2026 AsPNA临床实践指南：感染相关性肾小球肾炎的管理

Abstract

Infection-related glomerulonephritis (IRGN) is the leading cause of acute glomerulonephritis (GN) in children worldwide, particularly in low- and middle-income countries. To provide evidence-based care, the Glomerular Disease Workgroup of the Asian Pediatric Nephrology Association (AsPNA) convened a panel of experts to develop recommendations on diagnosis, evaluation and management of pediatric IRGN. Following a comprehensive literature search, available evidence was graded using the AAP-GRADE approach, and recommendations finalized through Delphi consensus. The panel recommends diagnosing acute GN in children presenting with hematuria and proteinuria, if accompanied with edema, oliguria, or hypertension. Postinfectious GN is suspected in patients with acute GN with recent streptococcal or staphylococcal infection and transient hypocomplementemia. The evaluation includes urinalysis, kidney function tests, serum albumin, complement C3, blood counts and kidney ultrasonography. Kidney biopsy is required for patients with atypical features, nephrotic syndrome, persistently low C3 beyond 12 weeks, and/or rapidly progressive GN. Therapy is chiefly supportive, including fluid and salt restriction in patients with edema or hypertension, diuretics for volume overload, and calcium channel blockers for stage 2 hypertension. Patients with significant edema, severe hypertension, or acute kidney injury require inpatient monitoring. Patients with staphylococcus-associated GN infective endocarditis associated GN and shunt nephritis require therapy with antibiotics. Immunosuppressive therapy is suggested in patients with crescentic IRGN or rapidly progressive course. All patients with IRGN, particularly those with crescentic GN or rapidly progressive GN, require long-term monitoring of serum creatinine, urinalysis and blood pressure. These guidelines intend to provide a structured, evidence-informed approach for the management of patients with IRGN.

Keywords Crescentic glomerulonephritis· Kidney biopsy· Postinfectious glomerulonephritis

$\boxtimes$ Arvind Bagga arvindbagga@hotmail.com

Pediatric Nephrology

Introduction

Infection-related glomerulonephritis (IRGN) is the leading cause of acute glomerulonephritis (GN) in children worldwide [1, 2]. While acute GN may follow infections with bacteria, viruses, fungi and parasites, IRGN or postinfectious GN (PIGN) is most commonly caused by bacteria, chiefly streptococci and staphylococci [2]. Despite its declining incidence in most developed countries, PIGN remains common among children in low- and middle-income countries. Since there are few guidelines on the diagnostic evaluation and management of the condition, the Glomerular Diseases Working Group of the Asian Pediatric Nephrology Association (AsPNA) assembled a panel of experts to develop guidelines on this topic. We summarize these guidelines that are intended to assist clinicians in care of patients with acute GN, specifically IRGN associated with bacterial infections. This document does not address other etiologies of acute GN, such as IgA nephropathy, IgA vasculitis, C3 glomerulopathy, pauci-immune crescentic GN, and lupus nephritis, or IRGN associated with infection with viruses (hepatitis B or C, HIV, parvovirus, SARS-CoV2) or fungal (coccidioidomycosis, histoplasmosis), protozoal (malaria) and helminthic (schistosomiasis, filariasis) infections. Specific subtypes of IRGN, including staphylococcus-associated GN (SAGN) or IgA-dominant GN, endocarditis-associated nephritis and shunt nephritis are discussed.

Methods

A team of experts from the AsPNA Glomerular Disease Working Group was constituted to review the literature on the epidemiology, diagnostic evaluation, management, and outcomes in children with IRGN. Questions formulated in the Patient, Intervention, Comparator and Outcome (PICO) format were circulated among the group members. A systematic literature search was performed in PubMed and EMBASE databases for studies published until January 2025 using the keywords 'postinfectious glomerulonephritis', 'infection-related glomerulonephritis', 'streptococcal glomerulonephritis', 'staphylococcal glomerulonephritis', 'glomerulonephritis in infective endocarditis', and 'shunt nephritis' (Supplementary Table S1). Randomized controlled trials, uncontrolled interventional or observational studies and registry data on epidemiology, diagnosis and/or management of IRGN, published in the English language, were included. The GRADE system of the American Academy of Pediatrics

was used to rate the quality of evidence as high (A), moderate (B), low (C) or very low (D) [3]. Ungraded statements (indicated by X) are practice points, not supported by sufficient evidence. The strength of advice was graded as level 1 ("We recommend") if most patients should receive the recommended course of action, and level 2 ("We suggest") if different choices are appropriate for different patients.

