New study from the U.S.:
Title: Bacterial Content of Fortified and Unfortified Holder Pasteurized Donor Human Milk during Prolonged Refrigerated Storage
In: Journal of Pediatric Gastroenterology and Nutrition 2019 June 20. Authors: Mandru C, Perrin MT, Iyer R, Liveris D, Schwartz I, Alpan G1, Parvez B.
Results: "96.5% of milk samples manipulated in a vertical laminar flow hood were negative for bacterial growth. In the remainder 3.5% of the samples the maximum growth was 1 colony forming unit/ 0.1 ml plated. Higher colony counts were observed when the laminar hood was not used. In all cases, the colonies represented common skin bacteria and demonstrated an inconsistent and unsustained growth. Fortifier status and storage time were not significantly associated with increased bacterial growth (P > 0.05).”
Conclusions: "Unfortified and fortified Holder pasteurized donor human milk remain largely free of bacterial growth for up to 96 hours of refrigerated storage in NICU settings. Sample handling techniques are important for preventing microbial contamination." Abstract only: https://www.ncbi.nlm.nih.gov/pubmed/31232828