Microangiopathic hemolytic anemia (MAHA), thrombocytopenia, fever, renal failure, and neurologic symptoms comprise the cardinal features of thrombotic thrombocytopenic purpura and hemolytic uremic syndrome. Etiologies can include medications, infections, cancers, or transplantation. We present a patient with a history of rectal cancer treated with mitomycin-C who developed MAHA, acute kidney injury, and thrombocytopenia 6 months after completing therapy and to did not respond the plasmapheresis or steroids. She was treated with four weekly doses of rituximab with full recovery.

Atypical hemolytic uremic syndrome (aHUS) is a devastating form of renal thrombotic microangiopathy. In the last five years, we have finally witnessed a dramatic improvement in the management of aHUS patients, and three breakthroughs in our understanding of aHUS have led to such an improvement. The first breakthrough was the emergence of a new clinical picture of aHUS (frequency of adult cases, and overall poor renal prognosis despite plasma therapy). The second breakthrough was the identification of complement alternative pathway dysregulation as a major risk factor for aHUS. The third breakthrough was the availability in clinical practice of the first complement inhibitor, the anti-C5 monoclonal antibody, eculizumab. Available data from case series and prospective studies indicate that eculizumab use has dramatically improved the renal prognosis of aHUS. These breakthroughs have prompted the French working group on aHUS to propose a new algorithm for the management of aHUS in children and in adults. This algorithm will evolve as we gain new insights in the pathogenesis and evolution of aHUS in the eculizumab era.

The presence of subtilase-cytotoxin-encoding genes was determined in 397 environmental Escherichia coli strains isolated from water, suspended solids, and sediments sampled from different hydrological and environmental conditions in a California estuary. A total of 7 strains (1.76%) were found to harbor subtilase-cytotoxin-encoding genes. Using primers targeting subA only, we generated PCR amplicons from 2 strains; while using primers targeting the 3' end of SubA downstream to the 5' end of SubB, amplicons of 232 bp were generated from 5 additional strains. The 556 bp subA sequences were almost identical to that in the subtilase-cytotoxin-positive strain ED 591 (98%), while subAB sequences of 2 non-Shiga-toxigenic strains revealed 100% similarity with the Shiga-toxigenic E. coli O113:H21 strain 98NK2 that was isolated from an outbreak of hemolytic uremic syndrome. Additionally, the serogroup O113:H21 was present in this collection of environmental E. coli, and it was found to harbor stx2d, hra1 that encodes the heat resistant agglutinin 1, and a subAB sequence similar to that in the non-Shiga-toxigenic E. coli subtilase cytotoxin strain ED 591. To further understand potential health risks posed by strains encoding SubAB, future epidemiological studies should consider screening isolates for subAB regardless of the presence of Shiga-toxin-encoding genes.

As a model host, the nematode Caenorhabditis elegans has been used for studying unknown pathogen-host interactions and identifying novel virulence factors in bacterial pathogens. Among the bacterial pathogens that can induce death of C. elegans is enterohemorrhagic Escherichia coli (EHEC) O157:H7, a major serotype of EHEC that causes hemorrhagic colitis and hemolytic uremic syndrome in humans and animals. However, it is unknown which EHEC O157:H7 factors are required for nematode death. In this study, bacterial ability to kill C. elegans was tested for several EHEC O157:H7 wild-type and mutant strains missing one virulence-associated factor, including Shiga toxins, enterohemolysin, pO157 (a large virulence plasmid in EHEC O157:H7), Type 3 secretion system, LuxS, and lipopolysaccharide (LPS) O-side chains. Our results demonstrate that only mutants lacking either pO157 or LPS O-side chains cause full attenuation in killing C. elegans. The LPS O-side chain-defective ΔperA mutant strain was not able to colonize in the intestine even at 24h post-feeding with C. elegans, while the wild-type strain began to accumulate and colonize in the intestine as early as 3h post-feeding. A simple complementation of the mutant strain with the plasmid carrying the intact perA gene in trans completely restored the production of LPS O-side chains, as well as the ability to kill C. elegans. Our results show that pO157 and PerA are required for EHEC O157:H7 to kill C. elegans.

