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

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.

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.

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

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

Follow-up blood culture results after treatment were negative.

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.