The evidence was reviewed, and guidelines drafted, discussed and ratified by all members of the expert group. This was followed by consensus among additional experts using the Delphi process. A structured questionnaire based on the GRADE-evaluated evidence was circulated among 41 experts of whom 38 provided responses. Agreement on individual statements ranged from 86 to 100%, with the highest (100%) consensus for recommendations on the use of diuretics and immunosuppression in crescentic GN, and over 90% agreement on nearly all diagnostic, biopsy and therapy-related statements (Supplementary Table S2).

These guidelines are based chiefly on broad expert consensus and are limited by low or very low quality of evidence for most of the statements. Physicians outside the AsPNA and patient representatives were not included in developing this guideline.

# Epidemiology, etiology and pathogenesis

The incidence of acute GN has declined significantly, by an average of 0.75% annually from 1990 to 2019, in high-income countries [1]. The age-standardized prevalence of acute GN in low-middle income and high-income countries is 11.7 and 6.0 per 100,000 population, respectively [1]. PIGN is the chief cause of acute GN in children worldwide, with a median incidence of 24.3 cases per 100,000 person-years [4]. The disease chiefly affects children 3–15 years of age and is twice as common in boys than girls. The mortality rate has remained constant at ~1%, with 97% of deaths occurring in developing countries [4].

While numerous agents are implicated in the pathogenesis of IRGN, infection with Streptococcus pyogenes, a group A streptococcus, is most common. Less frequent pathogens include Streptococcus dysgalactiae subspecies equisimilis (group C or G streptococcus) and Staphylococcus aureus. The term SAGN, however, is reserved for acute GN that accompanies active infection with Staphylococcus spp., and the infection might not be overtly symptomatic. SAGN is increasingly recognized in adults, accounting for 0.8–0.9% of native kidney biopsies, and is particularly associated with diabetes mellitus, alcoholism, HIV infection, malignancy and intravenous drug abuse [2].

PIGN occurs 1–2 weeks after an upper respiratory tract infection and 3–5 weeks following skin infection with

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nephritogenic strains of streptococci [1]. The Lancefield M protein serotypes 12, 4, 1, 25 and 18 are associated with throat infections, occurring most often in the winter and in temperate climates, while M types 49, 42, 2, 57, 60 and 55 cause pyoderma that is more prevalent in the tropics and during summers [1, 2]. However, M protein is not nephritogenic; the chief streptococcal antigens implicated in the pathogenesis of PIGN, in geographically distinct populations, are the nephritis-associated streptococcal plasmin receptor (a glyceraldehyde-3-phosphate dehydrogenase), and streptococcal pyrogenic exotoxin B (a cationic protease and superantigen). These proteins bind to plasmin and glomerular antigens, activate complement and elicit formation of immune complexes [2, 5].

# Diagnostic evaluation

Definitions

$\bullet$ We suggest that the diagnosis of acute GN be considered in patients presenting with hematuria and proteinuria, along with oliguria, edema or hypertension, and no prior clinical or histological evidence of kidney disease. (2C) $\bullet$ We suggest that the diagnosis of postinfectious GN be considered in patients with acute GN who show transient depletion of serum C3 and/or evidence of preceding streptococcal or staphylococcal infection. (2B)

$\bullet$ We suggest that the diagnosis of rapidly progressive glomerulonephritis (RPGN) be made in patients with rapid and severe loss of kidney function over days to weeks, if accompanied by features of acute GN (hematuria, proteinuria, oligoanuria, edema and/or hypertension). (2C)

Rationale

GN, characterized by inflammation and cellular proliferation in glomeruli leading to gross or microscopic hematuria, proteinuria, hypertension and variably reduced kidney function, has a diverse etiology [6]. A subset of patients, typically those with PIGN, anti-neutrophil cytoplasmic antibodies-associated vasculitis and anti-glomerular basement membrane disease, present with acute or rapidly progressive GN, manifest as gross hematuria, facial puffiness or edema, oliguria and hypertension [6]. Rapidly progressive GN may occasionally be the presenting feature of IgA nephropathy and IgA vasculitis [6]. Gross or microscopic hematuria is a cardinal feature of acute GN. Urinalysis findings of proteinuria or albuminuria, dysmorphic red blood cells (> 10–25%), acanthocytes and red cell casts indicate a glomerular origin of hematuria [6–8]. Similar urinary findings may be seen in other GN (IgA nephropathy,

lupus nephritis) and hereditary glomerulopathies (Alport syndrome, MYH9-related glomerulopathy) [8, 9].

