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High Genetic Diversity Among Bacillus cereus Isolates Contaminating Donated Milk at a Canadian Human Milk Bank Gene, Mathew; Guthrie, Jennifer L.; Li, Kevin; Teatero, Sarah; Paterson, Aimee; Li, Angel; Doyen, Alain; Yamamura, Deborah; Khan, Sarah; Srigley, Jocelyn A.; Stone, Debbie; O’Connor, Deborah L.; Poutanen, Susan; Unger, Sharon; McGeer, Allison; Fittipaldi, Nahuel

Abstract

Bacillus cereus poses a persistent challenge for human milk banks (HMBs) due to its ability to survive Holder pasteurization (HoP; 62.5 °C for 30 min). To ensure neonatal safety, any milk found to be contaminated post-HoP must be discarded, which impacts milk supply and adds to the operational demands of HMBs. In this study, we analyzed 688 B. cereus isolates from human milk (pre- and post-HoP), as well as from patient and environmental sources, to investigate human milk contamination by B. cereus at a Canadian HMB. Despite the limited temporal and geographic scope of the collection, the isolates exhibited remarkable genomic diversity, comparable to global B. cereus collections. Phylogenetic analysis at the core genome level revealed no clear clustering by isolate source, suggesting multifactorial pathways of B. cereus contamination. Isolates surviving HoP displayed gene variants linked to sporulation and cell wall integrity, suggesting a potential basis for HoP tolerance. Our findings emphasize that while genomic analyses offer major valuable insights, they alone are insufficient to address the complexities of B. cereus contamination in HMBs. Addressing this challenge will require combining genomic tools with robust monitoring systems, improved human milk-handling protocols, and pasteurization strategies better-suited to countering B. cereus resilience.

Item Metadata

Title
High Genetic Diversity Among Bacillus cereus Isolates Contaminating Donated Milk at a Canadian Human Milk Bank
Creator
Gene, Mathew; Guthrie, Jennifer L.; Li, Kevin; Teatero, Sarah; Paterson, Aimee; Li, Angel; Doyen, Alain; Yamamura, Deborah; Khan, Sarah; Srigley, Jocelyn A.; Stone, Debbie; O’Connor, Deborah L.; Poutanen, Susan; Unger, Sharon; McGeer, Allison; Fittipaldi, Nahuel
Contributor
Children's Hospital (Vancouver, B.C.). Research Institute; Children's Hospital (Vancouver, B.C.)
Publisher
Multidisciplinary Digital Publishing Institute
Date Issued
2025-05-15
Description
Bacillus cereus poses a persistent challenge for human milk banks (HMBs) due to its ability to survive Holder pasteurization (HoP; 62.5 °C for 30 min). To ensure neonatal safety, any milk found to be contaminated post-HoP must be discarded, which impacts milk supply and adds to the operational demands of HMBs. In this study, we analyzed 688 B. cereus isolates from human milk (pre- and post-HoP), as well as from patient and environmental sources, to investigate human milk contamination by B. cereus at a Canadian HMB. Despite the limited temporal and geographic scope of the collection, the isolates exhibited remarkable genomic diversity, comparable to global B. cereus collections. Phylogenetic analysis at the core genome level revealed no clear clustering by isolate source, suggesting multifactorial pathways of B. cereus contamination. Isolates surviving HoP displayed gene variants linked to sporulation and cell wall integrity, suggesting a potential basis for HoP tolerance. Our findings emphasize that while genomic analyses offer major valuable insights, they alone are insufficient to address the complexities of B. cereus contamination in HMBs. Addressing this challenge will require combining genomic tools with robust monitoring systems, improved human milk-handling protocols, and pasteurization strategies better-suited to countering B. cereus resilience.
Subject
Bacillus cereus; human milk bank and hospital; human milk; holder pasteurization; contamination routes; genetic diversity; whole-genome sequencing; sporulation; neonatal health
Genre
Article
Type
Text
Language
eng
Date Available
2025-06-02
Provider
Vancouver : University of British Columbia Library
Rights
CC BY 4.0
DOI
10.14288/1.0449007
URI
http://hdl.handle.net/2429/91248
Affiliation
Medicine, Faculty of; Non UBC; Obstetrics and Gynaecology, Department of; Pathology and Laboratory Medicine, Department of
Citation
Microorganisms 13 (5): 1136 (2025)
Publisher DOI
10.3390/microorganisms13051136
Peer Review Status
Reviewed
Scholarly Level
Faculty; Researcher; Other
Rights URI
https://creativecommons.org/licenses/by/4.0/
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CC BY 4.0