Pneumococcal Induced T-activation with Resultant Thrombotic Microangiopathy

Area of Science:

• Hematology
• Pediatrics
• Infectious Disease

Background:

• Thrombotic microangiopathies involve platelet clots in small blood vessels, leading to red blood cell fragmentation.
• Hemolytic uremic syndrome (HUS) is a severe form of thrombotic microangiopathy, common in children, often linked to bacterial infections like E. coli.
• Certain bacteria, including Streptococcus pneumoniae, can produce neuraminidase, an enzyme implicated in HUS pathogenesis.

Observation:

• A 2-year-old girl with pneumococcal pneumonia and sepsis developed thrombotic microangiopathy and acute kidney injury, consistent with HUS.
• The patient exhibited a positive direct antiglobulin test and polyagglutination with adult serum, indicating T-activation.
• Red blood cells showed reactivity with specific lectins (peanut, soybean), further supporting T-activation due to sialic acid cleavage.

Findings:

• The case illustrates a rare presentation of HUS secondary to Streptococcus pneumoniae infection.
• Neuraminidase activity from the bacteria led to T-activation, exposing the Thomsen-Friedenreich antigen on erythrocytes and other cells.
• Diagnostic challenges exist as standard monoclonal typing antisera may lack anti-T antibodies.

Implications:

• Clinicians must consider T-activation and HUS in children with infections caused by neuraminidase-producing bacteria.
• Early recognition of T-activation is crucial for appropriate management of HUS in this context.
• The risk of transfusion-associated hemolysis in these patients warrants further investigation.