Contamination of breast milk obtained by manual expression and breast pumps in mothers of very low birthweight infants

The objective of this study was to compare the rates of bacterial contamination of expressed breast milk (EBM) obtained by manual expression and breast pumps in mothers of very low birthweight (VLBW) infants (<1501 g). This was a randomized, controlled study carried out on 28 mothers of such babies and 92 specimens of EBM were collected: 41 specimens from 13 mothers assigned to the manual group and 51 specimens from 15 mothers in the breast-pump group. EBM was cultured quantitatively by the Miles and Misra method. Breast milk expressed by breast pumps (86.3% or 44/51 specimens) had a significantly higher rate of bacterial contamination than milk expressed by the manual method (61.0% or 25/41 specimens) (P= 0.005). When breast milk was expressed in the hospital, there was no significant difference in contamination rates between the two methods. When breast milk was expressed at home, the rates of bacterial contamination by staphylococci (P= 0.003) and Gram-negative bacilli (P= 0.002) were significantly higher in the breast-pump group than the manual group. In conclusion, the rate of bacterial contamination of EBM of mothers of VLBW infants was high, especially when EBM was obtained by the breast pump or when expression was carried out at home.