Antibody-mediated rejection, be it acute, subacute or chronic, is currently recognized as the major cause of graft loss in kidney transplant recipients. Anti-HLA donor-specific antibodies are deleterious to the graft fate whether they pre-exist to the transplantation or appear in the course of transplantation. The role of complement is therefore prominent in most instances. As well, the role of complement activation is crucial in the recurrence of atypical hemolytic uremic syndrome post-transplantation (aHUS) as well as following ischemia-reperfusion injury leading to delayed graft function. Eculizumab, a fully humanized monoclonal antibody directed against the C5 component of the complement cascade is efficient in chronically and safely blocking complement activation for example in paroxysmal nocturnal hemoglobinuria. In the setting of kidney transplantation, there is convincing but still limited evidence that eculizumab is efficient in preventing both acute and chronic antibody-mediated rejection in highly sensitized recipients requiring desensitization before getting a living donor kidney transplant. Studies are currently ongoing to determine its efficacy and safety in ABO incompatible transplantation, in the prevention of acute and chronic rejection either with a living or a deceased donor kidney as well as in the prevention of delayed graft function. Similar to its efficacy in aHUS on native kidneys, eculizumab prevents or treats recurrence after kidney transplantation. There is still a lot of research to be performed in order to determine precisely the exact indications and the length of treatment with this very active but also very expensive drug that will undoubtedly revolutionize the current management of patients with donor specific antibodies (DSAs) and at risk of HUS recurrence.

Hemolytic uremic syndrome, a life-threatening disease often accompanied by acute renal failure, usually occurs after gastrointestinal infection with Shiga toxin 2 (Stx2)-producing Escherichia coli. Stx2 binds to the glycosphingolipid globotriaosylceramide receptor, expressed by renal epithelial cells, and triggers apoptosis by activating the apoptotic factor Bax. Signaling via the ouabain/Na,K-ATPase/IP3R/NF-κB pathway increases expression of Bcl-xL, an inhibitor of Bax, suggesting that ouabain might protect renal cells from Stx2-triggered apoptosis. Here, exposing rat proximal tubular cells to Stx2 in vitro resulted in massive apoptosis, upregulation of the apoptotic factor Bax, increased cleaved caspase-3, and downregulation of the survival factor Bcl-xL; co-incubation with ouabain prevented all of these effects. Ouabain activated the NF-κB antiapoptotic subunit p65, and the inhibition of p65 DNA binding abolished the antiapoptotic effect of ouabain in Stx2-exposed tubular cells. Furthermore, in vivo, administration of ouabain reversed the imbalance between Bax and Bcl-xL in Stx2-treated mice. Taken together, these results suggest that ouabain can protect the kidney from the apoptotic effects of Stx2.

The complement system contains a great deal of biological "energy". This is demonstrated by the atypical hemolytic uremic syndrome (aHUS), which is a thrombotic microangiopathy (TMA) characterized by endothelial and blood cell damage and thrombotic vascular occlusions. Kidneys and often also other organs (brain, lungs and gastrointestinal tract) are affected. A principal pathophysiological feature in aHUS is a complement attack against endothelial cells and blood cells. This leads to platelet activation and aggregation, hemolysis, prothrombotic and inflammatory changes. The attacks can be triggered by infections, pregnancy, drugs or trauma. Complement-mediated aHUS is distinct from bacterial shiga-toxin (produced e.g. by E. coli O:157 or O:104 serotypes) induced "typical" HUS, thrombotic thrombocytopenic purpura (TTP) associated with ADAMTS13 (an adamalysin enzyme) dysfunction and from a recently described disease related to mutations in intracellular diacylglycerol kinase ε (DGKE). Mutations in proteins that regulate complement (factor H, factor I, MCP/CD46, thrombomodulin) or promote (C3, factor B) amplification of its alternative pathway or anti-factor H antibodies predispose to aHUS. The fundamental defect in aHUS is an excessive complement attack against cellular surfaces. This can be due to 1) an inability to regulate complement on self cell surfaces, 2) hyperactive C3 convertases or 3) complement activation and coagulation promoting changes on cell surfaces. The most common genetic cause is in factor H, where aHUS mutations disrupt its ability to recognize protective polyanions on surfaces where C3b has become attached. Most TMAs are thus characterized by misdirected complement activation affecting endothelial cell and platelet integrity.

