Science Technology & Engineering

* from a single donor
** can multiply at room temperature. K. pneumoniae and P. aeruginosa has cross-contaminated pasteurised milk.

• Low levels of skin bacteria are normally found in expressed milk, which is normally bacteriostatic, high levels (S. epidermidis above) are rare. The most common skin bacteria are S. epidermidis and to a lesser extent Streptococcus viridans. Some bacteria indicated above were also introduced from incompletely sterilised breast pumps (Klebsiella ssp., S. marcescens, P.aeruginosa and E. cloacae).
• Milk expressed to be used in milk banks must contain < 100,000 cfu/ml to be pasteurised or < 10,000 cfu/ml raw. Both exclude pathogens, S. aureus (coagulase-positive), group B streptococci and coliforms. No agreed-upon guidelines exist for collected or frozen milk for mother's own milk, but < 100,000 cfu/ml is frequently used. Higher levels (1,000,000 cfu/ml) of Gram-negative bacilli can be associated with sepsis.
• Some methicillin-resistant S. aureus can grow and produce enterotoxin in colostrum at 37°C.
• Four infants have died when fed milk with either Acinetobacter sp., Klebsiella sp. or coagulase-negative Staphylococcus present (>10,000 cfu/ml).
• One outbreak of F. meningosepticum was not from milk, but was located on milk bottle stoppers and 'cleaned' teats, as well as the ward environment.

Based on a table from the Proceedings of Breast Feeding, The Natural Advantage Conference. October, 1997. Sydney. Copyright J.T. May and Nursing Mothers' Association of Australia. November, 1997.