Abstract
A 69-year-old female with a history of psoriatic arthritis was diagnosed with septic arthritis and started on broad-spectrum antibiotics. She underwent left hip excisional debridement of her prosthetic hip joint which grew group B Streptococcus (S. agalactiae). She was switched to IV ceftriaxone 2 g daily and her hemoglobin decreased to 5.4 g/dL on day 11. Peripheral blood smear showed normochromic normocytic anemia and thrombocytopenia without the presence of schistocytes. Increased lactate dehydrogenase (LDH), decreased haptoglobin and hemoglobin, and positive direct Coombs test (DCT) led to a presumptive diagnosis of drug-induced immune hemolytic anemia (DIIHA). As a result, she was switched from ceftriaxone to IV ertapenem 500 mg every 24 hours and oral prednisone 60 mg for four days during the initial phase. Her hemoglobin, LDH, and haptoglobin trended towards normal limits, further supporting the diagnosis of DIIHA secondary to ceftriaxone.