StaphylococcusInfection-Associated Glomerulonephritis Mimicking IgA Nephropathy

Infection-Associated Glomerulonephritis

The nephritic syndrome has been associated with a wide variety of infections, spanning many organisms and myriad clinical presentations. Infection-associated glomerulonephritis is challenging to diagnose given the many confounding factors linking kidney injury to infection; however, urine microscopy can assist in identifying abnormal cellular elements suggestive of glomerulonephritis. Kidney biopsy remains the gold standard for diagnosing the underlying pathologic lesion. Treatment of infection-associated glomerulonephritis centers around aggressive and complete treatment of the underlying infectious driver. It is often hard to know exactly when immunosuppression may be required in addition to treating the infection.

A cluster of type I interferon-regulated genes associates with disease activity and prognosis in patients with IgA nephropathy

The exact pathogenesis of IgA nephropathy (IgAN) is complex and so far, not well defined. Since it has been shown that microbial infections could induce high levels of type I interferon (IFN-I) and there is an evident link between mucosal infection and gross hematuria in IgAN, we hypothesized that IFN-I may play a role in the pathogenic process. In this study, we investigated the type I interferon status in IgAN based on the expression of 17 IFN-regulated genes (IRGs) in whole blood from 59 IgAN patients in a cross-sectional study, of which 34 patients followed longitudinally. Analysis of the IFN-score showed that there was a significant elevated IFN-score in the IgAN patients compared with healthy controls (n = 28, p = 9.80 × 10-3), and we observed an elevated IFN-score in the group with less tubular atrophy/interstitial fibrosis (p = 1.07 × 10-2) and with a lower proportion of mesangial hypercellularity (p = 1.23 × 10-2). In the longitudinal analysis, Cox regression analysis revealed that a higher IFN level was associated with a better renal outcome in IgAN after adjustments for gender and age (hazard ratio, 0.90; 95 % confidence interval, 0.81 to 0.97; p = 4.20 × 10-2). In conclusion, our finding suggested that IFN score may represent a novel type of biomarker in IgAN, which requires further exploration on its mechanism and therapeutic targeting.

Infection-Related Glomerulonephritis in Children and Adults

Infection-related glomerulonephritis is an immunologically mediated glomerular injury after an infection. Glomerulonephritis may occur with the infection or after a variable latent period. Poststreptococcal glomerulonephritis (PSGN) is the prototype of infection-related glomerulonephritis. The streptococcal antigens, nephritis-associated plasmin-like receptor and streptococcal exotoxin B, have emerged as major players in the pathogenesis of PSGN. Although PSGN is the most common infection-related glomerulonephritis in children, in adults, glomerulonephritis is secondary to bacteria such as staphylococci, viruses such as hepatitis C, and human immunodeficiency virus, and, rarely, parasitic infections. Supportive therapy is the mainstay of treatment in most infection-related glomerulonephritis. Treatment of the underlying infection with specific antibiotics and antiviral medications is indicated in some infections. Parasitic infections, although rare, may be associated with significant morbidity. Poststreptococcal glomerulonephritis is a self-limiting condition with a good prognosis. However, bacterial, viral, and parasitic infections may be associated with significant morbidity and long-term consequences. Epidemiologic studies are required to assess the global burden of infection-related glomerulonephritis. A better understanding of the pathogenesis of infection-related glomerulonephritis may unravel more treatment options and preventive strategies.

IgA nephropathy in adults with epidermolysis bullosa

Epidermolysis bullosa (EB) is a devastating genetic condition caused by mutations in genes that give rise to aberrant proteins. There are 16 different such proteins implicated in EB that are important in maintaining the integrity of the dermoepidermal junction. It is classified into four major subtypes: (i) EB simplex; (ii) junctional EB (JEB); (iii) dystrophic EB (DEB); and (iv) Kindler EB. Renal disease is a recognized complication of EB and the aetiology is complex. We describe our experience of managing five patients with EB and IgA nephropathy. We recommend that patients with recessive DEB and JEB routinely have the following monitored: renal function, urinary albumin/creatinine ratio, urine analysis, serum albumin levels and immunoglobulins; specifically serum IgA. Management of IgA nephropathy in the context of EB should be tailored to the individual and be carried out within a specialist multidisciplinary team. Our case series provides important insights into the treatment of IgA nephropathy in patients with EB and will help inform treatment in this rare genetic disease. Case series and reports like ours are key in gaining real-life data to quantify the actual risk of morbidity and mortality from each of the treatment modalities discussed.

The Diagnostic Conundrum of Glomerular Crescents With IgA Deposits

Introduction

Glomerulonephritis (GN) with crescents and IgA deposits in kidney biopsy poses a frequent diagnostic and therapeutic dilemma because of multiple possibilities.

Methods

Native kidney biopsies showing glomerular IgA deposition and crescents (excluding lupus nephritis) were identified from our biopsy archives between 2010 and 2021. Detailed clinicopathologic features were assessed. One-year clinical follow-up on a subset of cases was obtained.

Results

A total of 285 cases were identified, and these clustered into IgA nephropathy (IgAN, n = 108), Staphylococcus or other infection-associated GN/infection-related GN (SAGN/IRGN, n = 43), and antineutrophil cytoplasmic antibody-associated GN (ANCA-GN, n = 26) based on a constellation of clinicopathologic features, but 101 cases (group X) could not be definitively differentiated. The reasons have been elucidated, most important being atypical combination of clinicopathologic features and lack of definitive evidence of active infection. Follow-up (on 72/101 cases) revealed that clinicians' working diagnosis was IgAN in 43%, SAGN/IRGN in 22%, ANCA-GN in 28%, and others in 7% of the cases, but treatment approach varied from supportive or antibiotics to immunosuppression in each subgroup. Comparing these cases as "received immunosuppression" versus "non-immunosuppression," only 2 features differed, namely C3-dominant staining, and possibility of recent infection (both higher in the no-immunosuppression group) (P < 0.05). Renal loss was higher in the non-immunosuppression subgroup, but not statistically significant (P = 0.11).

Conclusion

Diagnostic overlap may remain unresolved in a substantial number of kidney biopsies with glomerular crescents and IgA deposits. A case-by-case approach, appropriate antibiotics if infection is ongoing, and consideration for cautious immunosuppressive treatment for progressive renal dysfunction may be needed for best chance of renal recovery.

An Unusual Case of Seronegative Cryoglobulinemic Glomerulonephritis with Dominant Organized IgA Deposits Associated with Staphylococcal Infection: Casual or Causal Relationship?

Introduction

Cryoglobulinemia refers to the presence of cryoglobulins (CGs) in the serum, encompassing a group of diseases caused by the type of circulating GC. Cryoglobulinemic glomerulonephritis (CryoGN) is the principal manifestation of renal involvement. The diagnosis may be challenging because the hallmark of cryoglobulinemia is the detection of CG in the serum. However, cases of CryoGN without serological evidence of CGs are not uncommon in clinical practice, often diagnosed by anatomopathological findings in the renal biopsy.

Case Presentation

We report the case of an 86-year-old male who developed renal impairment, nephritic syndrome, and nephrotic-range proteinuria, without serological evidence of CGs, associated with staphylococcal bacteremia without apparent focus. Renal biopsy and pathological examination showed a membranoproliferative glomerulonephritis pattern with CD61-negative pseudothrombi. Immunofluorescence microscopy showed atypical IgA-dominant deposits. Electron microscopy revealed amorphous subendothelial and mesangial deposits and organized electrodense deposits within capillary loops (pseudothrombi) with microtubular substructure measuring 20-40 nm in thickness. These findings were consistent with seronegative CryoGN and microtubular organized atypical IgA-dominant deposits.