Abstract Shiga toxin-producing Escherichia coli (STEC) are associated with foodborne illnesses, including hemolytic uremic syndrome in humans. Cattle and consequently, beef products are considered a major source of STEC. E. coli O157:H7 has been regulated as an adulterant in ground beef since 1996. The United States Department of Agriculture Food Safety and Inspection Service began regulating six additional STEC (O145, O121, O111, O103, O45, and O26) as adulterants in beef trim and raw ground beef in June 2012. Little is known about the presence of STEC in small and very-small beef-processing plants. Therefore, we propose to determine whether small and very-small beef-processing plants are a potential source of non-O157:H7 STEC. Environmental swabs, carcass swabs, hide swabs, and ground beef from eight small and very-small beef-processing plants were obtained from October 2010 to December 2011. A multiplex polymerase chain reaction assay was used to determine the presence of STEC O-groups: O157, O145, O121, O113, O111, O103, O45, and O26 in the samples. Results demonstrated that 56.6% (154/272) of the environmental samples, 35.0% (71/203) of the carcass samples, 85.2% (23/27) of the hide samples, and 17.0% (20/118) of the ground beef samples tested positive for one or more of the serogroups. However, only 7.4% (20/272) of the environmental samples, 4.4% (9/203) of the carcass samples, and 0% (0/118) ground beef samples tested positive for both the serogroup and Shiga toxin genes. Based on this survey, small and very-small beef processors may be a source of non-O157:H7 STEC. The information from this study may be of interest to regulatory officials, researchers, public health personnel, and the beef industry that are interested in the presence of these pathogens in the beef supply.

The increased understanding of the pathophysiology of both atypical hemolytic uremic syndrome (aHUS) and thrombotic thrombocytopenic purpura (TTP) in recent years has led to significant therapeutic advances for both conditions. These advances have placed an increased emphasis on a more rapid differentiation of both disorders which remain clinical diagnoses. In particular, recent data demonstrating the effectiveness of complement inhibition in patients with aHUS have increased the need for a more rapid and accurate differentiation of aHUS and TTP. Previously utilized criteria have used the presence or absence of neurologic or renal injury and the pretreatment ADAMTS13 activity to differentiate aHUS from TTP. The use of presenting clinical symptoms and findings alone to differentiate these conditions is problematic given their overlapping clinical presentations. Similarly, the use of the pretreatment ADAMTS13 activity alone to differentiate aHUS from TTP is also problematic, and could lead to the inappropriate witholding of plasma exchange (PEX) therapy. However, when used collectively, the pretreatment clinical findings (symptoms and laboratory data) and ADAMTS13 activity in the context of the patient's response to PEX therapy can allow for a more effective differentiation of these two disorders in a timely fashion that will allow for the prompt initiation of the most appropriate therapy.

Atypical hemolytic-uremic syndrome is a genetic, life-threatening, chronic disease of complement-mediated thrombotic microangiopathy. Plasma exchange or infusion may transiently maintain normal levels of hematologic measures but does not treat the underlying systemic disease.We conducted two prospective phase 2 trials in which patients with atypical hemolytic-uremic syndrome who were 12 years of age or older received eculizumab for 26 weeks and during long-term extension phases. Patients with low platelet counts and renal damage (in trial 1) and those with renal damage but no decrease in the platelet count of more than 25% for at least 8 weeks during plasma exchange or infusion (in trial 2) were recruited. The primary end points included a change in the platelet count (in trial 1) and thrombotic microangiopathy event-free status (no decrease in the platelet count of >25%, no plasma exchange or infusion, and no initiation of dialysis) (in trial 2).A total of 37 patients (17 in trial 1 and 20 in trial 2) received eculizumab for a median of 64 and 62 weeks, respectively. Eculizumab resulted in increases in the platelet count; in trial 1, the mean increase in the count from baseline to week 26 was 73×10(9) per liter (P<0.001). In trial 2, 80% of the patients had thrombotic microangiopathy event-free status. Eculizumab was associated with significant improvement in all secondary end points, with continuous, time-dependent increases in the estimated glomerular filtration rate (GFR). In trial 1, dialysis was discontinued in 4 of 5 patients. Earlier intervention with eculizumab was associated with significantly greater improvement in the estimated GFR. Eculizumab was also associated with improvement in health-related quality of life. No cumulative toxicity of therapy or serious infection-related adverse events, including meningococcal infections, were observed through the extension period.Eculizumab inhibited complement-mediated thrombotic microangiopathy and was associated with significant time-dependent improvement in renal function in patients with atypical hemolytic-uremic syndrome. (Funded by Alexion Pharmaceuticals; C08-002 ClinicalTrials.gov numbers, NCT00844545 [adults] and NCT00844844 [adolescents]; C08-003 ClinicalTrials.gov numbers, NCT00838513 [adults] and NCT00844428 [adolescents]).