PIGN chiefly followed streptococcal infection, but is also reported after staphylococcus and other bacterial infections [10, 11]. This entity is characterized by sudden onset of gross hematuria, oliguria, puffiness and/or hypertension, and is usually preceded by skin or upper respiratory tract infection [2]. Pooled data from 31 studies on 4548 patients with PIGN indicates that hematuria is the most common manifestation, followed by edema and hypertension (Fig. 1). Two-thirds of patients report gross hematuria, and 37% have oliguria. Almost~80% of patients have some degree of proteinuria. Low serum C3 level is the most common complement abnormality, which is typically transient, with hypocomplementemia recovering spontaneously within 12 weeks from onset of symptoms [12, 13]. Evidence of preceding streptococcal infection includes elevated anti-streptolysin O (ASO) titer, observed in ~70% of patients (Fig. 1). Based on these findings, we suggest that diagnosis of PIGN should be considered in patients with evidence of glomerular hematuria with transiently reduced C3, and evidence of previous streptococcal/staphylococcus infection, in the absence of prior kidney disease.

RPGN is a syndrome characterized clinically by gross hematuria and rapid worsening of kidney function over days to weeks, with urinalysis suggesting acute GN, and histology indicating formation of glomerular crescents, a proliferative cellular response of parietal epithelial cells within the Bowman space. For this reason, the terms RPGN and crescentic GN are used interchangeably. Patients with RPGN require prompt evaluation and management in order to improve long-term outcomes [6, 14, 15].

Investigations

$\bullet$ We suggest the following evaluations at presentation in all patients with acute GN: (i) urinalysis, including dipstick and microscopy, (ii) serum creatinine, electrolytes and albumin; (iii) complete blood counts; (iv) complement C3 level; and (v) ultrasound scan of kidneys, ureters and bladder (Table 1). (2C).

Rationale

Urinalysis, including microscopy, should be performed in all patients with suspected acute GN to examine for red blood cells (RBC), white blood cells (WBC), and cellular casts. Urine is also examined for proteinuria, either qualitatively (by dipstick) or quantitatively (spot protein to creatinine ratio, PCR, or 24-h urine protein) (Table 1). Blood levels

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|Parameter|Number of studies|Pooled prevalence (%) (95% CI)|$I^{2}$; P| |---|---|---|---| |Preceding infection|25|79.00 (72.00, 86.00)|95; <0.001| |Pharyngitis or URI|23|49.00 (38.00, 59.00)|96; <0.001| |Skin infection|22|32.00 (22.00, 44.00)|97; <0.001| |Gross/microscopic hematuria|17|91.00 (83.00, 97.00)|97; <0.001| |Gross hematuria|20|66.00 (55.00, 76.00)|96; <0.001| |Oligo-anuria|14|37.00 (18.00, 59.00)|99; <0.001| |Edema|24|78.00 (69.00, 87.00)|97; <0.001| |Hypertension|28|69.00 (60.00, 78.00)|97; <0.001| |Proteinuria|15|80.00 (60.00, 94.00)|99; <0.001| |Nephrotic range proteinuria|10|17.00 (8.00, 28.00)|97; <0.001| |Low C3 level|15|82.00 (69.00, 93.00)|98; <0.001| |Low C4 level|7|20.00 (7.00, 38.00)|96; <0.001| |Elevated ASO titre|17|71.00 (58.00, 82.00)|96; <0.001|

thresholds defined by individual authors. ASO anti-streptolysin O; URI upper respiratory infection

Table 1 Investigations in patients with acute glomerulonephritis

Table 1 Investigations in patients with acute glomerulonephritis

glomerulonephritis

Blood albumin, creatinine, electrolytes Complete blood counts Complement C3 Ultrasonography scan of kidneys, ureters and bladder

Additional $investigations^1$

Indication

Severe AKI

History of preceding infection

History suggesting ongoing infection (e.g., fever)$^{2}$

Systemic symptoms (fever, rash, arthralgia)

Normal complement C3

Anemia or thrombocytopenia

New onset murmur; features of infective endocarditis

AKI acute kidney injury; ANA antinuclear antibodies; ANCA anti-neutrophil cytoplasmic antibodies; DCT direct Coombs test; dsDNA double-stranded DNA; HIV human immunodeficiency virus; LDH lactate dehydrogenase

$^{1}$See Table 2 for indications of kidney biopsy

$^{2}$ Tropical infections (malaria, leptospirosis, scrub typhus, enteric fever) that cause severe AKI should be excluded if urinalysis does not support a diagnosis of acute glomerulonephritis

