Gemella sanguinis endocarditis with c-ANCA/anti-PR-3-associated immune complex necrotizing glomerulonephritis with a 'full-house' pattern on immunofluorescence microscopy

Gemella sanguinis: A Rare Cause of Endocarditis in a Bicuspid Aortic Valve

Here, we present a case of infective endocarditis (IE) caused by Gemella sanguinis, a pathogen that rarely causes human infection. The patient in this case was an otherwise healthy 50-year-old man who presented with gradually worsening shortness of breath, weight loss, fatigue, chills, and leg swelling for six weeks. He had no prior history of cardiac disease and had never used intravenous drugs, but he had undergone extensive dental work following a military-associated injury. A workup for IE was done, and echocardiography revealed a bicuspid aortic valve (BAV) with vegetations causing moderate to severe aortic regurgitation. Blood cultures, which initially showed only gram-positive cocci, later identified Gemella sanguinis. He subsequently recovered after receiving treatment with antibiotics and undergoing an aortic valve replacement. The patient's BAV and significant dental history acted as risk factors for this condition, and although his symptoms were nonspecific and he did not exhibit other classic risk factors for IE, his case represents the importance of keeping high clinical suspicion to allow for prompt initiation of appropriate treatment. More research on Gemella is needed, as these species are difficult to identify and therefore may be a more significant cause of infection than is currently known.

Antineutrophil cytoplasmic antibodies in infective endocarditis: a case report and systematic review of the literature

Infective endocarditis (IE) may be misdiagnosed as ANCA-associated vasculitis (AAV), especially when antineutrophil cytoplasmic antibodies (ANCA) are detected. Distinguishing IE from AAV is crucial to guide therapy. However, little is known about ANCA positivity in IE patients. We present a case report and systematic review of the literature on patients with ANCA-positive IE, aiming to provide a comprehensive overview of this entity and to aid clinicians in their decisions when encountering a similar case. A systematic review of papers on original cases of ANCA-positive IE without a previous diagnosis of AAV was conducted on PubMed in accordance with PRISMA-IPD guidelines. A predefined set of clinical, laboratory, and kidney biopsy findings was extracted for each patient and presented as a narrative and quantitative synthesis. A total of 74 reports describing 181 patients with ANCA-positive IE were included (a total of 182 cases including our own case). ANCA positivity was found in 18-43% of patients with IE. Patients usually presented with subacute IE (73%) and had positive cytoplasmic ANCA-staining or anti-proteinase-3 antibodies (79%). Kidney function was impaired in 72%; kidney biopsy findings were suggestive of immune complexes in 59%, while showing pauci-immune glomerulonephritis in 37%. All were treated with antibiotics; 39% of patients also received immunosuppressants. During follow-up, 69% of patients became ANCA-negative and no diagnosis of systemic vasculitis was reported. This study reviewed the largest series of patients with ANCA-positive IE thus far and shows the overlap in clinical manifestations between IE and AAV. We therefore emphasize that clinicians should be alert to the possibility of an underlying infection when treating a patient with suspected AAV, even when reassured by ANCA positivity. Key Points • This systematic review describes - to our knowledge - the largest series of patients with ANCA-positive infective endocarditis (IE) thus far (N=182), and shows a high degree of overlap in clinical manifestations between IE and ANCA-associated vasculitis (AAV). • ANCA positivity was found in 18-43% of patients with infective endocarditis. Of patients with ANCA-positive IE, the majority (79%) showed cytoplasmic ANCA-staining or anti-PR3-antibodies. We emphasize that clinicians should be alert to the possibility of an underlying infection when treating a patient with suspected AAV, even when reassured by ANCA positivity. • In patients with IE and ANCA-associated symptoms such as acute kidney injury, an important clinical challenge is the initiation of immunosuppressive therapy. All patients with data in this series received antibiotics; 39% also received immunosuppressive therapy. In many of these patients, ANCA-associated symptoms resolved or stabilized after infection was treated. ANCA titers became negative in 69% , and a diagnosis of AAV was made in none of the cases. We therefore recommend that (empiric) antibiotic treatment remains the therapeutic cornerstone for ANCA-positive IE patients, while a watchful wait-and-see approach with respect to immunosuppression is advised.

Bartonella endocarditis and diffuse crescentic proliferative glomerulonephritis with a full-house pattern of immune complex deposition

Background

Bartonella endocarditis is often a diagnostic challenge due to its variable clinical manifestations, especially when it is first presented with involvement of organs other than skin and lymph nodes, such as the kidney.

Case presentation

This was a 13-year-old girl presenting with fever, chest and abdominal pain, acute kidney injury, nephrotic-range proteinuria and low complement levels. Her kidney biopsy showed diffuse crescentic proliferative glomerulonephritis with a full-house pattern of immune complex deposition shown by immunofluorescence, which was initially considered consistent with systemic lupus erythematous-associated glomerulonephritis (lupus nephritis). After extensive workup, Bartonella endocarditis was diagnosed. Antibiotic treatment and valvular replacement surgery were undertaken with subsequent return of kidney function to normal range.

