Differences in the Microbiological Profile of Raw and Pasteurized Breastmilk from Hospital and Community-Based Donors at the First Human Milk Bank in Vietnam

Background: Microbiological quality is one of the key safety standards in human milk bank (HMB) operations. We describe the profiles of bacteria in donor human milk (DHM) before and after the pasteurization of samples collected from breastfeeding women in the hospital and from the community in the first HMB in Vietnam. Methods: Data were collected between February 2017 and January 2022 from an online HMB monitoring system. First, DHM samples were cultured, and the number of colony-forming units (CFU) were counted before (n = 708) and after pasteurization (n = 1146). The gram-staining method combined with the Vitek 2 Compact system were used to identify types of organisms at the Da Nang Hospital for Women and Children's Laboratory. Passing criteria for DHM included pre-pasteurization samples had a total colony count <10(5) CFU/mL and post-pasteurization was <10 CFU/mL. Results: During five years of operation, Da Nang HMB had 491 donors (48.7% were hospital and the rest community donors) who donated an average amount of 14.2 L over 45 days. Of this DHM volume, 84.9% of donor samples passed the pre- and post-pasteurization microbiological tests. DHM from community donors had a higher pass rate (87.8%) compared to that from hospital donors (79.5%). Before pasteurization, 15.4% of DHM samples had a bacteria count <10(3) CFU/mL, 63.0% had 10(3)-<10(5) CFU/mL, and 21.6% had >= 10(5) CFU/mL. Most of the unpasteurized DHM samples (93.0%) had microorganism growth: with one organism (16.4%), two (33.9%), three or more (43.6%). After pasteurization, 17.9% samples had a bacteria count of 1-9 CFU/mL and 7.2% had >= 10 CFU/mL. DHM samples from community donors had a lower bacterial count and number of organisms than those from hospital donors both before and after pasteurization. The highest microorganisms from unpasteurized DHM samples were Staphylococcus epidermidis (74.2%), Acinetobacter sp. (52.1%), gram-positive bacillus (51.7%), Staphylococcus coagulase-negative (15.8%), and Staphylococcus aureus (10.5%). Common microorganisms from pasteurized DHM were gram-positive bacillus (21.0%), Staphylococcus epidermidis (3.9%), and Acinetobacter sp. (0.9%). Samples from the hospital tended to have a higher contamination with those microorganisms than those from community donors. Conclusions: The majority of DHM samples in Da Nang passed microbiological testing criteria. DHM from community donors had higher pass rates than hospital donors. Corrective actions are needed to improve HMB operations and hospital microbiological quality standards, as well as general improvements in water and sanitation.

Automated summary

This study analyzed the bacteria profiles in donor human milk (DHM) before and after pasteurization in the first human milk bank (HMB) in Vietnam. The results showed that DHM from community donors had higher pass rates compared to those from hospital donors. However, samples from hospital donors had higher contamination with common microorganisms. Therefore, corrective actions are needed to improve HMB operations and hospital microbiological quality standards, as well as general improvements in water and sanitation.