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 of urea, creatinine and electrolytes are performed to assess for kidney dysfunction [6, 16, 17]. Since activation of the complement pathway is integral to the pathogenesis of immune-complex GN, measuring serum C3 level is a key investigation. Most patients (70–90%) with PIGN show transient reduction in serum C3 level [12, 18, 19] (Fig. 2), which is a classical feature of PIGN and helps differentiate it from other GN, including C3 glomerulopathy and lupus nephritis, where C3 levels remain low [6, 20]. The majority of patients with IgA nephropathy, IgA vasculitis and ANCA-associated vasculitis have normal levels of C3 [6, 17]. Ultrasound scan of kidneys, ureters and bladder is useful in excluding chronic kidney disease (CKD) as well as non-glomerular causes of hematuria, such as urolithiasis and kidney cysts.

Considering the clinical features and results of initial investigations, patients with acute GN might need further evaluation (Table 1). Documentation of serological evidence of preceding streptococcal infection by ASO and/or anti-deoxyribonuclease (DNAse)-B is useful, as cultures are unlikely to be positive at the time of presentation [21–23]. ASO titers are elevated 2–4 weeks following streptococcal infection and remain elevated for 6–8 months. The peak of ASO titers may be blunted by antibiotic therapy. Combining both ASO and anti-DNAse-B provides better sensitivity (96%) and specificity (89%), than either test alone [22]. However, there are no universally accepted upper limits of normal for ASO and anti-DNAse-B, since they are influenced by

age, geographical location and seasonal variation [23]. Evidence supports the preference for paired samples demonstrating rising antibody titers (fourfold rise over ~4 weeks) over a single value to confirm a diagnosis of recent group A streptococcal infection [23–25].

Patients with features of ongoing infection need evaluation for its source, by blood culture, fluid culture, and/or imaging [2]. Patients with systemic manifestations, including fever, arthritis, skin rash, lymphadenopathy, and/or organomegaly, may have an underlying systemic disease, e.g., systemic lupus erythematosus or vasculitis, resulting in acute GN. Since the initial features of hemolytic uremic syndrome can mimic acute GN, complete blood counts and peripheral smear examination are performed to rule out microangiopathic hemolytic anemia and thrombocytopenia [26].

Kidney biopsy

* We suggest performing kidney biopsy for patients with acute GN who meet any of the indications listed in Table 2. (2D) * We recommend that all kidney biopsy specimens be assessed by light microscopy and immunofluorescence. (1C) * We suggest that the presence of crescent (s) be considered evidence of severe glomerular injury. (2B)

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At presentation

Rapidly progressive glomerulonephritis Systemic features, e.g., fever, skin rash, arthralgias/arthritis Nephrotic state (nephrotic range proteinuria, hypoalbuminemia and edema) Normal complement C3 During follow up Persistence of Severe acute kidney injury (AKI)$^{1}$ or oliguria beyond 7–10 days Gross hematuria beyond 2–3 weeks Nephrotic range proteinuria beyond 2–3 weeks Hypocomplementemia (low complement C3) beyond 12 weeks Proteinuria (spot urine PCR >0.5 mg/mg) beyond 6 months Microscopic hematuria beyond 1 year Recurrence of symptoms (gross hematuria, edema, AKI) after a symptom-free interval

PCR protein creatinine ratio

$^{1}$Defined as stage 2-3 AKI, as per KDIGO criteria

$\bullet$ We suggest that attempts be made to evaluate all kidney biopsy specimens by electron microscopy. (X)

Rationale

PIGN is usually a self-limiting disease that resolves over 2–6 weeks in most patients. While edema, gross hematuria and hypertension resolve spontaneously within 7–10 days from onset of symptoms [27, 28], serum levels of C3 return to baseline by 3 months in most cases [12, 13, 18]. Proteinuria usually resolves earlier than microscopic hematuria [29, 30]; the latter might persist up to 12 months in some patients (Fig. 2).

Most patients with typical clinical manifestations of PIGN do not require a kidney biopsy. A proportion of patients with acute GN require kidney biopsy, chiefly to exclude conditions such as C3 glomerulopathy, IgA nephropathy, lupus nephritis, and systemic vasculitis, that require specific management, and to aid in prognosis. All children presenting with RPGN should undergo kidney biopsy to determine the underlying histology and plan further therapy [27]. A biopsy is also necessary in patients with associated systemic manifestations (fever, joint pain, rash), nephrotic state or normal complement C3 at initial presentation, persistence of severe acute kidney injury (AKI) or oliguria beyond 7–10 days, gross hematuria or nephrotic range proteinuria persisting beyond 2–3 weeks, and hypocomplementemia persisting beyond 12 weeks from onset [29, 30]. Patients with persistence of microscopic hematuria beyond 12 months should be considered for genetic testing to diagnose inherited nephropathies such as Alport syndrome.

