Bacterial contamination of expressed breast milk.

In a study of breast milk collected into sterile bottles rinsed in 1% hypochlorite solution the hypochlorite solution adherent to the sides of the bottles apparently caused a large reduction in bacterial contamination of the milk after storage at 4 degrees C for up to four hours. Heating expressed breast milk at 62.5 degrees C for five minutes destroyed over 90% of the Escherichia coli, Staphylococcus aureus, and group B beta-haemolytic streptococci inoculated into the milk samples. Rinsing collecting bottles with hypochlorite solution may be valuable in collecting milk with a low bacterial content for human-milk banks. Furthermore, the currently accepted pasteurisation time of 30 minutes may be excessive.