Bacterial Growth in Human Milk During Continuous Feeding

ABSTRACT

The present study was undertaken to determine both the time at which exponential growth of bacteria ensued in human milk during a continuous feeding and whether the fat content of the milk changed during a continuous feeding. Breast milk samples were obtained from 19 healthy lactating women between the 7th and 28th postpartum day. Nine samples were refrigerated and utilized in a simulated continuous feeding within 24 hours of collection. The remaining 10 samples were frozen for four to six weeks until use in the simulated feeding study. Bacterial colony counts and fat content (by creamatocrit) were then measured at the beginning of the simulated feeding and at hourly intervals from five to eight hours after the initiation of the study. Results indicated that logarithmic growth of the contaminating bacteria was not observed during the study time. No significant increase in total colony count was observed over the course of study in the frozen milk samples, whereas a significantly increased colony count was apparent by six hours for the fresh milk samples. Fat content of the milk decreased significantly within six hours for the frozen samples and within eight hours for the fresh milk. These data would suggest that when continuous drip feeding methods are employed for providing human milk to newborn infants, it may be desirable to change the entire feeding apparatus (syringe, tubing, and milk) at four hour intervals in order to optimize caloric intake and minimize the risk of bacterial overgrowth.