Discussion

In this report, we discuss the clinical, analytical, and histopathological findings of a rare case of CryoGN without serological evidence of CGs. Regarding the etiology that triggered the glomerular disease in our patient, we conducted an exhaustive study in order to determine the underlying cause of CryoGN. At the time of biopsy, the patient had an active staphylococcal bacteremia. There are reports that postulate that staphylococcal antigens drive activation of immune system and in consequence, could cause this rare form of IgA-dominant glomerulonephritis with cryoglobulinemic features. After ruling out other causes of cryoglobulinemia, we discuss a plausible causal relationship of the staphylococcal infection in the pathogenesis of CryoGN in our patient.

Triple hit to the kidney-dual pathological crescentic glomerulonephritis and diffuse proliferative immune complex-mediated glomerulonephritis: A case report

BACKGROUND

Anti-glomerular basement membrane (GBM) disease is a rare rapidly progressive glomerulonephritis, frequently associated with alveolar hemorrhage in the lungs and involving the kidney by crescentic glomerulonephritis. It has been described in association with other glomerulonephritides [such as anti-neutrophilic antibody (ANCA)-glomerulonephritis, membranous nephropathy, and immunoglobulin (Ig)A nephropathy].

CASE SUMMARY

Herein we present an unusual case of concurrent anti-GBM disease, ANCA-associated crescentic glomerulonephritis and diffuse proliferative immune complex mediated glomerulonephritis with predominant staining for IgA and C3 by immunofluorescence. The patient is a 46-year-old Caucasian male who presented to the emergency department with acute onset of flank pain and was found to have high serum creatinine levels of 15 mg/dL, proteinuria, and hematuria. He rapidly deteriorated and became anuric. He was found to have high anti-GBM antibodies titers (151 units) and high anti-neutrophil cytoplasmic-ANCA. Despite prompt and early treatment, the patient’s condition worsened, and he succumbed to his illness.

CONCLUSION

Our case emphasizes the importance of a renal biopsy in anti-GBM disease, even in the presence of positive serum anti-GBM antibodies, to identify other potential causes of rapidly progressive glomerulonephritis. The challenge in treating such cases lies in the different therapy modalities.

Staphylococcus aureus skin colonization promotes SLE-like autoimmune inflammation via neutrophil activation and the IL-23/IL-17 axis

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by inflammation of various organs such as skin, kidneys, bones, and brain and the presence of autoantibodies. Although the cause of SLE is not completely understood, environmental factors, genetic susceptibility, hormone factors, and environmental factors are thought to play essential roles in the pathogenesis of SLE. Among environmental factors, the microbiota are linked to the development of different autoimmune diseases. The microbiota in the nasal cavity and gut are involved in SLE development, but the influence of skin microbiota is still unclear. Here, we demonstrated that epithelial cell-specific IκBζ-deficient (Nfkbiz^ΔK5) mice showed spontaneous skin inflammation with increased abundance of Staphylococcus aureus on the skin. When S. aureus was epicutaneously applied on Nfkbiz^ΔK5 mice, Nfkbiz^ΔK5 mice developed SLE-associated autoantibodies, anti-dsDNA antibodies, anti-Sm antibodies, and glomerulonephritis with IgG deposition. Epicutaneous S. aureus application significantly increased staphylococcal colonization on the skin of Nfkbiz^ΔK5 mice with reduced expression of several antimicrobial peptides in the skin. This staphylococcal skin colonization promoted caspase-mediated keratinocyte apoptosis and neutrophil activation, inducing the interleukin-23 (IL-23)/IL-17 immune response by activating dendritic cells and T cells. Furthermore, the subcutaneous administration of anti-IL-23p19 and anti-IL-17A antibodies alleviated the systemic autoimmune response. Together, these findings underscore epithelial-immune cross-talk disturbances caused by skin dysbiosis as an essential mediator inducing autoimmune diseases.

A rare case of Immunoglobulin A dominant post-infectious glomerulonephritis (IgA PIGN) in a young patient

Background

Immunoglobulin A dominant postinfectious glomerulonephritis (IgA PIGN) is a unique medical entity that is rare in the paediatric population. It usually presents with severe renal failure, heavy proteinuria, hypertension, and hypocomplementemia and frequently has an unfavourable prognosis. IgA PIGN generally occurs in association with staphylococcal infections and diabetes mellitus in adult patients. Other pathogens include Escherichia coli and Streptococcus sp. Immunofluorescence studies of kidney biopsy samples show IgA as dominant or codominant antibody.

Case presentation

We encountered a 3-year-old girl with IgA PIGN presenting with acute renal failure, oedema, hypertension, and heavy proteinuria of 7955 mg/g creatinine. Renal biopsy specimens showed diffuse glomerular endocapillary hypercellularity with prominent neutrophil and monocyte infiltration on light microscopy. Strong deposits of IgA and C₃ were observed along the glomerular basement membranes and the mesangium by immunofluorescence microscopy, and electron microscopy revealed the presence of subepithelial humps.

The patient was managed with steroid (and probatory antibiotic) therapy and is now undergoing follow-up, with a significant improvement 6 months after the initial presentation (glomerular filtration rate (GFR) and cystatin C clearance rate of 165 ml/min/1.73m² and 106 ml/min/1.73m², respectively). No signs of bacterial infection were detectable.

Conclusion

This variant of IgA PIGN must be distinguished from other clinical entities, especially IgA nephropathy (mesangial IgA deposits) and postinfectious glomerulonephritis (C3, IgG and occasional IgM capillary loop deposits with or without mesangial distribution), since patients with IgA PIGN may require steroid treatment in addition to antibiotic therapy. Differential diagnosis should also include C₃ glomerulopathy.

IgA PIGN is a recently identified disease entity that generally manifests in adult patients with both IgA and C3 mesangial and glomerular capillary wall deposits. We present a biopsy-proven case of IgA PIGN that manifested in a patient at an exceptionally young age and that has had a good clinical outcome. To the best of our knowledge, this is the youngest IgA PIGN patient reported thus far.

Staphylococcus aureus Infection-Related Glomerulonephritis with Dominant IgA Deposition

Since 1995, when we reported the case of a patient with glomerulonephritis with IgA deposition that occurred after a methicillin-resistant Staphylococcus aureus (MRSA) infection, many reports of MRSA infection-associated glomerulonephritis have accumulated. This disease is being systematized as Staphylococcus infection-associated glomerulonephritis (SAGN) in light of the apparent cause of infection, and as immunoglobulin A-dominant deposition infection-related glomerulonephritis (IgA-IRGN) in light of its histopathology. This glomerulonephritis usually presents as rapidly progressive glomerulonephritis or acute kidney injury with various degrees of proteinuria and microscopic hematuria along with an ongoing infection. Its renal pathology has shown several types of mesangial and/or endocapillary proliferative glomerulonephritis with various degrees of crescent formation and tubulointerstitial nephritis. IgA, IgG, and C₃ staining in the mesangium and along the glomerular capillary walls have been observed on immunofluorescence examinations. A marked activation of T cells, an increase in specific variable regions of the T-cell receptor β-chain-positive cells, hypercytokinemia, and increased polyclonal immune complexes have also been observed in this glomerulonephritis. In the development of this disease, staphylococcal enterotoxin may be involved as a superantigen, but further investigations are needed to clarify the mechanisms underlying this disease. Here, we review 336 cases of IgA-IRGN and 218 cases of SAGN.

Acute Post-Streptococcal Glomerulonephritis In Children: A Comprehensive Review

BACKGROUND

Acute post-streptococcal glomerulonephritis (APSGN) is an immune-complex (ICs) mediated glomerular disease triggered by group A β-hemolytic streptococcus (GAS) or Streptococcus pyogenes infections. APSGN represents a major cause of acquired kidney injury in children.