Conclusion

This case demonstrates the importance of considering the full clinical picture when interpreting clinical, laboratory and biopsy findings, because the treatment strategy for infective endocarditis versus lupus nephritis is drastically different.

Risk Factors and Patient Profile of Infective Endocarditis due to Gemella spp

BACKGROUND

The diagnosis of infective endocarditis is difficult, especially when it involves atypical organisms. Therefore, our study identified risk factors of infective endocarditis caused by rare pathogen, Gemella spp.

METHODS

A systematic review was conducted to investigate characteristics of endocarditis patients infected with Gemella spp. using the search term "Gemella" and "endocarditis." Case reports were gathered by searching Medline/Pubmed, Google Scholar, CINAHL, Cochrane CENTRAL, and Web of Science databases. 83 articles were selected for review.

RESULTS

Five species of Gemella were identified. Typical patients were males between 31 and 45 years of age. On admission, patients had fever, tachycardia, and normal blood pressure. Common clinical manifestation other than fever included fatigue and weakness, chills and sweating, and nausea, vomiting, diarrhea, and weight changes. One in four reported a history of congenital heart disease, and a recent oral cavity infection. Laboratory tests reveal anemia, leukocytosis, and elevated erythrocyte sedimentation in all age groups, elevated C-reactive protein is observed among adult and geriatric populations only. Mitral and aortic valves were most commonly infected by Gemella spp.. The most common Gemella spp.-susceptible antibiotics were penicillin, vancomycin, cephalosporin, macrolide, and aminoglycosides. However, antibiotic resistance was observed against penicillin, aminoglycoside, and fluoroquinolone. Antibiotic course of at least six weeks resulted in superior clinical improvements than durations under six weeks. Finally, one in two patients underwent valve replacement or repair, with common complications affecting the cardiovascular, neurological, and renal systems. Finally, death occurred in 1 in 8 patients, half of which occurred post-surgical procedure, and the majority occurring equal to or greater than 1 week from admission.

CONCLUSION

Our systematic review highlights the importance of considering rare pathogens, particularly in the presence of predisposing risk factors.

Antineutrophil cytoplasmic antibody-positive infective endocarditis complicated by acute kidney injury: a case report and literature review

Patients with infective endocarditis (IE) may present with multisystem disturbances resembling autoimmune diseases, such as antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The kidneys are susceptible to damage in IE and AAV, which is a source of diagnostic ambiguity. Therefore, distinguishing infection from an inflammatory process is pivotal for guiding appropriate therapy. We report a 22-year-old man with IE characterized by ANCA positivity and complicated by acute kidney injury. A renal biopsy showed crescentic nephritis with tubulointerstitial lesions. However, transthoracic echocardiography and blood culture provided evidence of IE, and AAV was ruled out. Surgical intervention and antibiotic treatments were successful. We summarized previously reported cases of ANCA-positive IE that had renal biopsy data. We found that ANCA-positive IE can involve multiple organs. The representative renal pathology was crescentic nephritis, focal segmental glomerulonephritis, mesangial cell proliferation, tubular injury, and interstitial oedema. Immunofluorescence showed predominate C3 deposits. Electron microscopy showed electron-dense deposits in the subendothelial or mesangial areas. Eight patients received immunosuppressive therapy with excellent results. Repeated testing for bacterial pathogens and multiple renal biopsies may be useful for diagnosing ANCA-positive IE. With ANCA-positive IE, immunosuppressive therapy along with antibiotic treatments may be beneficial for recovery of renal function.

A rare case of isolated mitral valve endocarditis by Gemella sanguinis: Case report and review of the literature

•

Gemella sanguinis is a very rare cause of infective endocarditis.

•

Only 12 cases previously reported in the literature, only two of which involved exclusively the mitral valve.

•

Usually associated with preexisting cardiac condition or oral infection/instrumentation.

•

Valve replacement along with prolonged antibiotic course resulted in successful outcomes in the majority of cases.

Introduction

Gemella sanguinis is an extremely rare cause of infectious endocarditis, with only 12 cases previously reported in the literature. Here we report the third known case of isolated mitral valve endocarditis secondary to G. sanguinis.

Presentation of case

A 53-year-old man with mitral valve prolapse and history of recent dental instrumentation presented with malaise, thigh and finger pain and new pansystolic murmur. He was diagnosed with severe mitral insufficiency due to infectious endocarditis secondary to G. sanguinis. He underwent mitral valve replacement and was treated with a long course of antibiotics.

Discussion

G. sanguinis is a rare cause of infectious endocarditis with very few reported cases in the literature. In the majority of reported cases, a strategy of valve replacement along with prolonged antibiotic course results in good outcome for the patient.

Proteinase 3-antineutrophil cytoplasmic antibody-positive necrotizing crescentic glomerulonephritis complicated by infectious endocarditis: a case report

Background

Proteinase 3-antineutrophil cytoplasmic antibody has been reported to be positive in 5–10% of cases of renal injury complicated by infective endocarditis; however, histological findings have rarely been reported for these cases.

