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TOPLINE:

In a 10-year analysis of multi-strain probiotic formulation (MPF) use in preterm infants, bacteraemia with probiotic organisms occurred in only 0.6% of cases (12 out of 2109 exposed infants), with no deaths directly attributed to the infection.

METHODOLOGY:

• In this single-centre retrospective study conducted in Montreal, Canada, MPF was administered to infants at < 33 weeks' gestational age or with a birth weight < 1500 g, starting at 0.5 g daily with the first enteral feed until 34 weeks' postmenstrual age.
• Researchers examined 2109 infants who received probiotics containing five bacterial strains: Bifidobacterium longum subspecies longum, B longum subspecies infantis, B breve, B bifidum, and Lactobacillus rhamnosus.
• Data from the microbiology laboratory database from 2001 to 2022 were used to identify patients with positive blood cultures for bacterial species present in the MPF.

TAKEAWAY:

• MPFs were used since more than 10 years, with bacteraemia occurring in 12 (0.6%) cases; nine of these were due to Bifidobacterium species and three were due to Lactobacillus rhamnosus. No cases were reported before MPF use.
• Among the affected infants, eight had gastrointestinal complications concurrent with bacteraemia and five required urgent abdominal intervention.
• Concomitant infections were observed in five cases, including bacteraemia with other pathogens, suspected urinary tract infections, and fungaemia.
• Two out of eight critically ill infants died after intensive care withdrawal, but their deaths were not attributed to bacteraemia.

IN PRACTICE:

"In our cohort, bacteraemia with organisms contained in MPF was uncommon, and there were no cases of mortality directly attributed to bacteraemia in preterm infants exposed to MPF. Given the variety of probiotics formulations used in practice, further studies are needed to monitor actively their safety," the authors wrote.

SOURCE:

The study was led by Assil Abda, CHU Sainte-Justine, Montreal, Quebec, Canada. It was published online on February 19, 2025, in The Journal of Pediatrics.

LIMITATIONS:

The retrospective design and absence of contemporary controls limited any causal inference. Changes in blood culture systems over time may have influenced detection rates. The study lacked local quality control of probiotic formulations through whole-genome sequencing, preventing confirmation of genetic relatedness between blood culture isolates and probiotic strains. Due to small blood volumes in premature infants, anaerobic blood cultures were not routinely performed, potentially underestimating the incidence of bacteraemia caused by anaerobic bacteria.

DISCLOSURES:

The study received no external funding. The authors reported no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.