Severe Thrombocytopenia in Actinotignum schaalii Bacteremia: A Case Report With Review of the Literature.

Actinotignum schaalii is an emerging Gram-positive uropathogen that primarily affects older adults with underlying genitourinary abnormalities and can rarely present with severe systemic manifestations. We report the case of a 73-year-old man with a chronic suprapubic catheter who presented with fever, generalized weakness, severe thrombocytopenia, acute kidney injury, and systemic inflammation. Blood cultures grew A. schaalii, while the combination of profound thrombocytopenia and renal dysfunction initially raised concern for disseminated intravascular coagulation (DIC), thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, and other thrombotic microangiopathies. Comprehensive hematologic evaluation, including peripheral blood smear, coagulation studies, hemolysis markers, ADAMTS13 activity, and platelet recovery with treatment of the underlying infection, excluded these competing diagnoses and supported sepsis-associated thrombocytopenia. Computed tomography, renal ultrasonography, and technetium-99m MAG3 diuretic renography demonstrated severe chronic left hydronephrosis with marked cortical thinning and only 14.5% differential renal function, consistent with chronic irreversible obstructive nephropathy rather than acute bilateral renal injury. The patient improved with targeted antimicrobial therapy and supportive management, with resolution of bacteremia, recovery of renal function, and normalization of platelet count. This case highlights the importance of maintaining a broad differential diagnosis for severe thrombocytopenia during bacteremia and integrating microbiologic, hematologic, and radiographic findings to distinguish sepsis-associated thrombocytopenia from life-threatening thrombotic and consumptive disorders, thereby avoiding unnecessary interventions while ensuring timely, appropriate management.