Case presentation

A 71-year-old Japanese man with a history of aortic valve replacement developed rapidly progressive renal dysfunction with gross hematuria and proteinuria. Blood analysis showed a high proteinase 3-antineutrophil cytoplasmic antibody (163 IU/ml) titer. Streptococcus species was detected from two separate blood culture bottles. Transesophageal echocardiography detected mitral valve vegetation. Histological evaluation of renal biopsy specimens showed necrosis and cellular crescents in glomeruli without immune complex deposition. The patient met the modified Duke criteria for definitive infective endocarditis. On the basis of these findings, the patient was diagnosed with proteinase 3-antineutrophil cytoplasmic antibody-positive necrotizing crescentic glomerulonephritis complicated by Streptococcus infective endocarditis. His renal disease improved, and his proteinase 3-antineutrophil cytoplasmic antibody titer normalized with antibiotic monotherapy.

Conclusion

Few case reports have described histological findings of proteinase 3-antineutrophil cytoplasmic antibody-positive renal injury complicated with infective endocarditis. We believe that an accumulation of histological findings and treatments is mandatory for establishment of optimal management for proteinase 3-antineutrophil cytoplasmic antibody-positive renal injury complicated with infective endocarditis.

Functional Multigenomic Screening of Human-Associated Bacteria for NF-κB-Inducing Bioactive Effectors

The effect of the microbiota on its human host is driven, at least in part, by small-molecule and protein effectors it produces. Here, we report on the use of functional multigenomic screening to identify microbiota-encoded effectors. In this study, genomic DNA from 116 human-associated bacteria was cloned en masse, and the resulting multigenomic library was screened using a nuclear factor-κB reporter (NF-κB) assay. Functional multigenomics builds on the concept of functional metagenomics but takes advantage of increasing advances in cultivating and sequencing human-associated bacteria. Effector genes found to confer NF-κB-inducing activity to Escherichia coli encode proteins in four general categories: cell wall hydrolases, membrane transporters, lipopolysaccharide biosynthetic enzymes, and proteins of unknown function. The compact nature of multigenomic libraries, which results from the ability to normalize input DNA ratios, should simplify screening of libraries using diverse heterologous hosts and reporter assays, increasing the rate of discovery of novel effector genes.IMPORTANCE Human-associated bacteria are thought to encode bioactive small molecules and proteins that play an intimate role in human health and disease. Here, we report on the creation and functional screening of a multigenomic library constructed using genomic DNA from 116 bacteria found at diverse sites across the human body. Individual clones were screened for genes capable of conferring NF-κB-inducing activity to Escherichia coli NF-κB is a useful reporter for a range of cellular processes related to immunity, pathogenesis, and inflammation. Compared to the screening of metagenomic libraries, the ability to normalize input DNA ratios when constructing a multigenomic library should facilitate the more efficient examination of commensal bacteria for diverse bioactivities. Multigenomic screening takes advantage of the growing available resources in culturing and sequencing the human microbiota and generates starting points for more in-depth studies on the mechanisms by which commensal bacteria interact with their human host.

Bicuspid aortic valve endocarditis caused by Gemella sanguinis: Case report and literature review

Gemella species are catalase-negative, facultative anaerobic, Gram-positive cocci, which are part of the human oral microbiome and may occasionally cause systemic infections. Infective endocarditis (IE) has been reported as the most common infection caused by Gemella species. We report the first case of IE due to Gemella sanguinis in Greece, in a patient with bicuspid aortic valve and review the available literature. The patient was successfully treated with antibiotics and aortic valve replacement.

A Case Report of Successful Conservative Treatment for Infective Endocarditis Caused by Gemella sanguinis

Infective endocarditis is defined as an infection of a native or prosthetic heart valve, the endocardial surface of the heart, or an indwelling cardiac device. Among the miscellaneous emerging opportunistic bacteria that can cause infective endocarditis is Gemella sanguinis that has been reported as a cause of infective endocarditis in nine cases in the past. All of the survivors received antimicrobial therapy and underwent prosthetic valve replacement surgery while, in general, a proportion of 40-50% of the patients with infective endocarditis underwent valve surgery. Our case illustrates that valve surgery, in combination with the administration of antibiotics, is not the only therapeutic option for infective endocarditis due to Gemella sanguinis and that a conservative management with prolonged administration of parenteral antibiotics under close supervision of the patient can be an option.

Two Cases of Proteinase 3-Anti-Neutrophil Cytoplasmic Antibody (PR3-ANCA)-related Nephritis in Infectious Endocarditis

We herein report two cases of proteinase 3-anti-neutrophil cytoplasmic antibody (PR3-ANCA)-related nephritis in infectious endocarditis. In both cases, the patients were middle-aged men with proteinuria and hematuria, hypoalbuminemia, decreased kidney function, anemia, elevated C-reactive protein (CRP) levels, and PR3-ANCA positivity. Each had bacteremia, due to Enterococcus faecium in one and Streptococcus bovis in the other. One patient received aortic valve replacement therapy for aortic regurgitation with vegetation, and the other underwent tricuspid valve replacement therapy and closure of a ventricular septic defect to treat tricuspid regurgitation with vegetation. These patients' urinary abnormalities and PR3-ANCA titers improved at 6 months after surgery following antibiotic treatment without steroid therapy.