Heparin-induced thrombocytopenia following Shiga-toxin-associated hemolytic uremic syndrome: a case report.

BACKGROUND: Up to 50% of cases of Shiga-toxin-producing Escherichia coli hemolytic uremic syndrome occur in adults, and the clinical presentation is variable. Microbiological analyses must be performed in all patients with thrombotic microangiopathy to identify Shiga-toxin-producing Escherichia coli, even in the absence of diarrhea. CASE PRESENTATION: A 79-year-old Caucasian woman was admitted to hospital because of severe proctitis. In the following days, the patient's level of consciousness declined, and she developed acute kidney injury, thrombocytopenia, and hemolytic anemia. Shiga-toxin-producing Escherichia coli was found in fecal cultures, suggesting the diagnosis of hemolytic uremic syndrome. In the following days, her clinical conditions improved, but thrombocytopenia worsened, and the patient developed posterior tibial vein thrombosis. The discordant evolution of thrombocytopenia compared with other clinical and laboratory parameters prompted a new evaluation of its causes. Diagnosis of heparin-induced thrombocytopenia was confirmed by heparin-induced platelet aggregation assay and positive antibodies to platelet factor 4. CONCLUSIONS: A discordant evolution of platelet count in patients with thrombotic microangiopathy requires a systematic reevaluation of the thrombocytopenia.

Poor neutralization and rapid decay of antibodies to SARS-CoV-2 variants in vaccinated dialysis patients.

Patients on dialysis are at risk of severe course of SARS-CoV-2 infection. Understanding the neutralizing activity and coverage of SARS-CoV-2 variants of vaccine-elicited antibodies is required to guide prophylactic and therapeutic COVID-19 interventions in this frail population. By analyzing plasma samples from 130 hemodialysis and 13 peritoneal dialysis patients after two doses of BNT162b2 or mRNA-1273 vaccines, we found that 35% of the patients had low-level or undetectable IgG antibodies to SARS-CoV-2 Spike (S). Neutralizing antibodies against the vaccine-matched SARS-CoV-2 and Delta variant were low or undetectable in 49% and 77% of patients, respectively, and were further reduced against other emerging variants. The fraction of non-responding patients was higher in SARS-CoV-2-naïve hemodialysis patients immunized with BNT162b2 (66%) than those immunized with mRNA-1273 (23%). The reduced neutralizing activity correlated with low antibody avidity. Patients followed up to 7 months after vaccination showed a rapid decay of the antibody response with an average 21- and 10-fold reduction of neutralizing antibodies to vaccine-matched SARS-CoV-2 and Delta variant, which increased the fraction of non-responders to 84% and 90%, respectively. These data indicate that dialysis patients should be prioritized for additional vaccination boosts. Nevertheless, their antibody response to SARS-CoV-2 must be continuously monitored to adopt the best prophylactic and therapeutic strategy.