D-plus hemolytic uremic syndrome

D-plus Hemolytic Uremic Syndrome (D+HUS), also known as Diarrhea-positive Hemolytic Uremic Syndrome, is a medical condition primarily affecting the kidneys, blood, and, in severe cases, other organs. It is characterized by the triad of hemolytic anemia, acute kidney injury, and thrombocytopenia (low platelet count). This condition is most commonly triggered by an infection with certain strains of Escherichia coli (E. coli), specifically those producing Shiga toxin, such as E. coli O157:H7.

Causes and Pathophysiology

D+HUS is primarily caused by ingestion of food or water contaminated with Shiga toxin-producing E. coli (STEC). Once ingested, these bacteria colonize the gut and produce Shiga toxin, which enters the bloodstream and leads to the destruction of red blood cells, damage to the lining of blood vessels, and acute kidney injury. The damaged blood vessels can cause blood clots to form, leading to further reduction in blood flow to vital organs.

Symptoms

The initial symptoms of D+HUS often include severe abdominal pain, bloody diarrhea, and vomiting, which can occur after an incubation period of 3-4 days following exposure to the bacteria. As the disease progresses, the hemolytic anemia can lead to fatigue, pallor, and shortness of breath, while the kidney injury can result in reduced urine output, fluid retention, and hypertension. Thrombocytopenia can cause easy bruising and bleeding.

Diagnosis

Diagnosis of D+HUS involves a combination of clinical presentation and laboratory tests. Laboratory findings typically include evidence of hemolytic anemia (low hemoglobin levels, elevated lactate dehydrogenase, and presence of schistocytes on blood smear), thrombocytopenia, and signs of kidney injury (elevated creatinine and blood urea nitrogen levels). Stool cultures and tests for Shiga toxin can confirm the presence of STEC infection.

Treatment

Treatment for D+HUS is primarily supportive and includes maintaining fluid and electrolyte balance, managing hypertension, and treating severe anemia and bleeding. In cases of significant kidney injury, dialysis may be required. The use of antibiotics in the treatment of STEC infections that lead to D+HUS is controversial, as they may increase the risk of releasing more Shiga toxin into the bloodstream.

Prevention

Prevention of D+HUS is focused on avoiding exposure to STEC by practicing good hygiene, properly cooking meats, avoiding unpasteurized dairy products and juices, and washing fruits and vegetables thoroughly.

Prognosis

The prognosis for individuals with D+HUS varies. While many recover with appropriate treatment, some may experience long-term kidney damage or other complications. Early recognition and management of the condition are critical to improving outcomes.

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