Bacterial growth in expressed mother's milk stored and transported under different simulated conditions in a tropical country

Abstract

BACKGROUND: Research on how storage and transport of expressed human milk in a tropical country affect the milk bacterial count is limited. MATERIALS AND METHODS: A cross-sectional descriptive study of 50 mothers of infants in a Sri Lankan tertiary neonatal unit was performed. Expressed mother's milk was divided into three bottles and kept under varied environmental conditions to simulate different storage and transport methods. Initial bacterial culture of milk was performed <30 minutes after expression, with further cultures at predetermined times. Bottles A and B were stored at room temperature and in a cool bag for the first 6 hours, respectively, and then refrigerated; and bottle C was refrigerated for 24 hours, transported in a cool bag for 6 hours, and rerefrigerated until 72 hours. Total colony counts >105 colony-forming units (CFU)/mL of viable microorganisms or >104 CFU/mL of either Enterobacteriaceae or Staphylococcus aureus were considered positive. RESULTS: Initial culture was positive in 30% (15/50) of samples; majority, 87% (13/15), of these were S. aureus. For bottle A, 26% (13/50), 36% (18/50), 34% (17/50), and 26% (13/50) of samples were positive at 4, 6, 24, and 72 hours, respectively. For bottle B, positive cultures were found in 26% (13/50) and 17% (8/47) of samples at 24 and 72 hours, respectively. For bottle C, results were similar to bottle B. CONCLUSIONS: Transportation of expressed mother's milk for 4 hours in a tropical climate using a low-cost cool bag, with refrigeration at other times, maintained acceptable bacterial counts for up to 72 hours after expression. Hygienic practices at collection are extremely important as most samples with significant bacterial growth were positive on initial culture. KEYWORDS: expressed breast milk; expressed mother's milk; storage; transport; tropical country.