Does taking Amox Clav while breastfeeding affects baby microbiome?

Microbiome affected. Baby's microbiome may be affected by breastfeeding mom taking amox-clav. However amox-clav is safe to use while breastfeeding. Breastmilk is a living substance and contributes positively to baby's microbiome.
Probably. It is passed into the mothers breast milk so the baby is getting an antibiotic. Limited information indicates that serious reactions in infants are very uncommon during the use of amoxicillin-clavulanic acid during nursing, with restlessness, diarrhea and rash occurring occasionally. https://www.drugs.com/breastfeeding/amoxicillin-and-clavulanic-acid.html.