Bacteria into bloodstream caused by oral probiotics based on whole genome sequencing: A case report.

Rationale: Bacillus licheniformis and Lactiplantibacillus plantarum are facultative anaerobes and gram-positive bacteria. They are commonly included in probiotic preparations and are administered orally in clinical practice to promote a balanced gut microbiota.

Patient concerns: An 85-year-old man with irritable bowel syndrome and reflux esophagitis underwent distal pancreatectomy and was administered oral probiotics. Blood culture was positive for B. licheniformis and L. plantarum. We conducted whole-genome sequencing for homology analysis and pathogenicity prediction of the strains isolated from the patient's blood culture and oral probiotics.

Diagnosis: The initial diagnosis was bacterial entry into the bloodstream resulting from the consumption of B. licheniformis and L. plantarum probiotic preparations.

Interventions: The patient was treated with discontinuation of oral probiotics and timely administration of antibiotics.

Outcomes: Follow-up blood culture results after treatment were negative.

Lessons: Probiotics are generally considered relatively safe but should be preceded by risk screening in vulnerable populations. Whole-genome sequencing revealed the potential risks of probiotic use through homology analysis and prediction of virulence factors and antibiotic resistance.