Incidence and Outcomes of Bacteremia with Common Over-the-Counter Probiotic Organisms Among Hematopoietic Cell Transplant Recipients

Background: Probiotic supplementation has been promoted for a variety of health conditions.  Increased marketing and over-the-counter (OTC) access in pharmacies, health food stores and grocery chains has also led to increased availability of these agents.  Since safety of probiotic supplementation within the hematopoietic cell transplant (HCT) population is unknown, we sought to evaluate the incidence and outcomes of bacteremia due to organisms common to many of these OTC probiotic supplements in a population of HCT recipients. Methods: We reviewed all blood culture results from a cohort of HCT recipients transplanted at Fred Hutchinson Cancer Research Center in Seattle, WA between 2002-2011. Patients with at least one positive blood culture for common probiotic organisms (Lactobacillus species, Bifidobacterium species, or Streptococcus thermophilus) within one-year post-HCT were considered cases for this study. Patients with evidence of preexisting bacteremia from these agents (3 months prior to HCT) were excluded. Data were collected from center databases, which contain archived laboratory data, patient demographics, and clinical summaries.  Results:  A total of 18/3799 (0.47%) HCT recipients developed bacteremia with Lactobacillus species within one-year post-HCT; no events with Bifidobacterium species or S. thermophilus were identified.  Patients who developed these events had a median age of 49 years (IQR: 41, 53), and the majority were allogeneic transplant recipients (n=13, 72%). Most patients had a singular positive blood culture (n=17 [94%]); one patient developed prolonged bacteremia (30 days). Positive blood cultures for Lactobacillus species occurred at a median of 84 days post-transplant (IQR: 34, 127), with most (n=12 [67%]) occurring within the first 100-days. The overall incidence rate of Lactobacillus bacteremia was 1.54 cases per 100,000 patient-days; the highest incidence occurred during the first 100-days post-transplant (3.31 cases per 100,000 patient-days).  Incidence did not deviate significantly by year of transplant.  At the time of diagnosis, most HCT recipients were inpatient (n=12 [67%]) for a median of 37 days (IQR: 6, 78) prior to development of bacteremia.  Among outpatients (6/18 [30%]), four were admitted within 30 days after their first positive culture. Eight patients (44%) were diagnosed with acute graft-versus-host disease of the gut prior to the development of bacteremia. No Lactobacillus-attributed mortality was observed during follow-up. Conclusion: Organisms frequently incorporated in available OTC probiotic supplements are infrequent causes of bacteremia after HCT.  Studies evaluating the use of probiotics among these high-risk patients are needed.   

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Disclosures:

Nothing To Disclose

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