The kidney biopsy specimen should be evaluated by light and immunofluorescence microscopy to differentiate PIGN from other conditions such as IgA nephropathy, lupus nephritis and C3 glomerulopathy (Supplementary Table S3) [2, 6, 17]. Findings on light microscopy vary, based on the timing of the kidney biopsy since the onset of symptoms [6, 27]. Histologically, PIGN is characterized by a diffuse proliferative pattern of injury with neutrophilic exudation and endocapillary and mesangial hypercellularity (Fig. 3 (A, B)). The capillary walls are thin and pliable without evidence of remodeling. Immunofluorescence examination shows bright staining for mesangial and capillary wall IgG and C3 (Fig. 3 (D, E), Fig. 4 (A, B)). If the biopsy is performed late in the disease course, it may show only residual mesangial hypercellularity with isolated C3 staining [27].

Crescents may be seen in patients with PIGN presenting with RPGN (Fig. 3 (C)). While the term crescentic GN is reserved for involvement of more than 50% glomeruli with crescents, the presence of even a single crescent might indicate severe disease [15, 31]. A study from North America suggests that the presence of more than 43% crescents is associated with risk of kidney failure on the long-term [31]. A recent meta-analysis showed that patients with crescents in more than 50% glomeruli were at highest risk of progression to kidney failure [32].

The presence of electron dense subepithelial deposits is characteristic of PIGN on electron microscopy (Fig. 3 (F)). Small mesangial and subendothelial deposits may also be identified (Fig. 3 (F)) [6]. Electron microscopy helps differentiate between PIGN and C3 glomerulopathy, particularly when the immunofluorescence profile indicates isolated or dominant C3 (Fig. 4 (C, D)). Biopsy findings

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 differentiating PIGN from other causes of acute GN are described in Supplementary Table S3.

Treatment

$\bullet$ We suggest salt and fluid restriction in patients with edema and/or hypertension. (X) $\bullet$ We suggest hospital admission for patients with significant edema, severe AKI and/or stage 2 hypertension. (X) $\bullet$ We recommend monitoring of blood pressure, urine output, and serum creatinine in all patients with acute GN in a hospital setting. (X) $\bullet$ In patients with acute GN with hypertension, and fluid overload or edema, we suggest using furosemide as the first antihypertensive agent. We also suggest using calcium channel blockers in patients with stage 2 hypertension. (2B)

forming a cellular crescent, as indicated by blue arrow (Jones silver methenamine; 20X). (D) Low power immunofluorescence shows diffuse involvement of the glomeruli with coarse granular capillary wall deposits of IgG. Note the variability in staining between glomeruli (FITC-IgG; 10X). (E) On closer view, the 'garland' pattern and 'lumpy bumpy' nature of the deposits are noted (FITC-IgG; 20X). (F) Subepithelial 'humps' (blue arrows) noted on transmission electron microscopy are characteristic of postinfectious GN (uranyl acetate, lead citrate; 1000X)

Rationale

The majority of patients with acute GN have mild disease and are managed on an outpatient basis. Patients presenting with RPGN, and those with significant edema (> 5-7% weight gain), severe hypertension and/or severe AKI require hospitalization. Such patients require monitoring of blood pressure, fluid balance, serum creatinine and electrolytes. Since hypertension in PIGN is mediated chiefly by sodium and water retention, fluid and salt restriction (1-2 mEq/kg/day of sodium) is the cornerstone of management. Furosemide is suggested as the first-line agent for managing hypertension in these patients [2, 33, 34]. Thiazide diuretics can also be used, but their efficacy is limited in patients with impaired kidney function [28]. Some patients with severe hypertension require additional medications to control blood pressure. Calcium channel blockers (e.g., amlodipine) are effective agents [35]. While a study found captopril to be more effective than the combination of reserpine and furosemide [36], we suggest avoiding angiotensin converting enzyme inhibitors (ACEi), in view of their side effects of

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Fig. 4 Interpretation of the immunofluorescence panel in acute glomerulonephritis (GN) (A, B) The finding of significant IgG deposits in the presence of C3 deposition is considered indicative of typical postinfectious GN. (FITC C3 and IgG; 20X). (C, D) The finding of predominant or isolated C3 deposits raises the suspicion for C3 glomerulopathy, which includes C3 GN and dense deposit disease, but may also be seen in atypical cases of postinfectious GN. In these cases, electron microscopic evaluation and close clinical follow up are recommended (FITC C3, IgG; 20X)

 hyperkalemia and worsening of kidney function. A study that compared nifedipine and captopril showed similar efficacy but the former was associated with faster blood pressure control and brief hospital stay [37].