METHODS

This non-systematic review summarizes recent evidence on APSGN. We discuss the epidemiology, pathogenesis, clinical and laboratory findings, histopathology, treatment and prognosis of the disease.

RESULTS

The median APSGN incidence in children in developing countries is estimated at 24.3/100,000 per year, compared with 6.2/100,000 per year in developed countries. Nephritis-associated plasmin receptor, identified as glyceraldehyde-3-phosphate dehydrogenase, and the cationic cysteine proteinase streptococcal pyrogenic exotoxin B are thought to be two leading streptococcal antigens involved in the pathogenesis of APSGN, which activate the complement system, mainly via the alternative but also the lectin pathway. This process is critical for the generation of inflammation by the ICs deposited in the glomerulus. The classic phenotype is an acute diffuse proliferative glomerulonephritis leading to features of the nephritic syndrome including hematuria, oliguria, hypertension and edema. The histopathology shows that the glomeruli are diffused affected, mostly presenting enlarged glomerular tuffs due to hypercellularity. Proliferative endothelial and mesangial cells and inflammation are also observed. APSGN frequently has spontaneous recovery. There is no specific therapy, but its morbidity and mortality are drastically reduced by the prevention and/or treatment of complications.

CONCLUSION

Despite recent advances, the pathogenesis of APSGN is not fully understood. There is no specific treatment for APSGN. The prognosis is generally good. However some cases may evolve to chronic kidney disease.

Variable-heavy (VH) families influencing IgA1&2 engagement to the antigen, FcαRI and superantigen proteins G, A, and L

Interest in IgA as an alternative antibody format has increased over the years with much remaining to be investigated in relation to interactions with immune cells. Considering the recent whole antibody investigations showing significant distal effects between the variable (V) and constant (C)- regions that can be mitigated by the hinge regions of both human IgA subtypes A1 and A2, we performed an in-depth mechanistic investigation using a panel of 28 IgA1s and A2s of both Trastuzumab and Pertuzumab models. FcαRI binding were found to be mitigated by the differing glycosylation patterns in IgA1 and 2 with contributions from the CDRs. On their interactions with antigen-Her2 and superantigens PpL, SpG and SpA, PpL was found to sterically hinder Her2 antigen binding with unexpected findings of IgAs binding SpG at the CH2-3 region alongside SpA interacting with IgAs at the CH1. Although the VH3 framework (FWR) is commonly used in CDR grafting, we found the VH1 framework (FWR) to be a possible alternative when grafting IgA1 and 2 owing to its stronger binding to antigen Her2 and weaker interactions to superantigen Protein L and A. These findings lay the foundation to understanding the interactions between IgAs and microbial superantigens, and also guide the engineering of IgAs for future antibody applications and targeting of superantigen-producing microbes.

Is There a Role for Gut Microbiome Dysbiosis in IgA Nephropathy?

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis and one of the leading causes of renal failure worldwide. The pathophysiology of IgAN involves nephrotoxic IgA1-immune complexes. These complexes are formed by galactose-deficient (Gd) IgA1 with autoantibodies against the hinge region of Gd-IgA1 as well as soluble CD89, an immune complex amplifier with an affinity for mesangial cells. These multiple molecular interactions result in the induction of the mesangial IgA receptor, CD71, injuring the kidney and causing disease. This review features recent immunological and microbiome studies that bring new microbiota-dependent mechanisms developing the disease based on data from IgAN patients and a humanized mouse model of IgAN. Dysbiosis of the microbiota in IgAN patients is also discussed in detail. Highlights of this review underscore that nephrotoxic IgA1 in the humanized mice originates from mucosal surfaces. Fecal microbiota transplantation (FMT) experiments in mice using stools from patients reveal a possible microbiota dysbiosis in IgAN with the capacity to induce progression of the disease whereas FMT from healthy hosts has beneficial effects in mice. The continual growth of knowledge in IgAN patients and models can lead to the development of new therapeutic strategies targeting the microbiota to treat this disease.

A Case of Immunoglobulin A (IgA)-Dominant Infection-Related Glomerulonephritis Treated With Plasmapheresis

Immunoglobulin A (IgA)-dominant infection-related glomerulonephritis (IRGN) is mostly associated with Staphylococcal or other bacterial infections like Streptococcus and Gram-negative bacilli. Antibiotics are the cornerstone of treatment in these cases. When the bacterial infection can’t be recognized or IRGN persists despite treating the underlying infection, controlling the kidney injury becomes cumbersome and lacks a strong evidence-based approach. In this report, we describe a 38-year-old male patient with a history of polysubstance abuse and chronic hepatitis B and hepatitis C infections who presented with acute kidney injury and nephrotic syndrome due to IgA-dominant IRGN without an active concurrent bacterial infection who responded well to plasmapheresis.

IgA-dominant infection-associated glomerulonephritis in the pediatric population

BACKGROUND

IgA-dominant infection-associated glomerulonephritis is well-documented in adults but has not been studied in depth in children. We assessed the incidence of pediatric IgA-dominant infection-associated glomerulonephritis and clinical and kidney biopsy findings.

METHODS

Pediatric native kidney biopsies over a 10-year period with IgA dominance, strong C3, and findings indicative of infection-associated etiology were identified.

RESULTS

We identified 9 cases of IgA-dominant infection-associated glomerulonephritis, 0.8% of pediatric native kidney biopsies. Seven patients presented with elevated creatinine. All had hematuria and proteinuria. Eight patients had clinical evidence of infection: one each with central port infection by methicillin-sensitive Staphylococcus aureus, recurrent streptococcal pharyngitis and recent otitis media, streptococcal pharyngitis demonstrated 8 months after biopsy, suspected streptococcal scalded skin syndrome, and viral gastroenteritis, and three with serologic evidence of Streptococcal infection but no identified site of infection. All but one patient experienced short-term normalization of creatinine and resolution of proteinuria, though two eventually progressed to kidney failure: one 3 years later due to progressive disease and one 11 years later due to focal segmental glomerulosclerosis without concurrent immune deposits.

CONCLUSIONS

Pediatric IgA-dominant infection-associated glomerulonephritis is rare, and generally has a favorable prognosis, contrasting that seen in adults with severe comorbidities. A higher resolution version of the Graphical abstract is available as Supplementary.

Use of Immunosuppressive Therapy in the Treatment of IgA-dominant Infection-related Glomerulonephritis

A 51-year-old Japanese man who experienced colon cancer recurrence following primary and metastatic lesion resection was hospitalized due to facial cellulitis with febrile neutropenia and purpura on his lower extremities after chemotherapy. It was complicated by rapidly progressive glomerulonephritis. He was diagnosed with immunoglobulin A (IgA)-dominant endocapillary proliferative glomerulonephritis based on kidney histology. His glomeruli were positive for the nephritis-associated plasmin receptor, plasmin activity and galactose-deficient IgA1 (Gd-IgA1). A skin biopsy immunofluorescence study revealed IgA deposition within perivascular regions but no Gd-IgA1 deposition. The final diagnosis was IgA-dominant infection-related glomerulonephritis (IRGN). The patient's renal function returned to normal after receiving immunosuppressive therapy that consisted of a glucocorticoid and a cyclophosphamide. Immunosuppressive therapy should be considered in cases of IRGN if the patient's infection is completely under control.

Are there animal models of IgA nephropathy?

