Acute glomerulonephritis and acute kidney injury associated with 2009 influenza A:H1N1 in an infant

[Influenza A: H1N1 post-viral membranoproliferative glomerulonephritis occurring in aggressive systemic mastocytosis: Case report and literature review]

Systemic mastocytosis is characterised by tissular infiltration and a cytokine storm due to mast cells excessive proliferation and activation. Herein, we report an extraordinary case of AH1N1 influenza post-viral glomerulonephritis occurring in the course of an aggressive systemic mastocytosis with an associated hematological neoplasm. Because of a multisystemic involvement including the liver and lungs, we treated mastocytosis with midostaurin (multiple inhibitor of kinase protein), anti H1/H2 blockers and dexamethasone as first line treatment. One month later and despite vaccination, he developed a severe acute lung injury with respiratory distress due to AH1N1 influenza in association with the nephrotic syndrome. Kidney biopsy disclosed a membranoproliferative glomerulonephritis that was successfully treated with mycophenolate mofetil. Only a few cases of influenza post-viral or post-vaccination glomerulonephritis are documented in the medical literature. This is an exceptional association of uncommon conditions occurring within only a few months in the same patient.

Influenza a H1N1 associated acute glomerulonephritis in an adolescent

Influenza virus primarily affects the respiratory system. It rarely causes extrapulmonary complications, with otitis media and febrile seizures being the most common in children. Acute glomerulonephritis as a complication of H1N1 influenza virus infection has been described only sporadically.

Herein we present a case of acute glomerulonephritis in a previously healthy adolescent, in the context of infection with influenza A H1N1 virus.

A 15-year old adolescent was admitted to our pediatric department due to fever, pharyngitis, cough, vomit, dizziness and fatigue. Based on his symptoms and the seasonal epidemiology, empiric treatment with oseltamivir was initiated while waiting for RT-PCR for influenza virus in pharyngeal swab, which was positive for A H1N1 influenza virus. In the first 24 h of admission, the patient presented macroscopic haematuria, which completely subsided in the following days, along with fever recession. The urine microscopic analysis showed findings compatible with acute glomerulonephritis. The patient remained normotasic while his biochemical profile including renal function, as well as further investigation of hematuria (immunoglobulins, C3, C4, ANA, anti-DNA, U/S) were all normal.

ASTO levels, which were initially above normal (562 IU/ml), did not increase significantly in the following days, and given the fact that C3 levels were constantly within normal limits and pharyngeal culture was negative for pyogenic streptococcus, they were not considered sufficient for poststreptococcal glomerulonephritis diagnosis.

Physicians should be suspicious and include influenza in the differential diagnosis when children present with uncommon symptoms such as hematuria along with even mild respiratory symptoms, during seasonal influenza period.

Mesangial proliferative glomerulonephritis with acute tubule interstitial nephritis leading to acute kidney injury in influenza A (H1N1) infection

Respiratory complications and renal failure are the leading causes for morbidity and mortality due to influenza (H1N1) virus infection. There has been limited information on histopathology of H1N1 influenza-related acute kidney injury (AKI). We describe AKI with H1N1 infection in a 52-year-old female. Renal biopsy showed mesangial proliferative glomerulonephritis with acute tubule interstitial nephritis. Her condition improved rapidly with oseltamivir, fluid replacement, steroid and dialysis. Our case suggests that H1N1 infection may have a causative link to the development of mesangial proliferative glomerulonephritis with acute tubulointerstitial nephritis.

Fecal influenza in mammals: selection of novel variants

In aquatic birds, influenza A viruses mainly replicate in the intestinal tract without significantly affecting the health of the host, but in mammals, they replicate in the respiratory tract and often cause disease. Occasionally, influenza viruses have been detected in stool samples of hospitalized patients and in rectal swabs of naturally or experimentally infected mammals. In this study, we compared the biological and molecular differences among four wild-type avian H1N1 influenza viruses and their corresponding fecal and lung isolates in DBA/2J and BALB/cJ mice. All fecal and lung isolates were more pathogenic than the original wild-type viruses, when inoculated into mice of both strains. The increased virulence was associated with the acquisition of genetic mutations. Most of the novel genotypes emerged as PB2(E627K), HA(F128V), HA(F454L), or HA(H300P) variations, and double mutations frequently occurred in the same isolate. However, influenza virus strain- and host-specific differences were also observed in terms of selected variants. The avian H1N1 virus of shorebird origin appeared to be unique in its ability to rapidly adapt to BALB/cJ mice via the fecal route, compared to the adaptability of the H1N1 virus of mallard origin. Furthermore, a bimodal distribution in fecal shedding was observed in mice infected with the fecal isolates, while a normal distribution was observed after infection with the lung isolates or wild-type virus. Fecal isolates contained HA mutations that increased the activation pH of the HA protein. We conclude that influenza virus variants that emerge in fecal isolates in mammals might influence viral transmission, adaptation to mammals, and viral ecology or evolution.