Patients with PIGN presenting with hypertensive emergency should be managed with intravenous (IV) agents such as sodium nitroprusside or labetalol, to gradually reduce blood pressure to the target level [38, 39]. A small proportion of patients may require kidney support therapy (KST). Indications for initiating KST include refractory hyperkalemia, metabolic acidosis, fluid overload (> 10–15%) not responding to diuretics, and uremic complications [40]. The choice of KST modality chiefly depends on feasibility considerations and clinician expertise.

Rapidly progressive GN

$\bullet$ In patients with crescentic GN, we suggest induction therapy with IV methylprednisolone and IV cyclophosphamide. (2C) $\bullet$ We suggest maintenance therapy with oral prednisolone with mycophenolate mofetil or azathioprine for 6–12 months in patients with crescentic GN. (2D) $\bullet$ In patients presenting with RPGN and diffuse proliferation (without crescents) on kidney histology, we suggest treatment with IV methylprednisolone with

or without IV cyclophosphamide, followed by oral prednisolone for 6–12 months. (X)

Rationale

While most patients with PIGN recover kidney function rapidly and do not require immunosuppression, a small proportion, presenting with features of RPGN, is less likely to recover spontaneously. Since PIGN is an immune-complex mediated GN, the use of immunosuppressive therapy might hasten recovery of kidney function and improve long-term outcomes. However, the evidence for use of immunosuppressive therapy in such patients is limited. An RCT in children with biopsy-proven PIGN with crescents showed that creatinine clearance improved faster in patients randomized to receive immunosuppression compared to the control group; however, kidney functions were similar between groups at 3 and 6 months [29]. Two retrospective studies in the adult population failed to show improved outcomes with steroid therapy in patients with crescentic PIGN [41, 42]. A recent trial in 52 adult patients did not indicate better kidney function recovery with with methylprednisolone pulses compared to supportive management [43].

Despite limited evidence to support use of immunosuppression, the guideline panel suggests that patients with PIGN who have crescentic GN on biopsy be managed with IV immunosuppressive agents. We suggest

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initial treatment with IV methylprednisolone (10–20 mg/kg daily for 3–6 doses) and IV cyclophosphamide (500–750 mg/m$^{2}$ every 3–4 weeks for 6 doses) to suppress inflammation and limit kidney damage (Table 3). Further, these patients may be considered for therapy with oral prednisolone and mycophenolate mofetil or azathioprine for the next 6–12 months, depending on the degree and pace of recovery of kidney function during follow-up (Table 3). We also suggest that patients presenting with RPGN and with histological evidence of diffuse proliferation (without crescents) receive IV methylprednisolone pulses. Further therapy, including IV cyclophosphamide pulses and maintenance immunosuppression, may be on a case-by-case basis, considering the severity of kidney injury, histology, and findings on urinalysis during follow-up.

Occasionally, kidney biopsy in patients presenting as IRGN may reveal the diagnosis of IgA nephropathy or C3 glomerulopathy. For further management of these entities, the physician may refer to appropriate guidelines [44, 45].

Antibiotic therapy

$\bullet$ We suggest not to administer antibiotic therapy in patients with postinfectious GN (PIGN). (2B)

Rationale

The risk of PIGN in children infected with Streptococcus pyogenes is influenced by the streptococcal strain, site of infection, and host immune responses [2]. The incidence and severity of PIGN are high during epidemic outbreaks. Eradicating the infection with antibiotics in affected individuals and prophylactic antibiotics in family members might prevent the transmission of nephritogenic strains [2, 46, 47]. While limited studies and a meta-analysis suggest that antibiotics diminish the risk and severity of PIGN, this evidence is of low certainty [48–50]. Antimicrobial therapy is only useful in patients with active streptococcal infection; it is not needed in patients with PIGN, since the infection has usually subsided by the time the disease manifests clinically [2].