Immunoglobulin A (IgA) nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Up to 40% of IgAN patients develop end-stage kidney disease after 15-20 years. Despite the poor prognosis associated with this multifactorial disease, no clear treatment strategy has been identified, primarily due to the lack of understanding of its pathogenesis. Clinical observations indicate that aberrant IgAN immune systems, rather than intrinsic renal abnormalities, may be involved in its pathogenesis. Moreover, nephritogenic IgA and its related immune complexes are considered to be produced not only in the mucosa, but also in systemic immune sites, such as the bone marrow; however, there are numerous challenges to understanding this dynamic and complex immune axis in humans. Thus, several investigators have used experimental animal models. Although there are inter-strain differences in IgA molecules and immune responses between humans and rodents, animal models remain a powerful tool for investigating IgAN's pathogenesis, and the subsequent development of effective treatments. Here, we introduced some classical models of IgAN with or without genetic manipulation and recent translational approaches with some promising models. This includes humanized mouse models expressing human IgA1 and human IgA Fc receptor (CD89) that develops spontaneously the disease. Pre-clinical studies targeting IgA1 are discussed. Together, animal models are very useful tools to study pathophysiology and to validate new therapeutic approaches for IgAN.

Management of systemic risk factors ahead of dental implant therapy: A beard well lathered is half shaved

As the most successful therapy for missing teeth, dental implant has become increasingly prevalent around the world. A lot of papers have reported diverse local risk factors affecting the success and survival rate of dental implants, either for a short or a long period. However, there are also many types of systemic disorders or relatively administrated medicine that may jeopardize the security and success of dental implant treatment. Additionally, the coronavirus disease 2019 pandemic also poses a challenge to dental implant clinicians. Some of these risk factors are clinically common but to some extent unfamiliar to dentists, thus optimal measurements are often lacking when they occur in dental clinics. In this review, we analyze potential systemic risk factors that may affect the success rate of dental implants. Some of them may affect bone mineral density or enhance the likelihood of local infection, thus impeding osseointegration. Others may even systemically increase the risk of the surgery and threaten patients' life. In order to help novices receive high-risk patients who need to get dental implant treatment in a more reasonable way, we accordingly review recent research results and clinical experiments to discuss promising precautions, such as stopping drugs that impact bone mineral density or the operation, and addressing any perturbations on vital signs.

Renal Disease in Cryoglobulinemia

Background

Renal disease in cryoglobulinemia is difficult to grasp and diagnose because it is rare, serological testing is challenging and prone to artifacts, and its morphology is shared by other renal diseases resulting in a spectrum of differential diagnoses. On occasion, a definitive diagnosis cannot even be rendered after immunofluorescence and electron microscopic studies.

Summary

Based on kidney biopsies seen in our routine diagnostic and referral practice, we discuss and illustrate various morphological patterns of renal injury associated with cryoglobulins. We outline key pathophysiologic and clinical aspects associated with cryoglobulinemia induced renal disease and describe morphologic changes with a focus on electron microscopy. We present our practical, morphology-based approach to diagnostic decision-making with special consideration of differential diagnoses and disease mimickers. Since cryoglobulins are rarely tested for prior to kidney biopsy, pathologists and clinicians alike must have a high level of suspicion when interpreting renal biopsies and managing patients.

Key Messages

Cryoglobulinemia-associated glomerulonephritis (GN) is a multifactorial disease which is important to recognize for clinical practice. Morphological features suggestive of cryoglobulinemia-associated GN include a pattern of membranoproliferative GN with abundance of monocytes and the presence of (pseudo)thrombi. By electron microscopy, the main diagnostic features are a prominent infiltration of monocytes/macrophages and the presence of mesangial and subendothelial deposits with frequently curved microtubular/cylindrical and annular substructures.

Infection-Related Glomerulonephritis

Background

There has been a long, storied relationship between various bacterial infections and glomerular injury, which is now encompassed under the term of infection-related glomerulonephritis (GN). The clinical and pathologic manifestations vary depending on the duration, magnitude, and underlying pathogen associated with the inciting infectious process. A brief and acute episode may lead to a self-limiting glomerular manifestation while a chronic or repetitive infection can result in persistent and irreversible injury. In this review, we will discuss the clinical and pathologic findings associated with the infection-related glomerulonephritides.

Summary

An acute exudative GN with an influx of neutrophils is the most characteristic morphologic alteration associated with infection-related glomerular injury. The immunofluorescence staining pattern often reveals prominent complement component C3 deposition in both capillary walls and mesangial regions with or without accompanying immunoglobulin. Large subepithelial electron-dense deposits known as "humps" are the hallmark ultrastructural finding; however, these features can also be present in C3 glomerulopathies, which are often triggered by infections and may have similar underlying abnormalities in alternative pathway complement activation. In addition, other glomerular injuries can simultaneously be present along with infection-related GN, such as diabetic nephropathy, lupus nephritis, or immunoglobulin A nephropathy, constituting a true diagnostic challenge for the pathologist.

Key Messages

Bacterial infection-related GN represents a spectrum of glomerular injury with variable clinical and pathologic presentations. The pathologic findings can show overlap with other glomerular diseases, and different forms of infection-related GN vary in terms of prognosis and treatment approach.

A man with immunoglobulin A nephropathy complicated by infection-related glomerulonephritis with glomerular depositions of nephritis-associated plasmin receptor

A 27-year-old man who developed heavy proteinuria with hematuria and acute kidney injury 2 weeks after a fever was referred to our hospital. Because he had low complements without autoantibodies, we clinically diagnosed him with infection-related glomerulonephritis. The proliferation of mesangial cells and endothelial cells with glomerular deposits of immunoglobulin A and complement 3 was found. Deposition of glomerular nephritis-associated plasmin receptor, a marker of infection-related glomerulonephritis, was also found. In addition, the distribution of nephritis-associated plasmin receptor deposition almost perfectly matched the plasmin activity-positive region. Over 3 months later, his symptoms were resolved, although moderate proteinuria and active urine sediment were persistent. He underwent a second renal biopsy, and the histological findings revealed that he had immunoglobulin A nephropathy. Therefore, we diagnosed him with infection-related glomerulonephritis superimposed on immunoglobulin A nephropathy at the first renal biopsy. The glomerular deposition of nephritis-associated plasmin receptor is a useful marker and may cause worsening urinalysis findings after bacterial infection in cases of chronic glomerulonephritis.

Indian scenario of IgA nephropathy: a systematic review and meta-analysis

BACKGROUND

IgA nephropathy (IgAN) is most common primary glomerulopathy. There are variations in prevalence of IgAN and its clinical features in different studies from India.

AIM

To summarize overall scenario of IgAN in India.

METHODS

In this systematic review, studies related to IgAN and related renal disease were included. Data searched were PubMed, EMBASE, Google scholar, and Cochrane Database from inception to 31st January 2019.

RESULTS

Total 49 studies (N=2480) were included: 21 studies (N=2309) of primary IgAN; 19 studies (N=21) of Secondary IgAN; four studies (N=133) of IgA vasculitis nephropathy (IgAVN); and five studies (N=17) of IgA dominant nephropathy (IgADN). Prevalence of IgAN was 16.5% in India. Age of affected persons was ranging from 27.2±16.7 to 48.6±21.3 years . Male female ratio was 1.8:1. Clinical features of Primary IgAN, IgAVN, IgADN & Secondary IgAN were microscopic hematuria (49.6%, 44.4%, 15.6% & 59.5%), macroscopic hematuria (5.1%, 0.4%,40.9%,& 35.7%), Subnephrotic proteinuria (42.1%, 29.4%, 23.2%, & 52.3%), nephrotic proteinuria (16.0%, 4.4%, 76.8%,& 47.6%), and hypertension (25.8%,18.3%, 35.5%,& 47.6%).. The 24 hours proteinuria was ranging from 2.6±1.5 to 4.7±2.3 gm/day and serum creatinine (mg/dl) was ranging from 0.9±0 to 3.5±3.9 mg/dl. Histolomorphologically, all type of IgAN showed mesangial hypercellularity and Immunofluorescence revealed IgA deposition..