Acute kidney injury among critically ill patients with pandemic H1N1 influenza A in Canada: cohort study

Background

Canada’s pandemic H1N1 influenza A (pH1N1) outbreak led to a high burden of critical illness. Our objective was to describe the incidence of AKI (acute kidney injury) in these patients and risk factors for AKI, renal replacement therapy (RRT), and mortality.

Methods

From a prospective cohort of critically ill adults with confirmed or probable pH1N1 (16 April 2009–12 April 2010), we abstracted data on demographics, co-morbidities, acute physiology, AKI (defined by RIFLE criteria for Injury or Failure), treatments in the intensive care unit, and clinical outcomes. Univariable and multivariable logistic regression analyses were used to evaluate the associations between clinical characteristics and the outcomes of AKI, RRT, and hospital mortality.

Results

We included 562 patients with pH1N1-related critical illness (479 [85.2%] confirmed, 83 [14.8%] probable]: mean age 48.0 years, 53.4% female, and 13.3% aboriginal. Common co-morbidities included obesity, diabetes, and chronic obstructive pulmonary disease. AKI occurred in 60.9%, with RIFLE categories of Injury (23.0%) and Failure (37.9%). Independent predictors of AKI included obesity (OR 2.94; 95%CI, 1.75-4.91), chronic kidney disease (OR 4.50; 95%CI, 1.46-13.82), APACHE II score (OR per 1-unit increase 1.06; 95%CI, 1.03-1.09), and P_aO₂/F_iO₂ ratio (OR per 10-unit increase 0.98; 95%CI, 0.95-1.00). Of patients with AKI, 24.9% (85/342) received RRT and 25.8% (85/329) died. Independent predictors of RRT were obesity (OR 2.25; 95% CI, 1.14-4.44), day 1 mechanical ventilation (OR 4.09; 95% CI, 1.21-13.84), APACHE II score (OR per 1-unit increase 1.07; 95% CI, 1.03-1.12), and day 1 creatinine (OR per 10 μmol/L increase, 1.06; 95%CI, 1.03-1.10). Development of AKI was not independently associated with hospital mortality.

Conclusion

The incidence of AKI and RRT utilization were high among Canadian patients with critical illness due to pH1N1.

Renal complications of seasonal and pandemic influenza A virus infections

Renal complications of influenza A virus infections are uncommon but can contribute to a deterioration in the patient's condition, which include acute kidney injury (AKI) in critically ill patients, rhabdomyolysis, hemolytic uremic syndrome (HUS), acute glomerulonephritis (AGN), disseminated intravascular coagulation (DIC), Goodpasture's syndrome, and acute tubulointerstitial nephritis (TIN). The clinical characteristics of AKI in critically ill patients with pandemic influenza A(H1N1) 2009 virus (A(H1N1)pdm09) infection are similar to uninfected patients. Underlying conditions associated with AKI include older age, diabetes mellitus, obesity, pregnancy, history of asthma, and chronic kidney disease. Histologic examination of the kidneys from patients with A(H1N1)pdm09 infection who died include acute tubular necrosis (ATN), myoglobin pigment, and DIC. A(H1N1)pdm09 is present in the kidneys of some patients. The clinical characteristics of patients with rhabdomyolysis associated with influenza A include younger age and the frequent occurrence of muscle symptoms. AKI occurs in approximately one third of patients with rhabdomyolysis due to influenza A. HUS is associated with A(H1N1)pdm09 as follows: Streptococcus pneumoniae-associated HUS following A(H1N1)pdm09 infection, HUS triggered by A(H1N1)pdm09 in patients with genetic complement dysregulation, and HUS associated with A(H1N1)pdm09 without known underlying disorder. AGN, Goodpasture's syndrome, and acute TIN are extremely rare complications of influenza A virus infection. Although the pathogenesis underlying renal injuries due to influenza A virus has not been delineated, some hypotheses have been advanced, including ATN due to renal hypoperfusion or rhabdomyolysis, glomerular microthrombosis due to DIC, direct viral injury to the kidney, and an altered immune system with systemic mononuclear cell activation following influenza A virus infections.

A case of tubulointerstitial nephritis in a patient with an influenza H1N1 infection

BACKGROUND

Patients suffering from an H1N1 infection mainly suffer from respiratory symptoms but may also develop symptoms in other organ systems, such as the kidneys.

CASE-DIAGNOSIS/TREATMENT

A 4 ½ year-old boy was admitted with relatively mild respiratory symptoms of H1N1 infection, but developed severe generalized proximal tubular dysfunction with sterile leucocyturia and a reversible rise in serum creatinine. He made a full recovery with supportive therapy.

CONCLUSION

Influenza H1N1 may be associated with acute tubulointerstitial nephritis.