Bifidobacterium Bloodstream Infection in a Lymphoma Patient Undergoing Chemotherapy: A Case Study and Implications for Probiotic Use.

BACKGROUND Fermenting bacilli producing lactic acid, including Bifidobacterium spp., are supposed to have low pathogenicity and no virulence for humans. Probiotics consisting of those fermenting bacilli can prevent and treat symptomatic gastrointestinal conditions, such as diarrhea. We use probiotics even in cancer patients, those who are immunocompromised, because a preferable effect to the intestinal commensal microbiome has been shown in a recent report. Some case reports warn of a rare risk of bloodstream infection caused by probiotics. However, complete prohibition of probiotic use in cancer patients abandons the benefits. CASE REPORT A 75-year-old Japanese woman with malignant lymphoma was treated with immune-chemotherapy regimen consisting of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP). The patient had onset of febrile neutropenia during chemotherapy and had Bifidobacterium breve bloodstream infection on day 8 after the eighth R-CHOP treatment. She had usually eaten commercial yogurt every morning. This yogurt was produced from only Lactobacillus bulgaricus and Streptococcus thermophilus. It did not contain Bifidobacterium breve. The bloodstream infection in this case looked like it derived from her food; however, it was not associated with her habitual foods. The patient was treated with meropenem for 8 days and experienced complete remission of the bloodstream infection. CONCLUSIONS We speculate that fermenting bacilli can also be a source of bloodstream infection, not necessarily associated with probiotic strains, in cancer patients treated with chemotherapy. Additionally, we recommend that probiotics can alleviate alimentary tract symptoms in immunocompromised patients.