Outcomes

$\bullet$ We suggest that all patients with IRGN be followed up, with monitoring of serum creatinine, and for proteinuria, microscopic hematuria and hypertension. (X)

Rationale

Recovery from the acute phase of PIGN is excellent. However, patients with PIGN require long-term follow-up,

as a small proportion of cases may develop CKD [51]. While earlier studies indicated a benign course with no long-term complications [52, 53], some reports suggest that 5–15% of patients with PIGN may have urinary abnormalities and progression to CKD [54, 55]. Hence, we advise that patients with IRGN, especially those presenting with RPGN or severe AKI, are assessed every 6–12 months with serum creatinine, urinalysis, and blood pressure. Patients presenting with rapidly progressive GN or with histology suggesting crescentic GN, and those with persistent proteinuria, hypertension or low GFR at 6–12 months follow-up, require follow-up for 4–5 years or longer. In contrast, monitoring for 6–12 months is sufficient for patients presenting with typical features of PIGN and complete recovery. Risk factors for developing CKD are persistent proteinuria, kidney dysfunction at presentation, and crescentic histology on the initial biopsy [28].

Staphylococcus-associated GN (SAGN)

$\bullet$ We suggest that the diagnosis of SAGN be based on: (i) evidence of ongoing staphylococcus infection, (ii) presence of AKI, (iii) glomerular hematuria and nephrotic range proteinuria, (iv) low C3, (v) proliferative GN on light microscopy, and (vi) C3 with or without IgA deposits on immunofluorescence microscopy. (2C)

$\bullet$ We recommend that patients with SAGN receive antibiotic therapy to eliminate the underlying infection. (1B)

* We suggest not using immunosuppressive medications during active infection for treatment of SAGN. (2C)

Rationale

SAGN is chiefly diagnosed in adults and uncommonly affects children [2, 56]. SAGN in adult patients is chiefly reported in the context of diabetes mellitus; risk factors reported in adolescents and children include IV drug use, invasive procedures and dental abscesses. While evidence of staphylococcal infection is apparent in presence of pyoderma or cellulitis, determining deep-seated infections, such as osteomyelitis, endocarditis and dental abscess, may be difficult. A few patients have skin rash with leukocytoclastic vasculitis similar to that observed in IgA vasculitis [57].

Patients without an obvious focus of infection require detailed evaluation for deep-seated infections. Not all patients with SAGN mount fever and blood culture may not grow the organism. While hypocomplementemia is common, a small proportion of patients also show positive anti-neutrophil cytoplasmic antibodies [58]. Kidney biopsy may be considered in patients with persistent kidney dysfunction despite elimination of active staphylococcal

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Table 3 Medications used in the management of patients with acute glomerulopenphritis Drug Nethyldramisolone 10-20 mg/kg IV per dose; daily for 3-6 doses Methyldramisolone 1 mg/kg IV per dose; daily for 3-6 doses for 6-doss Prednisolone 1000-1200 mg/kg 20-1200 mg/kg in two divided doses for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for 6-doss for

HbA le glycosylated hemoglobin; IV intravenous; PO por oral, Reduce dose by 2.5 mg/kg if estimated glomerular filtration rate (eGFR) < 30 ml/min per 1.73 m$^{2}$

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infection. Histologically, the most common finding is of mesangioproliferative or endocapillary proliferative GN with or without crescents (Supplementary Table S3). Mesangial deposition of IgA and C3 is characteristic of SAGN; deposits along the capillary walls are also observed. Electron microscopy reveals electron-dense mesangial deposits; while subepithelial humps may be present, they are not typical [58]. The absence of documented staphylococcal infection, heavy proteinuria or crescents, and normal complement C3 level help distinguish between IgA nephropathy and SAGN.

The primary aim of therapy in patients with SAGN is to eliminate the infection using appropriate antibiotics, administered for 4–6 weeks. Supportive therapy in patients with SAGN is similar to that for PIGN. The role of immunosuppression is controversial, since corticosteroids may exacerbate the underlying infection [59]. In a recent review, while remission rates were similar in patients treated with corticosteroids or not, mortality was higher in the former group [59]. If biopsy findings show active GN, and active infection is eliminated, immunosuppression may be considered to hasten the recovery of kidney function [56, 60, 61]. Limited data suggest better outcomes in pediatric compared to adult patients with SAGN [56, 59]. However, progression to kidney failure in patients with SAGN is higher than in those with PIGN [56, 59].

