Identification of Serratia marcescens in a mother's expressed breast milk

A 30-year-old female who underwent an emergency cesarean section reported that the breast pump tubing, infant's pacifier, and soiled diapers turned pinkish after 24 h. Serratia marcescens was isolated from the mother's breast milk, breast pump tubing, and infant's stool. This mother had no mastitis or fever symptoms but received antibiotic therapy due to endometriosis and urinary tract infection. The infant had abdominal cramps, heartburn, and frequent bowel movements; however, he was afebrile and received no antibiotics. After 3 months, this infant returned to breastfeeding as his diaper's pinkish color disappeared and the culture of the mother's breast milk was negative.