Alternative C3 pathway activiation in pneumococcal glomerulonephritis

Acute glomerulonephritis with concurrent suspected bacterial pneumonia - is it the tip of the iceberg?

BACKGROUND

Post infectious glomerulonephritis is the most common glomerulopathy in children, occurring several weeks after nephritogenic streptococcal throat or skin infection. Reports of acute glomerulonephritis (AGN) occurring during active bacterial pneumonia in children are rare. The aim of this study was to evaluate the incidence of AGN concurrent with bacterial pneumonia in children.

METHODS

We reviewed records of all children admitted with a diagnosis of pneumonia to the pediatric department in a single tertiary medical center between January 2015 and April 2023. Patients with bacterial pneumonia and concurrent glomerulonephritis were included.

RESULTS

Eleven (0.98%) of 1,123 patients with bacterial pneumonia had concurrent AGN. All were males with a median age of 2.7 years (range 1-13). Mean time from bacterial pneumonia onset to acute glomerulonephritis symptoms was 2.7 ± 1.5 days. Five (45%) patients had evidence of pneumococcal infection. Hypertension was found in 10 (91%) patients. Mean trough eGFR was 43.5 ± 21.4 ml/min/1.73 m2 (range 11-73). Ten patients (91%) had low C3 levels. Median urinary protein-to-creatinine ratio was 2.5 mg/mg (IQR 2.15-14.75). All patients fully recovered. Microscopic hematuria was the last finding to normalize after a median of 29.5 days (IQR 17.25-38).

CONCLUSION

AGN during bacterial pneumonia may be more frequent than previously recognized. Kidney prognosis was excellent in all patients. Prospective studies are needed to evaluate the impact of this condition.

Kidney injury owing to Streptococcus pneumoniae infection in critically ill infants and children: report of four cases

Streptococcus pneumoniae sepsis has high morbidity, particularly if complicated by renal injury. Four patients with S. pneumonia invasive infections complicated by renal disorders are presented. The first case was an 18-month-old girl with pneumococcal empyema complicated by haemolytic uraemic (HUS) syndrome. She made a full recovery after mechanical ventilation, inotropic support and haemodiafiltration. The second was a 4-year-old boy who presented with acute post-infectious glomerulonephritis associated with bilateral pneumococcal pneumonia. He too made a complete recovery. The third was a newborn girl with pneumococcal meningitis complicated by acute respiratory distress syndrome and acute renal failure. The fourth patient was an 8-month-old boy with pneumococcal pneumonia and meningitis complicated by HUS and with fulminant thrombotic thrombocytopenic purpura. Despite full support including mechanical ventilation and haemodiafiltration, he died 4 days after admission. On follow-up, all three survivors recovered completely from their pulmonary symptoms and had normal renal function and cardio-circulatory status in the mid-term.

Staphylococcus-related glomerulonephritis and poststreptococcal glomerulonephritis: why defining "post" is important in understanding and treating infection-related glomerulonephritis

A spate of recent publications describes a newly recognized form of glomerulonephritis associated with active staphylococcal infection. The key kidney biopsy findings, glomerular immunoglobulin A (IgA) deposits dominant or codominant with IgG deposits, resemble those of IgA nephritis. Many authors describe this condition as "postinfectious" and have termed it "poststaphylococcal glomerulonephritis." However, viewed through the prism of poststreptococcal glomerulonephritis, the prefix "post" in poststaphylococcal glomerulonephritis is historically incorrect, illogical, and misleading with regard to choosing therapy. There are numerous reports describing the use of high-dose steroids to treat poststaphylococcal glomerulonephritis. The decision to use steroid therapy suggests that the treating physician believed that the dominant problem was a postinfectious glomerulonephritis, not the infection itself. Unfortunately, steroid therapy in staphylococcus-related glomerulonephritis can precipitate severe staphylococcal sepsis and even death and provides no observable benefits. Poststreptococcal glomerulonephritis is an authentic postinfectious glomerulonephritis; poststaphylococcal glomerulonephritis is not. Making this distinction is important from the perspective of history, pathogenesis, and clinical management.

