Expressed milk and nipple yeast infection

Should I throw out milk that I expressed before treatment for nipple yeast infection?

Throwing out milk that was collected when a mother had a nipple yeast infection is unnecessary as giving this milk will not increase the risk of another infection.

A) Reasons that expressed milk can be safely given to the baby

Do not throw out milk that you expressed before starting treatment for a nipple yeast infection. It is perfectly good to use.  

1) Candida may already be present in the baby's mouth

It may be normal for you to have Candida, the organism that causes nipple yeast infection, on your areolas, in your baby’s mouth and gut, and even in your breast milk (Hallen-Adams 2017; Moossavi 2020). Between 20% and 80% of mothers without symptoms have been shown to have Candida present in their breast milk (Boix-Amorós 2017; Mutschlechner 2016).

Giving the baby milk with a little bit of Candida will make no difference to the baby or mother. If the mother has had a nipple yeast infection, the baby would have already been exposed to Candida and it is likely already present in the baby’s mouth. It is unlikely to increase the risk of nipple yeast infection or thrush in the baby.

2) Candida does not grow well in breast milk

Furthermore, Candida does not grow well in breast milk and is therefore unlikely to cause infection of the baby's mouth. 

References

Boix-Amorós A, Martinez-Costa C, Querol A, et al. Multiple Approaches Detect the Presence of Fungi in Human Breastmilk Samples from Healthy Mothers. Sci Rep. 2017 Oct 12;7(1):13016
 
Hallen-Adams HE, Suhr MJ. Fungi in the healthy human gastrointestinal tract. Virulence. 2017 Apr 3;8(3):352-358

Moossavi S, Fehr K, Derakhshani H, et al. Human milk fungi: environmental determinants and inter-kingdom associations with milk bacteria in the CHILD Cohort Study. BMC Microbiol. 2020 Jun 5;20(1):146   

Mutschlechner W, Karall D, Hartmann C, et al. Mammary candidiasis: molecular-based detection of Candida species in human milk samples. Eur J Clin Microbiol Infect Dis. 2016 Aug;35(8):1309-13