Case report: Lactococcus lactis Bacteremia in an Infant with Kasabach-Merritt Syndrome

Lactococcus lactis is a Gram-positive coccus typically non-pathogenic in humans. Here, we present the case of a 2-month-old infant hospitalized in the neonatal intensive care unit for management of Kasabach-Merritt syndrome, treated with chemotherapy. During hospitalization, the infant developed clinical signs suggestive of severe sepsis alongside abnormal laboratory findings, including a disrupted blood workup (CBC, CRP, etc.). In light of this clinical presentation, blood cultures were performed, revealing Lactococcus lactis bacteremia. The species was identified in two separate blood cultures taken two days apart, confirmed through mass spectrometry analysis (MALDI-TOF). Based on the antibiogram results, treatment with ceftriaxone was initiated and continued for 14 days, resulting in significant clinical improvement. This case highlights the diagnostic and therapeutic challenges encountered in the neonatal setting and underscores the need for heightened awareness of atypical pathogens, particularly in complex clinical situations such as immunocompromised infants.