CONCLUSION

The overall prevalence of primary IgAN in India was 16.5%. The subnephrotic proteinuria and microscopic hematuria were common clinical features.

Galactose-deficient IgA1 and nephritis-associated plasmin receptors as markers for IgA-dominant infection-related glomerulonephritis: A case report

RATIONAL

Immunoglobulin A (IgA) nephropathy is a common heterogeneous kidney disease. One of the causes of secondary immunoglobulin A nephropathy is infection-related glomerulonephritis (IRGN), however, its accurate diagnosis is difficult.

PATIENT CONCERNS

We report a rare case of an 82-year-old male presenting rapidly progressive glomerulonephritis. Assessment of a kidney biopsy by light microscopy revealed endocapillary glomerulonephritis with subendothelial deposits, such as wire loop lesions and cellular crescents. Immunofluorescence demonstrated strong staining for IgA and C3 along the glomerular capillary. Additional tests included positive staining for nephritis-associated plasmin receptor and positive plasmin activity in the glomeruli. Moreover, IgA and galactose-deficient IgA1 (Gd-IgA1) staining merged using immunofluorescence, followed by confirmation of high serum levels of Gd-IgA1 (9.3 μg/mL) by ELISA was observed.

DIAGNOSIS

The diagnosis of IgA-dominant IRGN was made.

INTERVENTIONS AND OUTCOMES

We have initiated treatment with intravenous methylprednisolone 500 mg/day for 3 days, followed by oral prednisolone 25 mg/d as rapidly progressive glomerulonephritis. However immunosuppressive therapy was halted because of a poor response, and hemodialysis was initiated.

LESSONS

This is a case of IgA-dominant IRGN patient exhibiting positive glomerular staining for nephritis-associated plasmin receptor accompanied with high titers of serum Gd-IgA1. Our observations suggest that serum and kidney tissue of Gd-IgA1 may be useful for the diagnosis of IgA-dominant IRGN.

Staphylococcus-associated acute glomerulonephritis in a patient with dermatomyositis

Staphylococcus-associated glomerulonephritis (SAGN) occurs as a complication of staphylococcal infection elsewhere in the body. Dermatomyositis (DM) can be associated with glomerulonephritis due to the disease per se. We report a case of a 40-year-old male patient with DM who presented with acute kidney injury, and was initially pulsed with methylprednisolone for 3 days, followed by dexamethasone equivalent to 1 mg/kg/day prednisolone. He was subsequently found to have SAGN on kidney biopsy along with staphylococcus bacteraemia and left knee septic arthritis. With proof of definitive infection, intravenous immunoglobulin 2 g/kg over 2 days was given and steroids were reduced. He was treated with intravenous vancomycin. With treatment, the general condition of the patient improved. On day 38, he developed infective endocarditis and died of congestive heart failure subsequently. Undiagnosed staphylococcal sepsis complicating a rheumatological disease course can lead to complications like SAGN, infective endocarditis and contribute to increased morbidity and mortality, as is exemplified by our case.

Community-Acquired AKI in Asia: An Update

Community-acquired acute kidney injury (CA-AKI) is the dominant form of AKI encountered in developing countries in Asia. Economic disparities, variations in access to health care services, geographic conditions, environmental risk factors, and sociocultural circumstances shape the causes and outcomes of CA-AKI. Infections, drugs, plant and chemical toxins, envenomations, and obstetric complications are common causes of CA-AKI. Previously healthy young individuals who often work outdoors in fields or farms are exposed to a wide variety of work-related or environmental risk factors for CA-AKI. Improving disease definitions, better data, and evolving host-pathogen interactions have changed disease descriptions and presentations over the past 20 years. Among infections, although the incidence of malaria has decreased, the number of cases with dengue and scrub typhus have increased sharply. The recognition of AKI in relation to Plasmodium knowlesi, Plasmodium vivax, scrub typhus, and leptospirosis in areas not traditionally considered at risk, association of infections with the future development of chronic kidney disease, and the role of complement dysregulation in infection-associated AKI are important new findings. Snake-bite-related toxic envenomation continues to be an important cause of AKI in some counties and is a neglected public health problem. On the other hand, significant decreases in the incidence of AKI related to acute diarrheal illness or obstetric causes are signs of hope. Coordinated efforts between administrative stakeholders, society, and health care delivery services at all levels have the potential to propel research and improve outcomes in CA-AKI.

Differentiating Staphylococcus infection-associated glomerulonephritis and primary IgA nephropathy: a mass spectrometry-based exploratory study

Staphylococcus infection-associated glomerulonephritis (SAGN) and primary IgA nephropathy (IgAN) are separate disease entities requiring different treatment approaches. However, overlapping histologic features may cause a diagnostic dilemma. An exploratory proteomic study to identify potential distinguishing biomarkers was performed on formalin fixed paraffin embedded kidney biopsy tissue, using mass spectrometry (HPLC–MS/MS) (n = 27) and immunohistochemistry (IHC) (n = 64), on four main diagnostic groups—SAGN, primary IgAN, acute tubular necrosis (ATN) and normal kidney (baseline transplant biopsies). Spectral counts modeled as a negative binomial distribution were used for statistical comparisons and in silico pathway analysis. Analysis of variance techniques were used to compare groups and the ROC curve to evaluate classification algorithms. The glomerular proteomes of SAGN and IgAN showed remarkable similarities, except for significantly higher levels of monocyte/macrophage proteins in SAGN—mainly lysozyme and S100A9. This finding was confirmed by IHC. In contrast, the tubulointerstitial proteomes were markedly different in IgAN and SAGN, with a lower abundance of metabolic pathway proteins and a higher abundance of extracellular matrix proteins in SAGN. The stress protein transglutaminase-2 (TGM2) was also significantly higher in SAGN. IHC of differentially-expressed glomerular and tubulointerstitial proteins can be used to help discriminate between SAGN and IgAN in ambiguous cases.

Vasculitides and glomerulonephritis associated with Staphylocococcus aureus infective endocarditis: cases reports and mini-review of the literature

We reported two cases of Staphylococcus aureus Infective Endocarditis associated with vasculitides and glomerulonephritis respectively, before conducting an online search of previously published similar cases reports. Twenty five references were selected: 15 cases of glomerulonephritis; 2 cases of vasculitis and 8 cases involving both glomerulonephritis and vasculitis. Vasculitides and glomerulonephritis associated with Staphylococcus aureus definite Infective Endocarditis have been reported since 1976. All cases except one described clinical symptoms occurring before or during initial antibiotics treatment. Except kidney, organs that were more frequently affected by vasculitis process were skin, gastrointestinal tract and peripheral nerve and the vessels involved were small to medium size vessels. When antineutrophil cytoplasmic antibodies were evidenced (6 out of the 25 cases (24%)), kidney was the most frequently affected organ. The most commonly observed pattern in Kidney biopsy was membranoproliferative glomerulonephritis with endocapillary proliferation sometimes associated with extra capillary crescents, whether or not antineutrophil cytoplasmic antibodies were evidenced. Right-sided Infective Endocarditis (especially in intravenous drug users) were overrepresented (14 of the 25 cases (56.0%)) in this review. Besides antibiotics, corticosteroids were the most frequently prescribed immunosuppressive treatment both for vasculitides or glomerulonephritis. KEY MESSAGES Vasculitides and glomerulonephritis associated with Staphylococcus aureus definite Infective Endocarditis have been reported since 1976. Except kidney, organs that were more frequently affected (by small to medium size vessel vasculitis) were skin, gastrointestinal tract and peripheral nerve. The most commonly observed pattern in Kidney biopsy was membranoproliferative glomerulonephritis with endocapillary proliferation and right-sided Infective Endocarditis (especially in intravenous drug users) were overrepresented in this review.