A case of post-pneumococcal acute glomerulonephritis with glomerular depositions of nephritis-associated plasmin receptor

We report the case of a 12-year-old girl who was referred to our hospital with anuria associated with pneumonia. On admission, the patient's blood test results revealed severe renal failure, hypoproteinemia, and hypocomplementemia. Her urinalysis results revealed hematuria, proteinuria, and a positive titer for Streptococcus pneumoniae. S. pneumoniae was also detected in her sputum and blood cultures. The patient was diagnosed with post-pneumococcal acute glomerulonephritis (AGN) with acute renal failure. A renal biopsy demonstrated the infiltration of neutrophils and mononuclear cells into capillary loops. Immunofluorescence studies showed dominant-positive deposition of C3c along the capillary loops and nephritis-associated plasmin receptor (NAPlr) depositions in the mesangial area and capillary loops. Electron microscopy revealed dense deposits in the glomerular basement membrane without a hump in the subepithelial area. These findings were consistent with endocapillary proliferative glomerulonephritis. AGN associated with pneumococcal infection is very rare. This case suggests that NAPlr is the causative antigen not only of post-streptococcal AGN, but also of post-pneumococcal AGN. To our knowledge, this is the first report that shows a relationship between post-pneumococcal AGN and NAPlr depositions in the glomeruli.

Pneumococcal glomerulonephritis in a healthy child: a case report and literature review

Pneumococcal glomerulonephritis is rarely described in the literature. We report a four-year-old boy who developed acute glomerulonephritis following pneumococcal bacteraemia and submandibular lymphadenitis, and review the published literature. Two weeks after developing acute glomerulonephritis, the patient developed bronchopneumonia with left pleural effusion. However, by the fourth week of admission, his renal function had normalised and lung involvement resolved.

Post-streptococcal acute glomerulonephritis associated with pneumococcal infection

Streptococcus pyogenes is the most common cause of post-infectious glomerulonephritis. Described herein is the case of a 5-year-old girl with febrile post-streptococcal acute glomerulonephritis (PSAGN) associated with pneumococcal bacteremia. The chief complaints were fever and macrohematuria without respiratory symptoms. Urinalysis indicated a protein level of 3+. Serological data showed elevated anti-streptolysin O (ASO) and hypocomplementemia. Blood culture was positive for S. pneumoniae. Her acute renal failure was mild and improved over several days. Although PSAGN was confirmed by elevated ASO and transient hypocomplementemia, the clinical course was consistent with those of several reported cases of AGN associated with pneumococcal infection. To our knowledge, there have been few reports on the relationship between pneumococcal infection and the incidence of PSAGN. We suggest the hypothesis that pneumococcal infection itself could exaggerate the complement reaction leading to PSAGN. It is important to consider PSAGN associated with a microbial infection such as S. pneumoniae when faced with a febrile patient with AGN.

[Pneumonia associated acute glomerulonephritis: a review of 6 cases]

INTRODUCTION

There is an association between pneumonia and acute glomerulonephritis. Both processes start simultaneously.

PATIENTS AND METHODS

A retrospective study of 6 patients admitted to our centre between 2001 and 2010 with acute glomeruolonephritis associated with pneumonia. The result of the smear and tonsil culture was negative and there was an absence of cutaneous infection.

RESULTS

The average age of the patients on admission was 5.9 years with no differences in sex. The diagnosis for pneumonia was made at the time of admission, coinciding with the glomerular symptoms. The most frequent symptoms were fever and macrohaematuria. All had low levels of C3. A significant increase in ASLO was found in 5 cases. The majority of the cases had mild symptoms with the exception of one case of acute renal failure with an initial creatinine of 2.77mg/dL and glomerular filtration rate of 27ml/min/1.73m(2), and two cases with proteinuria in the nephrotic range. All of them progressed satisfactorily without treatment or with minimum diuretic or hypotensive treatment in addition to the appropriate antibiotic treatment with clinical resolution in 7 to 10 days, and C3 returning to normal within a period of less than 4 months.

CONCLUSIONS

There is an association between acute glomerulonephritis and pneumonia, although it is very uncommon. The ASLOs in our series are not specific for Streptoccocus. pyogenes infection. The respiratory and renal prognosis was favourable in all cases.

Acute post-streptococcal glomerulonephritis in children of French Polynesia: a 3-year retrospective study

