Objective: Little is known about bacteria on infant skin, especially during the postpartum period. Even less is known about the relationship between bacterial colonization, body location, and age. The aim of this study was to learn more about the skin’s microbiome immediately after birth and throughout the first year of life.

Design: Cross-sectional clinical study.

Setting: Routine clinical and laboratory setting in Skillman, New Jersey.

Patients/Participants: In the first cohort, 5 mothers and their neonates (healthy; full-term) were enrolled in the study. Of the mother-neonate pairs, 2 also included the father. In the second infant cohort, we enrolled 31 healthy Caucasian infants who were equally distributed between sex and age group (1-3, 4-6, and 7-12 months old). Five randomly selected mothers were also included in the study.

Methods: We took skin flora samples from infants, mothers, and fathers using an established swab technique or a cup scrub method and extracted DNA from these samples using a commercially available extraction kit. We analyzed DNA from skin samples using polymerase chain reaction (PCR), gel electrophoresis, and a bacterial tag-encoded FLX-titanium amplicon pyrosequencing approach (bTEFAP) and compared these samples to previously identified DNA markers from bacteria.

Results: Infant skin sampling revealed variations in bacterial genera by region. On the forehead, the most predominant bacterial genera were Streptococcus, Staphylococcus, and Propionibacterium while the arm contained an abundance of Streptococcus, Staphylococcus, and Corynebacterium. Large numbers of Clostridium, Streptococcus, and Ruminococcus were found on the buttocks. Bacterial diversity also varied by age. DNA analysis of infants and caregivers revealed 28 distinct gel electrophoresis banding pattern types of Propionibacterium acnes (P. acnes) isolates. Many gel banding patterns were identified in mothers and infants; 2 gel banding patterns were shared among infants, mothers, and fathers. While birth type may have influenced the microflora on arms and buttocks, birth type did not appear to affect microflora on the forehead.

Conclusion/Implications for nursing practice: Bacteria comprising the skin microbiome evolve after birth throughout the first year of life. We observed vertical transmission of bacteria from caregiver to infant, demonstrating that physical contact may play a role in the development of the microbiome. Understanding the dynamic nature of bacteria residing on infant skin may help to elucidate the requirements for maintaining normal, healthy skin as well as provide insight into the etiology and pathophysiology of eczema, cellulitis, impetigo, and other infant skin disorders.

Keywords: Neonate; skin; bacteria; microbiome; microflora