Disparate effects of methicillin-resistant Staphylococcus aureus infection on renal function in IgA-dominant infection-associated glomerulonephritis and menstrual toxic shock syndrome: a case report and literature review

The sudden outbreak of severe acute respiratory syndrome coronavirus 2 pneumonia posed a significant challenge to medical professionals because treatment of critically ill patients requires the efforts of a multidisciplinary team. To highlight this principle, we examined acute kidney injury (AKI) in IgA-dominant infection-associated glomerulonephritis (GN) and menstrual toxic shock syndrome (mTSS). Both GN and mTSS are rare diseases caused by staphylococcal infection, and renal function is frequently impaired. The resulting AKIs are disparate pathological entities driven by distinct immune mechanisms. We begin by describing the case of a diabetic man with pyopneumothorax following methicillin-resistant Staphylococcus aureus (MRSA). He had endocapillary proliferative GN with in situ IgA-dominant immune-complex formation in the mesangium accompanied by complement C3 deposition in the glomerular capillary wall. By contrast, acute tubular necrosis was observed in a case of mTSS; the patient’s immune response was stimulated differently by MRSA enterotoxin and exotoxin resulting in aberrant IgA deposition, complement activation, and insufficient antibody production. As a multidisciplinary communication covering the fields of nephrology, immunology, and pathology, this report may help clinicians to understand these distinct renal lesions and make optimal therapeutic decisions expeditiously.

Clinicopathologic features of infection-related glomerulonephritis with IgA deposits: a French Nationwide study

Background

Infection-related glomerulonephritis with IgA deposits (IRGN-IgA) is a rare disease but it is increasingly reported in the literature. Data regarding epidemiology and outcome are lacking, especially in Europe. We aimed to assess the clinical, pathologic and outcome data of IRGN-IgA.

Methods

Clinical and outcome data from patients from 11 French centers over the 2007–2017 period were collected retrospectively. We reviewed pathologic patterns and immunofluorescence of renal biopsies and evaluated C4d expression in IRGN-IgA. We analyzed the correlation between histological presentation and outcome.

Results

Twenty-seven patients (23 men, mean age: 62 ± 15 years) were included. Twenty-one (78%) had Staphylococcus aureus infection and twelve (44%) were diabetic. At the time of biopsy, 95.2% had haematuria, 48.1% had a serum creatinine level of > 4 mg/dL, and 16% had hypocomplementemia. The most common pathologic presentation included mesangial (88.9%) and endocapillary proliferative glomerulonephritis (88.9%) with interstitial fibrosis and tubular atrophy (IF/TA) (85.1%). Diffuse and global glomerular C4d expression was found in 17.8%, mostly in biopsies with acute or subacute patterns, and was associated with a short delay between infection and renal biopsy compared to segmental and focal staining. After median follow-up of 13.2 months, 23.1% died, 46.2% had persistent renal dysfunction and 15.4% reached end-stage renal disease. Renal outcome was correlated to IF/TA severity.

Conclusions

Infection-related glomerulonephritis with IgA deposits is usually associated with Staphylococcus infections and mainly affects adult men. This entity has a poor prognosis which is correlated to interstitial fibrosis and tubular atrophy severity.

IgA nephropathy: A brief review

IgA nephropathy is a lifelong disease that is the most common primary glomerulopathy worldwide. It has a complicated and incompletely understood pathogenesis that is theorized as a four 'hit' process involving an improperly produced IgA. While it has a variety of histologic appearances, it is diagnosed by the presence of bright IgA deposits within the mesangium as seen on immunofluorescence and mesangial hypercellularity by light microscopy. This brief review explains the varied histologic features that are important in the diagnosis of IgA nephropathy and the calculation of the MEST-C score that was first introduced by the 2009 Oxford Classification working group.

Epidemiology, pathogenesis, treatment and outcomes of infection-associated glomerulonephritis

For over a century, acute 'post-streptococcal glomerulonephritis' (APSGN) was the prototypical form of bacterial infection-associated glomerulonephritis, typically occurring after resolution of infection and a distinct infection-free latent period. Other less common forms of infection-associated glomerulonephritides resulted from persistent bacteraemia in association with subacute bacterial endocarditis and shunt nephritis. However, a major paradigm shift in the epidemiology and bacteriology of infection-associated glomerulonephritides has occurred over the past few decades. The incidence of APSGN has sharply declined in the Western world, whereas the number of Staphylococcus infection-associated glomerulonephritis (SAGN) cases increased owing to a surge in drug-resistant Staphylococcus aureus infections, both in the hospital and community settings. These Staphylococcus infections range from superficial skin infections to deep-seated invasive infections such as endocarditis, which is on the rise among young adults owing to the ongoing intravenous drug use epidemic. SAGN is markedly different from APSGN in terms of its demographic profile, temporal association with active infection and disease outcomes. The diagnosis and management of SAGN is challenging because of the lack of unique histological features, the frequently occult nature of the underlying infection and the older age and co-morbidities in the affected patients. The emergence of multi-drug-resistant bacterial strains further complicates patient treatment.

IgA Nephropathy Flare-Up Mimicking Staphylococcus Post-Infection Glomerulonephritis in Patient with Staphylococcus Aureus Infection Treated with Cefazolin: A Case Report and Brief Review of the Literature

BACKGROUND Glomerulonephritis (GN) associated with post staphylococcus infection (PSIGN) and high serum immunoglobulin A (IgA) has been reported recently. Patients with GN after infection with underlying IgA nephropathy create a challenge to determine the etiology of GN. Therefore, treatment should be accordingly, with steroids used if the IgA nephropathy flare-up is determined to be the etiology. The aim of this case report was to shed light on the difference between PSIGN and IgA nephropathy flare-ups in patients with a history of IgA nephropathy, and how to treat patient cases accordingly. CASE REPORT An 81-year-old male presented to our Emergency Department complaining of increasing pain, swelling, and redness of his left knee since 2 days ago. He had a history of recent methicillin sensitive Staphylococcus aureus (MSSA) left knee arthroplasty infection that was treated with cefazolin, and he had a history of IgA nephropathy diagnosed 1 year ago. CONCLUSIONS In our patient case, renal biopsy studies were not enough to differentiate between PSIGN and IgA nephropathy flare-ups, thus, clinical presentation was important. PSIGN was found to have a delayed onset compared to IgA nephropathy. Lower serum complement 3 (C3) level, heavier proteinuria, and acute renal failure are common with PSIGN compared to IgA nephropathy. Identifying the etiology and treating our patient accordingly with immunosuppressive therapy had a positive impact on the patient, restoring renal function without further damage.

