A tale of caution: prolonged Bacillus clausii bacteraemia after probiotic use in an immunocompetent child

Introduction. Bacillus clausii as a probiotic supplement is increasingly used in both adult and paediatric patient populations. There is limited awareness about potential adverse effects. Case presentation. We report a case of prolonged (111 days) B. clausii bacteraemia after brief probiotic use in a 17-month-old immunocompetent child, without a definite focus of infection and in the absence of predisposing risk factors or underlying co-morbidities. We identified seven probiotic use-associated cases of prolonged B. clausii bacteraemia (mean duration [range] 64 days [14–93 days] where data were available) in the literature, all with underlying co-morbidities. Conclusion. B. clausii probiotic preparations may cause prolonged bacteraemia, rendering patients with underlying co-morbidities as well as those with unrecognized risk factors vulnerable for significant infectious complications.