Microorganisms in Expressed Breast Milk Stored at Room Temperature: Comparison of Standard Cleaning Versus UV Sterilization of Breast Pumps

Abstract

Introduction: Storing expressed breast milk (EBM) at tropical room temperatures (~31°C) accelerates bacterial proliferation. This study aimed to compare the efficacy of standard cleaning (soap and water) versus ultraviolet (UV) sterilization of breast pumps in minimizing the presence of potentially pathogenic organisms (defined as isolated Gram-negative bacilli and Staphylococcus aureus) in EBM stored at 31°C for 3 hours.

Methods: This prospective paired comparative study enrolled 30 breastfeeding mothers in Makassar, Indonesia. Each participant provided two EBM samples using her personal breast pump under two sequential preparation methods: standard cleaning (soap and water) and UV sterilization. Samples were stored at 31°C and cultured at 0 and 3 hours. The categorical presence of potential pathogens and quantitative bacterial loads (log10 CFU/mL) were analyzed using the McNemar exact test and the Wilcoxon signed-rank test, respectively.

Results: After 3 hours of storage, EBM from the standard cleaning group demonstrated a significantly higher prevalence of potentially pathogenic organisms compared to the UV sterilization group (63.3% vs. 43.3%, p = 0.031). Quantitatively, the UV sterilization method resulted in a significantly lower median bacterial load (4.93 log10 CFU/mL) compared to standard cleaning (6.00 log10 CFU/mL) (p < 0.001). The predominant potential pathogens isolated were Acinetobacter baumannii and Klebsiella pneumoniae.

Conclusion: UV sterilization of breast pump equipment was significantly more effective than standard cleaning in reducing the initial microbial load transferred to EBM. This method decreased both the quantitative burden and the frequency of pathogens, highlighting its utility in mitigating contamination risks in tropical settings.