Endocarditis-associated GN

$\bullet$ We recommend that patients with infective endocarditis-associated GN receive prolonged parenteral antibiotic therapy to eradicate the infection. (X) $\bullet$ We suggest that immunosuppressive therapy be reserved for patients with crescentic glomerulonephritis, after active infection has been controlled. (X)

Rationale

GN associated with infective endocarditis is common in adults with IV drug abuse. While AKI is the most common clinical feature, fever, anemia, splenomegaly and rash are important clues to the diaps [62]. Other findings of infective endocarditis, such as Osler nodules, Janeway lesions and splinter hemorrhages, are uncommon. Serum C3 levels are depressed in more than half of patients with endocarditis-associated GN; anti-neutrophil cytoplasmic antibodies may be present in a proportion of patients [2, 63, 64]. Histological findings vary, from focal crescentic GN to membranoproliferative GN (Supplementary Table S3).

The cornerstone of management of endocarditis-associated GN is prolonged intravenous antibiotics to treat the underlying infection. Supportive care is similar

to that for acute GN. Refractory cases might benefit from replacement of an infected heart valve. Immunosuppressive therapy is best deferred until infection has been adequately controlled even in patients with crescentic or necrotizing GN on histopathology [2, 65–67], Nevertheless, a case series from the Mayo Clinic reported successful use of immunosuppression in one-third of patients with endocarditis-associated GN [62], suggesting that a subset of patients might benefit from careful use of immunosuppression to hasten kidney recovery [68–71]. This might be particularly true for patients with positive anti-neutrophil cytoplasmic antibodies [64]. While most studies report use of corticosteroids, cyclophosphamide has also been administered [62, 68, 69, 72]. Long-term outcomes are unfavorable, with less than one-third of patients showing complete kidney recovery [2, 73].

Shunt nephritis

* We recommend that shunt nephritis be managed with appropriate antibiotics to eradicate the underlying infection and prompt removal or replacement of the infected shunt. (X)

Rationale

Shunt nephritis represents an immune complex-mediated GN that occurs as a systemic complication of chronically infected cerebrospinal fluid (CSF) shunts, most commonly venticuloatrial (VA) shunts. The condition is reported in approximately 0.7–2% of patients with infected VA shunts, and only rarely with ventriculoperitoneal (VP) shunts [74, 75]. Staphylococcus epidermidis is the predominant pathogen, accounting for nearly 75% of cases. Staphylococcus aureus, Corynebacterium sp., Listeria monocytogenes, Pseudomonas aeruginosa, and Propionibacterium acnes have also been implicated [74, 76].

Shunt nephritis usually presents several months following shunt placement. Initial features include shunt malfunction, fever, malaise, and other systemic symptoms. This is followed by kidney involvement, characterized by microscopic or gross hematuria, nephrotic range proteinuria, and varying degrees of AKI [77]. Laboratory investigations reveal hypocomplementemia, elevated serum IgM, and circulating immune complexes, consistent with an immune complex-mediated process [77]. Kidney biopsy typically demonstrates membranoproliferative GN, characterized by mesangial expansion, endocapillary proliferation and, on electron microscopy, subendothelial immune deposits.

The cornerstone of management is the eradication of the infection through use of appropriate antibiotics and removal

Pediatric Nephrology

of the antigenic source, i.e., the infected shunt. Numerous case series and reviews have documented that this approach leads to gradual improvement in kidney function [75, 78]. Conversely, if the shunt is retained, there is continued immune activation, leading to irreversible glomerular damage and progression to CKD. Timely identification of shunt infection and prompt removal of the infected device are critical to prevent ongoing antigenic stimulation and facilitate kidney recovery [77].

Conclusions

IRGN remains the most frequent cause of acute GN in children, particularly in resource-limited settings. These clinical practice guidelines are based on systematic evidence review and consensus among experts by the Delphi method. Key recommendations emphasize that diagnosis of IRGN be based on clinical features and investigations, and attention to atypical findings that merit consideration of alternative diagnoses and/or kidney biopsy. The management is supportive with fluid and salt restriction, duiretics for volume overload, and calcium channel blockers for hypertension. Antibiotics are used only in patients with active streptococcal infection. Immunosuppression is suggested for crescentic IRGN or rapidly progressive GN. The need for long-term follow up in patients with IRGN is emphasized, particularly for patients with severe AKI. We hope that these guidelines will help standardize care and improve outcomes of pediatric IRGN across diverse settings.

Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/s00467-026-07146-4.

Author contributions AS, AB and JK conceived the idea of the manuscript. JM, SK and AS were involved in the review of literature and preparation of background document; JM, AS, SK and AB helped in synthesizing the data and drafting the recommendation; JM, AS and AB drafted the manuscript; all authors critically revised the manuscript and approved the final version of the manuscript.

Funding No funding was received by the authors for this work.

Declarations

Conflict of interest None of the authors have any financial or intellectual conflict of interest.

Informed consent Not applicable.

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