Lactococcus lactis bacteraemia in a patient on probiotic supplementation therapy

A 59-year-old woman presented with fever and malaise and was found to have Lactococcus lactis bacteraemia. L. lactis infection is rare in humans with few reported cases, with most associated with dairy food product ingestion. The patient reported use of a multistrain over-the-counter probiotic supplement. After isolation of L. lactis from blood culture, the patient was treated empirically with ertapenem and amoxicillin and displayed clinical improvement. She remained well after completion of antibiotic regimen and discontinued probiotic supplementation use. We review the clinical presentation of L. lactis infection including diagnosis, identification and treatment.