The aim of this study was to define the current demographic, clinical and prognostic characteristics of acute post-streptococcal glomerulonephritis (APSGN) in French Polynesia and to compare these features with those of other populations. Fifty children, all of whom were <15 years old and had been admitted to the Territorial Hospital of Papeete for APSGN between January 2005 and December 2007, were retrospectively enrolled in the study. Diagnostic criteria were microscopic or macroscopic haematuria, decreased C3 fraction of the complement and evidence of recent streptococcal infection. The annual incidence was 18 cases per 100,000 children <15 years of age in 2007. Most of the children (98%) enrolled in the study were of Polynesian ethnic origin, 27 were male (54%), and the average age at presentation was 6.7 years. Signs of previous respiratory infections were clearly evident in 40% of the children. Most of the patients presented during the rainy season, correlating with the relatively high incidence of skin infections at this time. The majority of patients had proteinuria (98%), with 25% having proteinuria in the nephrotic range (proteinuria/urinary creatinine >3 g/g). The presentation was severe in 22% of the children (congestive cardiac failure, severe hypertension and/or encephalopathy), and renal failure was an initial presenting symptom in 43.7%. The C3 fraction was lower in severe presentations, but the type of haematuria, level of proteinuria and inflammatory syndrome were not correlated with immediate severe forms or with initial renal failure. Haematuria resolved in a mean of 7.7 months and proteinuria in a mean of 3.9 months. None of the children had hypocomplementemia for more than 8 weeks. Acute post-streptococcal glomerulonephritis is endemic among French Polynesians, and they can be considered to be a high-risk population. Despite a high incidence of skin infections, however, the predominance of respiratory infections potentially indicates that French Polynesia is on the way to become a low-incidence area. Systematic detection and treatment of group A Streptococcus should be intensified.

Acute glomerulonephritis associated with pneumonia: a review of three cases

We evaluated the clinical presentation and prognosis of three children with acute glomerulonephritis (AGN) associated with pneumonia. The patient database of Niño Jesús Children's Hospital was analyzed retrospectively (1996-2007) for patients diagnosed at discharge with both pneumonia and AGN. Those with recent pharyngeal or cutaneous infection were excluded. Three patients (1.67, 4.25, and 5 years old, respectively) were selected. All of them had lobar pneumonia, developing both macrohematuria and proteinuria within 24 h after admission. Decreased glomerular filtration rate was found in one patient. Two children developed arterial hypertension and one a slight pleural effusion. Two children had low C3 levels, and one had both low C3 and C4 levels. A Streptococcus pneumoniae serotype 17F was isolated from the blood culture of one patient. On follow-up, all patients had normal blood pressure and renal function with microhematuria persisting long term. Our patients with pneumonia-associated AGN had a good prognosis for both pulmonary and renal involvement.

Glomerulonephritis associated with acute pneumococcal pneumonia: a case report

Streptococcus pyogenes is the most common cause of post-infectious glomerulonephritis. There have been isolated case reports of nephritis following infections with Streptococcus pneumoniae. We report here the case of a 6-year-old white female who presented with blood culture-confirmed pneumococcal pneumonia associated with glomerulonephritis. Her acute renal failure improved over several days, and renal function was normal by 8 weeks post-hospitalization. This case serves to reinforce the concept that other organisms besides Streptococcus pyogenes can trigger a similar post-infectious glomerulonephritis and should be considered in the differential diagnosis of any child who presents with acute glomerulonephritis and respiratory findings. Additionally, pneumococcus group 7 may be a nephritogenic strain and requires further investigation.

Pneumococcal septic arthritis after splenectomy in Felty's syndrome

A patient with Felty's syndrome who developed bilateral knee septic arthritis and septicaemia due to Streptococcus pneumoniae is described. She had had a previous splenectomy for symptomatic thrombocytopenia, having received pneumococcal vaccine before the operation. Measurement of antibody to the 23 vaccine serotypes showed protective concentrations before infection to just two. The infecting serotype was not represented in the vaccine, but a vigorous antibody response to this serotype occurred. The patient also developed glomerulonephritis due to immune complex deposition.

Diagnostic significance of hypocomplementemia

Hypocomplementemia is an important marker for the presence of IC-mediated disease and can be used to assess disease activity. However, in interpreting the clinical significance of hypocomplementemia, the following must be kept in mind: 1) There are numerous non-immunologic conditions that also can cause hypocomplementemia. Furthermore, some of these conditions can cause a multisystem disease that, along with the hypocomplementemia, can closely resemble an IC-mediated systemic vasculitis. Furthermore, these nonimmunologic conditions that lower serum complement levels can complicate the course of patients with inactive IC-mediated disease, spuriously indicating that the disease is active. The most relevant of these differential diagnostic problems are listed in Table 2. 2) There are a few conditions (for example, pregnancy) that can raise serum complement levels, thereby possibly obscuring the presence of a disorder (such as, active SLE) that is lowering complement levels. 3) There are some conditions that might be expected to lower serum complement levels, because of their effect on protein metabolism, but do not. Nephrotic syndrome, and moderately poor nutrition are examples. All of these factors should be considered when interpreting results of serum complement levels in a given patient.

