Probiotic strains of Lactobacillus are currently used in a variety of clinical practices with limited evidence to support their use. Lactobacillus species are a normal part of gastrointestinal flora, and bacteremia with probiotic strains of Lactobacillus is very uncommon. We describe a case of Lactobacillus bacteremia in a 17-year-old boy with ulcerative colitis managed with systemic corticosteroids and infliximab, who presented with fever to 102°F, flushing, and chills 1 week after starting Lactobacillus rhamnosus GG probiotics. Initial blood culture on day 2 of his fever was positive for Lactobacillus, however, subsequent blood cultures on day 3 and 5 were negative VSports手机版. He was treated empirically with antibiotics for 5 days and defervesced by day 8 of his illness. 16 S rRNA sequence analysis identified the organism from the patient's blood culture and probiotic capsule as L. rhamnosus with a 99. 78% match for both the strains. This case report highlights the potential risk of Lactobacillus bacteremia in immunosuppressed patients with severe active ulcerative colitis. .