Table 1 Criteria for participant inclusion and exclusion

· people aged ≥65 years and admitted to hospital

Inclusion criteria

· exposed to one or more antibiotics within the last 7 days or are about to start antibiotic treatment

· consultant approval to invite patient to join the study

· diarrhoea present¹

· immunocompromise²

· severe illness requiring high dependency or intensive care³

· prosthetic heart valve

· C. difficile in past 3 months

Exclusion criteria

· active inflammatory bowel disease⁴

· suspected acute pancreatitis⁵

· known compromised gut blood supply⁶

· jejunal tube in situ or receiving jejunal feeds

· previous adverse reaction to probiotics

· unwilling to discontinue exiting use of probiotics