Empyema and mesangiocapillary glomerulonephritis with nephrotic syndrome

Two cases of empyema with nephrotic syndrome are described, a previously unreported association. In one case the nephrotic syndrome resolved with treatment of the empyema. Renal biopsy in both patients showed mesangiocapillary glomerulonephritis and in one case there was evidence of activation of the alternative complement pathway, which is often associated with this histological type of glomerulonephritis. The association between glomerulonephritis and empyema is important because it represents a potentially reversible form of renal disease.

Isolation and characterization of circulating immune complexes from patients with pneumococcal pneumonia

Circulating immune complexes (CIC) were isolated from serum samples from patients with bacteremic and nonbacteremic pneumococcal pneumonia. Overall, 63% (26 of 41) of patients with pneumococcal pneumonia had elevated levels of immunoglobulin G (IgG)-containing CIC. IgM-containing CIC were identified in samples from only three patients. Serum samples from nonbacteremic patients contained significantly higher levels of IgG-containing CIC (96.6 +/- 111.7 micrograms/ml) than did samples from bacteremic patients (31.7 +/- 26.9 micrograms/ml) during week 1 in hospital (P less than 0.05). Immune complexes levels did not correlate with IgG concentrations in serum or anticapsular antibody levels. Immune complexes from nonbacteremic patients had sedimentation coefficients of greater than 19s by density gradient ultracentrifugation. In contrast, CIC from bacteremic patients had smaller coefficients, of between 9s and 14s. Pneumococcal capsular antigens were identified in concentrated dissociated CIC from both patient groups by counterimmunoelectrophoresis.

Antigen detection in the diagnosis and in the prognostic assessment of bacterial pneumonias

Sputum cultures are not helpful in the immediate management of patients with bacterial pneumonia. Sputum Gram stains may provide a presumptive identification of an etiologic agent; this procedure, however, is insensitive (approximately 50%). Consequently, during the last decade, other more sensitive and specific methods of providing a rapid etiologic diagnosis have been sought. This article discusses data on antigen detection in various body fluids by counterimmunoelectrophoresis and agglutination tests. Results from our own laboratory as well as those reported in the literature are presented. The best estimates of antigen detection rates, by the most sensitive assays, in pneumococcal pneumonia, are as follows: serum, 45%-80%; urine, 50%-64%; and sputum, 75%-100%. There is less information for Haemophilus, Klebsiella, and Pseudomonas pneumonias, but the diagnostic yield is approximately 50%-100%. Data will also be presented on the association between free and complexed antigens and morbidity and mortality in pneumococcal pneumonia. Indicators of morbidity discussed include disseminated intravascular coagulation, duration and severity of illness, and occurrence of nephritis.

Glomerular antigens in glomerulonephritis

Ideas on the immunopathogenesis of glomerulonephritis are evolving to embrace a concept of a dynamic and constantly fluctuating involvement of immune reactants in the production of glomerular inflammation. The glomerulus should be regarded as a template around which the antibody-induced inflammatory events that constitute glomerulonephritis are initiated. Such lesions may be produced by direct antibody attack on glomerular antigens of either intrinsic structural or "planted" type, as discussed in this review, or by the deposition of circulating soluble immune complexes containing extraglomerular antigens. These mechanisms are not mutually exclusive and both may play a role in some situations. Intrinsic glomerular antigens are being increasingly better defined as to site, structure, function, and experimental animal models of spontaneous and induced glomerular injury resulting from direct antibody binding to nonclassic GBM capillary wall antigens are available for study. Similar nonclassic GBM antigens are likely to be found of importance in man. Anti-GBM antibody-induced glomerulonephritis continues to be the best understood example of direct attack on the glomerulus by antibody, and its nephritogenic noncollagenous GBM antigenic constituents are being characterized. The incorporation of extraneous substances as "planted" antigens within glomerular structures is now recognized in experimental animal models, and there is suggestive evidence to support the concept in man. Emphasis needs to be placed on the continuing interplay of free antibody and antigen with deposited reactants which, together with complement components, modulate the quality and quantity of the glomerular immune deposits.

Pneumococcal bacteraemia--a study of 75 black children

Seventy-five black children from 0 to ten years old with pneumococcal bacteraemia, who were hospitalized during a one-year period, were studied retrospectively from case records. Half the children were under one year and 68% under two years of age. Sixty-seven per cent were malnourished, 34% severely so. The overall case-fatality-rate was 26.7% being highest in children presenting in autumn (52.4%) and in those with meningitis (54.5%), severe protein-calorie malnutrition (42.8%) or associated infections (61.5%). Host defences against the pneumococcus are discussed, especially in relation to their deficiencies in malnourished and young children. Special mention is made of early-onset neonatal sepsis due to the pneumococcus and of the association between pneumococcal bacteraemia and acute post-streptococcal glomerulonephritis. This study indicates that pneumococcal bacteraemia is a serious infection in children, especially in those with malnutrition and other infections. In view of the emergence of penicillin-resistant strains, its treatment may become more difficult in the future.

