the antibiotic treatment. Subsequently, ceftriaxone therapy was initiated, and blood cultures became sterile on day 10. The patient eventually underwent aortic valve replacement. We report the first known case of native aortic and mitral valve endocarditis caused by S. vestibularis, accompanied by a paravalvular abscess around the native aortic valve, in a patient who had no typical risk factors for infective endocarditis, except for a bicuspid aortic valve.

Human oral lectin ZG16B acts as a cell wall polysaccharide probe to decode host-microbe interactions with oral commensals

The oral microbiome is critical to human health and disease, yet the role that host salivary proteins play in maintaining oral health is unclear. A highly expressed gene in human salivary glands encodes the lectin zymogen granule protein 16 homolog B (ZG16B). Despite the abundance of this protein, its interaction partners in the oral microbiome are unknown. ZG16B possesses a lectin fold, but whether it binds carbohydrates is unclear. We postulated that ZG16B would bind microbial glycans to mediate recognition of oral microbes. To this end, we developed a microbial glycan analysis probe (mGAP) strategy based on conjugating the recombinant protein to fluorescent or biotin reporter functionality. Applying the ZG16B-mGAP to dental plaque isolates revealed that ZG16B predominantly binds to a limited set of oral microbes, including Streptococcus mitis, Gemella haemolysans, and, most prominently, Streptococcus vestibularis. S. vestibularis is a commensal bacterium widely distributed in healthy individuals. ZG16B binds to S. vestibularis through the cell wall polysaccharides attached to the peptidoglycan, indicating that the protein is a lectin. ZG16B slows the growth of S. vestibularis with no cytotoxicity, suggesting that it regulates S. vestibularis abundance. The mGAP probes also revealed that ZG16B interacts with the salivary mucin MUC7. Analysis of S. vestibularis and MUC7 with ZG16B using super-resolution microscopy supports ternary complex formation that can promote microbe clustering. Together, our data suggest that ZG16B influences the compositional balance of the oral microbiome by capturing commensal microbes and regulating their growth using a mucin-assisted clearance mechanism.

Glycan Biosynthesis Ability of Gut Microbiota Increased in Primary Hypertension Patients Taking Antihypertension Medications and Potentially Promoted by Macrophage-Adenosine Monophosphate-Activated Protein Kinase

Increasing evidences suggest that the gut microbiota have their contributions to the hypertension, but the metagenomic characteristics and potential regulating mechanisms in primary hypertension patients taking antihypertension drugs are not clear yet. We carried out a metagenomic analysis in 30 primary hypertension patients taking antihypertension medications and eight healthy adults without any medication. We found that bacterial strains from species, such as Bacteroides fragilis, Bacteroides vulgatus, Escherichia coli, Klebsiella pneumoniae, and Streptococcus vestibularis, were highly increased in patients; and these strains were reported to generate glycan, short-chain fatty acid (SCFA) and trimethylamine (TMA) or be opportunistic pathogens. Meanwhile, Dorea longicatena, Eubacterium hallii, Clostridium leptum, Faecalibacterium prausnitzii, and some other strains were greatly decreased in the patient group. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found that ortholog groups and pathways related to glycan biosynthesis and multidrug resistance were significantly increased in the patient group, and some of the hub genes related to N-glycan biosynthesis were increased in the patient group, while those related to TMA precursor metabolism and amino acid metabolism both increased and decreased in the patient group. Metabolites tested by untargeted liquid chromatography–mass spectrometry (LC-MS) proved the decrease of acetic acid, choline, betaine, and several amino acids in patients’ fecal samples. Moreover, meta-analysis of recent studies found that almost all patients were taking at least one kind of drugs that were reported to regulate adenosine monophosphate-activated protein kinase (AMPK) pathway, so we further investigated if AMPK regulated the metagenomic changes by using angiotensin II-induced mouse hypertensive model on wild-type and macrophage-specific AMPK-knockout mice. We found that the changes in E. coli and Dorea and glycan biosynthesis-related orthologs and pathways were similar in our cohort and hypertensive wild-type mice but reversed after AMPK knockout. These results suggest that the gut microbiota-derived glycan, SCFA, TMA, and some other metabolites change in medication-taking primary hypertension patients and that medications might promote gut microbiota glycan biosynthesis through activating macrophage-AMPK.

Problems with identifying and distinguishing salivary streptococci: a multi-instrumental approach

Aim: The purpose of this study was to create an alternative protocol for the DNA-based identification of salivary microbiota focused on the distinguishing of Streptococcus species. Materials & methods: Salivary bacteria were identified using 16S rDNA sequencing and proteins and lipids profiling using MALDI-TOF/MS as well as FTIR analysis. Results: Most of the isolates belonged to streptococci - mostly the salivarious group indistinguishable by the molecular technique. In turn, MALDI analysis allowed for their fast and reliable classification. Although FTIR spectroscopy demonstrated the correct species classification, the spectra interpretation was time consuming and complicated. Conclusion: MALDI-TOF/MS demonstrated the biggest effectiveness in the identification and discrimination between the salivary streptococci, which could be easily incorporated in the workflow of routine microbiological laboratories.

Asymptomatic pyogenic liver abscesses secondary to Fusobacterium nucleatum and Streptococcus vestibularis in an immunocompetent patient

A 66-year-old male patient presented with symptoms and signs of L4/5 radiculopathy. He was found to be anaemic with elevated inflammatory markers and deranged hepatic enzymes. Imaging revealed lumbar canal stenosis and the presence of pyogenic liver abscesses from which Fusobacterium nucleatum and Streptococcus vestibularis were isolated. The hepatic abscesses were attributed to asymptomatic diverticular perforation. Multiple coexisting incidental infections were discovered, including oesophageal candidiasis, Helicobacter pylori, stool cultures positive for Strongyloides stercoralis, and sputum cultures positive for Enterobacter cloacae, Escherichia coli and Mycobacterium avium Extensive investigations for possible underlying immunosuppression were negative.