Comparison of two methods for cleaning breast pump milk collection kits in human milk banks

SUMMARY

Background

Appropriate decontamination of breast pump milk collection kits (BPKs) is critical to obtain safe milk for infants and to avoid discarding donor human milk (DHM).

Aim

To evaluate two strategies for BPK decontamination by assessing microbial cultures and the proportion of discarded DHM, according to the criteria of the National Institute for Health and Care Excellence for pre-pasteurization cultures.

Methods

Prospective comparative study, allocation ratio 1:1, microbiologist-blind.

Participants

47 new donors in a human milk bank in Madrid.

Interventions

Study group (N=21): BPKs washed with water and detergent after each use and further steam decontamination within a microwavable bag. Control group (N=26): washing, rinsing and drying only. Five samples: first sample by hand expression and four samples (one per week) collected using the same pump and method.

Outcomes

Primary: proportion of DHM discarded due to contamination. Secondary: comparison of the microbiota between samples obtained by hand expression and breast pump in both groups.

Findings

In total, 217 milk samples were collected: 47 by hand expression and 170 by pump expression (78 from study group). Steam decontamination of BPKs using a microwavable bag after washing resulted in a lower proportion of discarded DHM samples (1.3% vs 18.5%, P<0.001) and samples contaminated with Enterobacteriaceae (1.3% vs 22.8%, P<0.001) and Candida spp. (1.3% vs 14.1%, P<0.05) compared with samples collected with BPKs that were washed but not steam decontaminated. There were no differences in bacterial contamination between samples obtained using steam decontaminated BPKs and those obtained by hand expression.

Conclusions

Steam decontamination of BPKs using a microwavable bag after washing decreases the amount of discarded DHM and the number of samples with potentially pathogenic bacteria.

Introduction

The use of breast pumps is very common in neonatal intensive care units and human milk banks. However, breast pumps may be a potential route for the transmission of infectious diseases. As such, breast pump milk collection kits (BPKs) should be cleaned carefully before each use [1], [2], [3]. Most human milk banks include a pre-pasteurization milk culture in their methods. If donor human milk (DHM) is highly contaminated, it is discarded. The National Institute for Health and Care Excellence (NICE) guidelines recommend discarding milk if the pre-pasteurization sample has a total microbial count exceeding 10⁵ colony-forming units (cfu)/mL, or 10⁴ cfu/mL for Enterobacteriaceae or Staphylococcus aureus [4].

Therefore, it is essential for BPKs to be decontaminated appropriately. Benefits and drawbacks of each decontamination method have been published [5]. However, there is a lack of scientific evidence to determine which method is most effective. Most guidelines recommend washing with detergent followed by thorough rinsing and drying after each use [2], [6], [7]. The US Centers for Disease Control and Prevention (CDC) has recently issued updated guidelines following an unfortunate case of a preterm infant who suffered from meningitis by Cronobacter sakazakii, transmitted from expressed breast milk (EBM) obtained with a contaminated breast pump [3]. CDC now recommends using an additional decontamination method, particularly for highly susceptible infants such as premature babies, children under 3 months of age or those with immunodeficiency [7].

In order to collect relevant information, which may allow the establishment of evidence-based recommendations, and to facilitate the expression process for donors as much as possible, a prospective comparative study was conducted in human milk donors. The objective was to evaluate two different BPK cleaning strategies (washing, rinsing and drying vs washing and steam decontamination) according to the results of milk microbial cultures and the proportion of discarded DHM. DHM was discarded according to the criteria defined in the NICE guideline for pre-pasteurization cultures.