Significance of subepithelial deposits in patients diagnosed with IgA nephropathy

Subepithelial deposits are observed in rare adult IgA nephropathy (IgAN) cases and are a key diagnostic finding in IgA-dominant infection-related glomerulonephritis (IgA-IRGN). Sometimes, it is difficult to distinguish IgA-IRGN from IgAN without a precise clinical history. We hypothesized that some IgA-IRGN cases might be diagnosed as IgAN with subepithelial deposits (IgAN-SD) and aimed to clarify the significance of subepithelial deposits in patients diagnosed with IgAN. We examined 464 patients diagnosed with IgAN at Nagasaki University Hospital and affiliated hospitals between 1996 and 2013. The differences in clinicopathological findings between IgAN-SD and IgAN with no subepithelial deposits (IgAN-NSD) were investigated. In addition to clinical data and typical IgAN pathological features, we analyzed complement levels, immunoglobulin localization, light chain staining patterns, and intramembranous deposits. There were 214 men and 250 women with a mean age of 38.8 ± 18.3 years. Subepithelial deposition was observed in 51 patients (11%). Compared to patients with IgAN-NSD, those with IgAN-SD had significantly lower mean serum protein (6.4 g/dL vs. 6.7 g/dL; p = 0.02), albumin (3.7 g/dL vs. 3.9 g/dL; p = 0.02), and complement (C3) (94 mg/dL vs. 103 mg/dL; p = 0.02) levels. Diffuse mesangial hypercellularity (M) (65% vs. 45%; p<0.01), endocapillary hypercellularity: (E) (43% vs. 28%; p = 0.03), and IgA staining in the glomerular capillary wall (22% vs. 8%; p<0.01) were more common in patients with IgAN-SD. The incidence of light chain lambda predominance was lower in patients with IgAN-SD (47% vs. 63%; p = 0.03). Hump-shaped subepithelial deposits and intramembranous deposits were observed in nine and 17 patients with IgAN-SD, respectively. Patients with IgAN-SD tended to have the characteristics of IgA-IRGN rather than IgAN-NSD. Since the therapeutic strategies for IgA-IRGN differ from those for IgAN, we should review the clinical history and pay careful attention to the clinical course in cases with atypical findings, such as subepithelial deposits.

Vancomycin-Associated Acute Kidney Injury in a Large Veteran Population

BACKGROUND

To determine the association of vancomycin with acute kidney injury (AKI) in relation to its serum concentration value and to examine the risk of AKI in patients treated with vancomycin when compared with a matched cohort of patients receiving non-glycopeptide antibiotics (linezolid/daptomycin).

METHODS

From a cohort of > 3 million US veterans with baseline estimated glomerular filtration rate ≥60 mL/min/1.73 m2, we identified 33,527 patients who received either intravenous vancomycin (n = 22,057) or non-glycopeptide antibiotics (linezolid/daptomycin, n = 11,470). We examined the association of the serum trough vancomycin level recorded within the first 48 h of administration with subsequent AKI in all patients treated with vancomycin and association of vancomycin vs. non-glycopeptide antibiotics use with the risk of incident AKI.

RESULTS

The overall multivariable adjusted ORs of AKI stages 1, 2, and 3 in patients on vancomycin vs. non-glycopeptides were 1.1 (1.1-1.2), 1.2 (1-1.4), and 1.4 (1.1-1.7), respectively. When examined in strata divided by vancomycin trough level, the odds of AKI were similar or lower in patients receiving vancomycin compared to non-glycopeptide antibiotics as long as serum vancomycin levels were ≤20 mg/L. However, in patients with serum vancomycin levels > 20 mg/L, the ORs of AKI stages 1, 2, and 3 in patients on vancomycin vs. non-glycopeptide antibiotics were 1.5 (1.4-1.7), 1.9 (1.5-2.3), and 2.7 (2-3.5), respectively.

CONCLUSIONS

Vancomycin use is associated with a higher risk of AKI when serum levels exceed > 20 mg/L.

IgA-dominant glomerulonephritis with a membranoproliferative pattern of injury

Immunoglobulin A (IgA)-dominant membranoproliferative glomerulonephritis (MPGN) is a descriptive term for renal biopsies in which differential diagnoses of unusual IgA nephropathy (IgAN), infection-related GN, or other etiologies are considered. We sought to understand clinical and pathologic features of this finding. Native kidney biopsies with IgA-dominant immune deposits and diffuse MPGN features without significant exudative features or subepithelial deposits were retrospectively reviewed. Two groups (n = 27, 33 biopsies) were identified: patients with chronic liver disease and those without. Patients without chronic liver disease (n = 15) were men (73%, age 40) who presented with nephrotic-range proteinuria, hematuria, renal insufficiency, negative serologic studies, and no history of infection. At a median interval of 3 years, 11 had available follow-up information. Three (27%) progressed to end-stage renal disease. One had recurrent IgA-dominant GN in the renal allograft less than 1 year posttransplant. Four of 5 patients with repeat biopsies had persistent IgA-dominant MPGN. Patients with chronic liver disease (n = 12) had similar biopsy findings, but 42% had concurrent infections, some occult. At a median interval of 7 weeks, 8 patients (80% of those with follow-up) had died and 2 were dialysis dependent. In conclusion, IgA-dominant MPGN was seen in 2 clinical cohorts in this study. In patients without chronic liver disease, this appears to represent either a unique clinicopathologic entity with a poorer prognosis than IgAN or an aggressive variant of IgAN. Patients with chronic liver disease often have underlying infection, and regardless of treatment, die within 1 year because of complex medical conditions.

A Case of Self-Limiting Crescentic Immunoglobulin A Glomerulonephritis Associated with Sternoclavicular Arthritis

Immunoglobulin (Ig) A glomerulonephritis (GN) is a heterogeneous disease affected by various factors. Genetic and other factors "hit" DNA, causing IgA malformation and ultimately glomerular injury. We describe a rare case of crescentic IgA GN with sternoclavicular (SC) arthritis in a 75-year-old woman. Despite active IgA GN with cellular crescents, the patient achieved remission of IgA GN without glucocorticoid therapy after remission of SC arthritis was achieved. Considering the patient's clinical course, this case suggested a relationship between IgA GN and SC arthritis.

Acute renal failure by rapidly progressive glomerulonephritis with IgA deposition in a patient concomitantly diagnosed with multibacillary Hansen's disease: a case report

Rapidly progressive glomerulonephritis (RPGN) is a renal disease with an extensive differential diagnosis. This paper reports the case of a 55-year-old female patient diagnosed with Hansen's disease with acute progressive renal impairment after developing lower limb pyoderma. The association between Hansen's and kidney disease has been well documented, with glomerulonephritis (GN) ranked as the most common form of renal involvement. Post-infectious glomerulonephritis (PIGN) in adults has been associated with a number of pathogens occurring in diverse sites. The patient described in this case report had RPGN and biopsy findings suggestive of PIGN with C3 and IgA detected on immunofluorescence and kidney injury secondary to recent infection by Staphylococcus, a well-documented manifestation of renal impairment in patients with Hansen's disease.

Staphylococcus-Associated Glomerulonephritis Mimicking Henoch-Schönlein Purpura and Cryoglobulinemic Vasculitis in a Patient With an Epidural Abscess: A Case Report and Brief Review of the Literature

Rationale

Staphylococcus-associated glomerulonephritis (SAGN) is a rare immune complex-mediated glomerulonephritis associated with active Staphylococcus infection. We report a case illustrating the importance of clinical history and kidney biopsy findings in establishing the correct diagnosis.

Presenting concerns of the patient

We report the case of a 64-year-old man with alcohol-associated cirrhosis, type 2 diabetes mellitus, and hypertension who presented to hospital with lower back and abdominal pain, rectal bleeding, a purpuric lower extremity rash, and oliguric acute kidney injury with microscopic hematuria and nephrotic-range proteinuria.

Diagnoses

Skin biopsy revealed IgA leukocytoclastic vasculitis. Serum cryoglobulins were positive and there was hypocomplementemia with a low C3 level. Magnetic resonance imaging of the lumbar spine revealed septic discitis and epidural abscesses caused by a recent Staphylococcus aureus bacteremia. Kidney biopsy showed IgA-dominant and C3-dominant proliferative glomerulonephritis with subepithelial humps in keeping with SAGN.

Interventions

Urgent hemodialysis was initiated along with a prolonged course of intravenous cefazolin.

Outcomes

Remarkably, the patient demonstrated a complete recovery of renal function after 2 months of dialysis dependence and successful treatment of the epidural abscesses.