Acute and rapidly progressive forms of glomerulonephritis in the elderly

This article presents a comparison of acute glomerular nephritis (AGN) with rapidly progressive glomerular nephritis (RPGN) in patients aged 60 or older. In 7 elderly patients with AGN, the renal disease was preceded by skin infection (4 cases), sore throat (2 cases), or pneumonia (1 case). The 7 patients with RPGN had no history of prior infection. Both AGN and RPGN were manifested clinically as acute renal failure, but the RPGN patients had significantly higher serum creatinine levels and lower hematocrit readings. Hypocomplementemia was a feature only of AGN. The biopsy specimens from patients with RPGN showed crescents in 50--100 percent of the glomeruli, whereas specimens from patients with AGN showed no significant extracapillary proliferation. Six AGN patients recovered and 1 died. Despite dialysis, 4 RPGN patients died and the remaining 3 require maintenance dialysis. It is concluded that AGN in the elderly is more common than previously believed, frequently follows skin infections, and has a reasonably good prognosis. In contrast, RPGN, also not rare in the elderly, has a much worse prognosis.

Alterations in serum opsonic activity and complement levels in pneumococcal disease

Pneumococcal opsonic activity and concentrations of pneumococcal capsular polysaccharide antigen, C3, C4 factor B, C3 and factor B breakdown products were measured in the serum obtained acutely from 12 patients with serious pneumococcal disease. One patient showed markedly reduced pneumococcal opsonic activity, borderline-low C3, and the presence of C3 and factor B breakdown products and died. Although eight additional patients showed depressed levels of C3 or C4 or the presence of C3 or factor B breakdown products, none had reduced pneumococcal opsonic activity. All of the three remaining patients had normal opsonic activity and C3 and C4 levels. Covalescent serum was obtained from eight patients; six had normal C3 and C4 levels, and two had persistent C4 depression. These data show that complement is activated during pneumococcal disease and suggest that extensive complement activation may impair pneumococcal opsonic activity in certain patients and thereby compromise an important host defense mechanism.

Glomerular deposition of complement-control proteins in acute and chronic glomerulonephritis

Acute poststreptococcal glomerulonephritis (AGN) differed from membranoproliferative glomerulonephritis (MPGN) and lupus nephritis (SLE) in that two of the proteins that control the C3b-dependent convertase, beta 1H and the C3bC4b-inactivator cofactor (C3bC4bICo), were frequently absent from the glomerular deposits. In addition, factor B was distributed with C3 in the capillary walls in hypocomplementemic AGN patients. From this, it can be assumed that C3bBb is in the deposits, uninhibited by control proteins as would be predicted for alternative pathway activation. Factor B could not be found in normocomplementemic AGN, was rarely present in MPGN, but was usually present in SLE, most often in the mesangium. In MPGN and SLE, the control proteins were nearly always present in the glomeruli in a distribution like that of C3; IN MPGN they were particularly abundant. Complement profiles indicated an occasional transient reduction in serum C4 level early in AGN. Thus, although there is occasional evidence of early classical activation in AGN, more characteristic is a long period of alternative activation. Serum levels of control proteins did not deviate greatly from normal except for reduced serum beta 1H levels in MPGN type I.

T-cell deficiency in immune complex glomerulonephritis

Mice chronically infected with the virus of lymphocytic choriomeningitis (LCM) develop immune complex glomerulonephritis. Others have shown that adoptive immunization of these mice by the i.p. injection of syngeneic immune spleen cells terminates the chronic viral carrier state. The present studies were designed to define the effector cell from the immune spleen responsible for adoptive immunization and to determine the effect of this procedure upon the immune complex nephritis which occurs in LCM carrier mice. The results indicate that the effector cell in adoptive immunization is a T-cell that functions directly as a killer cell when transferred to LCM carrier mice. Sixteen of nineteen adoptively immunized mice examined had less immune complex material deposited in their glomeruli than control unmanipulated litter mates. These data demonstrate that this animal model of immune complex glomerulonephritis is immunodeficient with respect to LCM virus-specific killer T-cells. Transfer of this cell population to the LCM carrier mouse diminishes the animal's viremia and improves its immune complex nephritis. In view of these observations, it is suggested that the rationale for the use of immunosuppressive therapy in spontaneously occurring glomerulonephritis should be carefully reconsidered.