Lessons learned

This case shows that SAGN can closely mimic the clinical, laboratory, and histological presentation of Henoch-Schönlein Purpura or cryoglobulinemic vasculitis. Clinical history and kidney biopsy, particularly electron microscopic analysis, are essential to establishing the correct diagnosis to avoid the unnecessary and potentially harmful administration of immunosuppression. Despite the typically poor prognosis of SAGN, this case report illustrates that full renal recovery remains possible with supportive care and eradication of the underlying infection.

Staphylococcal Infection-Related Glomerulonephritis With Cryoglobulinemic Features

Introduction

Staphylococcal infection–related glomerulonephritis (GN) has been shown to represent a unique form of infection-related GN that contains IgA-dominant deposits and is often seen concurrently with the bacterial infection. Biopsies commonly reveal an endocapillary proliferative and/or exudative or mesangial proliferative GN. Rare cases have been reported to show cryoglobulin-like features, including hyaline pseudothrombi and wireloop deposits; however, detailed characterization of these cases is lacking.

Methods

The pathology archives from the University of Utah and Sharp Memorial Hospital were reviewed from January 2016 to September 2017 in search of cases with GN containing IgA-dominant deposits and features of cryoglobulinemia.

Results

Of 1965 native kidney biopsies, 5 showed IgA-dominant GN with cryoglobulinemic features. All patients had active staphylococcal infections at the time of biopsy. All presented with acute kidney injury (serum creatinine range: 1.7−6 mg/dl), and all had proteinuria and hematuria. All biopsies showed exudative GN, and 4 biopsies had focal crescents. All had focally prominent hyaline pseudothrombi with or without wireloop deposits, and all showed co-dominant staining for IgA and C3 on immunofluorescence microscopy. Serologic testing for cryoglobulinemia was performed in 3 patients and was transiently positive in 1 patient. Four patients required hemodialysis at last follow-up, whereas 1 patient returned to baseline kidney function.

Conclusion

IgA-dominant GN with cryoglobulinemic features is an uncommon but severe form of glomerular injury in patients with staphylococcal infections. Four of 5 patients had crescentic glomerular injuries, all of whom required hemodialysis at last follow-up. Patients with IgA-dominant GN with features of cryoglobulinemia should be evaluated for active staphylococcal infection.

Staphylococcus Infection-Associated Glomerulonephritis in a Kidney Transplant Patient: Case Report

BACKGROUND

Staphylococcus infection-associated glomerulonephritis is a rare cause of graft dysfunction in kidney transplant. Suspicion should be high in the setting of elevation of serum creatinine, active urinary sediment, with or without hypocomplementemia, and simultaneous Staphylococcus aureus infection. A kidney biopsy is usually diagnostic.

CASE REPORT

A 56-year-old man, who received a kidney transplant in 1998, with basal serum creatinine of 1.2 mg/dL and normal urinary sediment, was admitted to our kidney transplantation unit with graft dysfunction and a urinary tract infection caused by S aureus with septicemia, treated with antibiotics, in the context of recently intensified immunosuppression for a primary immune thrombocytopenia diagnosed 3 weeks earlier. After antibiotic treatment, the patient persisted with graft dysfunction, edema, and hypertension, with a S aureus isolation in the urine culture, active urinary sediment, and low C3. A kidney biopsy was performed, showing diffuse proliferative endocapillary and mesangial glomerulonephritis, with IgA(++) and C3(++) mesangial and endocapillary deposits in immunofluorescence. The patient was treated symptomatically and maintained his regular immunosuppression. At the last follow-up, his serum creatinine value was stable at 2.5 mg/dL.

CONCLUSIONS

The onset of a nephritic syndrome with a simultaneous S aureus infection should lead to suspicion of this uncommon entity, confirmed histologically. Despite its association with poor graft survival, our patient's graft survival remained stable.

Acute glomerulonephritis with large confluent IgA-dominant deposits associated with liver cirrhosis

BACKGROUND

Small glomerular IgA deposits have been reported in patients with liver cirrhosis, mainly as an incidental finding in autopsy studies. We recently encountered nine cirrhotic patients who presented with acute proliferative glomerulonephritis with unusually large, exuberant glomerular immune complex deposits, in the absence of systemic lupus erythematosus (SLE) or monoclonal gammopathy-related kidney disease. Deposits were typically IgA dominant/codominant. Our aim was to further elucidate the etiology, diagnostic pitfalls, and clinical outcomes.

METHODS

We present clinical features and kidney biopsy findings of nine cirrhotic patients with an unusual acute immune complex glomerulonephritis. We also identified native kidney biopsies from all patients with liver cirrhosis at our institution over a 13-year period (January 2004 to December 2016) to evaluate presence of glomerular IgA deposits in them (n = 118).

RESULTS

Six of nine cirrhotic patients with the large immune deposits had a recent/concurrent acute bacterial infection, prompting a diagnosis of infection-associated glomerulonephritis and treatment with antibiotics. In the remaining three patients, no infection was identified and corticosteroids were initiated. Three of nine patients recovered kidney function (one recovered kidney function after liver transplant); three patients developed chronic kidney disease but remained off dialysis; two patients became dialysis-dependent and one patient developed sepsis and expired shortly after biopsy. Within the total cohort of 118 patients with cirrhosis, 67 others also showed IgA deposits, albeit small; and 42 patients had no IgA deposits.

CONCLUSIONS

These cases provide support to the theory that liver dysfunction may compromise clearance of circulating immune complexes, enabling deposition in the kidney. At least in a subset of cirrhotic patients, a superimposed bacterial infection may serve as a "second-hit" and lead to acute glomerulonephritis with exuberant immune complex deposits. Therefore, a trial of antibiotics is recommended and caution is advised before immunosuppressive treatment is offered. Unfortunately, most of these patients have advanced liver failure; therefore both diagnosis and management remain a challenge.

The features in IgA-dominant infection-related glomerulonephritis distinct from IgA nephropathy: a single-center study

BACKGROUND

IgA-dominant infection-related glomerulonephritis (IgA-IRGN) is a unique form of IRGN, which needs to be distinguished from IgA nephropathy (IgAN).

METHODS

Thirteen patients with IgA-IRGN (IgA-IRGN group) and 122 with IgAN (IgAN group) were selected from 1788 patients who underwent kidney biopsy between 2000 and 2015 in Kitano Hospital. Data selected included clinical and serological parameters; light and electron microscope findings; immunofluorescence findings; and prognostic parameters like renal and overall survival and creatinine increase by > 50%. In addition, a 26-patient IgAN cohort (matching-IgAN), matching with IgA-IRGN group with respect to age, sex, estimated glomerular filtration rate (eGFR), and proteinuria was segregated for comparison.

RESULTS

Compared to IgAN group, IgA-IRGN group were older, had lower hemoglobin, higher CRP, lower eGFR, heavier proteinuria, lower serum albumin, and higher serum IgG and IgA levels (p < 0.05). Endocapillary hypercellularity, deposition of immune complexes along the glomerular capillary wall, and subendothelial and subepithelial electron dense deposits were more frequently observed (p < 0.05); and they were more susceptible to renal dysfunction and poorer prognosis. After propensity score-matching, serum albumin was significantly lower in the IgA-IRGN group. Significantly subendothelial and subepithelial deposits were frequently observed in this group. Matching-IgAN group showed relatively advanced sclerotic lesions with more global sclerosis and fibrous crescent.

CONCLUSION

Local inflammation involved glomerular capillary wall in IgA-IRGN, in contrast to relatively chronic and sclerotic renal lesion in IgAN, might result in poorer prognosis in former, even under indistinguishable condition of deteriorated renal function and proteinuria.