The Changes of Intestinal Normal Flora in Neonates for Seven Days Postnatally

Sung, Nam ju; Lee, Seung Gue; Kim, Me Jin; Kim, Young Ho; Yang, Seung; Hwang, Il Tae; Jung, Ji A; Lee, Hae Ran; Kim, Jae Seok

Abstract

PURPOSE
Microbial colonization of the intestine begins just after birth and development of the normal flora is a gradual process. The first bacteria colonizing the intestine in newborns are Staphylococcus, Enterobacteriaceae and Streptococcus. For several days after birth, the number of Bifidobacterium spp. increase. The aim of this study was to investigate the changes of microflora for seven days postnatally in neonatal stool.
METHODS
Fifteen neonates (breast : formula : mixed feeding 1 : 8 : 6, vaginal delivery : cesarean section 3 : 12) who were born at the Kangdong Sacred Heart Hospital, Hallym University were enrolled. First meconium and stools of postnatal 1-, 3-, and 7-day were innoculated. Blood agar plates for total aerobes, trypton bile X-glucuronide agar for E. coli, phenylethyl alcohol agar for gram positive anaerobes, MRS agar for Lactobacillus spp., bifidobacterium selective agar for Bifidobacterium spp. and cefoxitin-cycloserine-fructose agar for Clostridium difficile were used in the general incubator (CO2 free incubator), CO2 incubator or the anaerobic chamber for 48 or 72 hours at 37oC and then colony forming units were counted.
RESULTS
No microflora was identified in the first meconium. Total aerobes, E. coli, and gram positive anaerobes were significantly increased with advancing postnatal days. In only one baby, Lactobacillus acidophilus was detected 2x105 CFU/g in the seven-day stool. Bifidobacterium spp. was detected in two babies. Clostridium difficile was not detected during the seven days. There were no significant differences in the bowel flora depending on the delivery pattern and feeding method.
CONCLUSION
This study shows many changes in the intestinal normal flora in neonatal stool during seven days postnatally. If these findings are confirmed with larger studies, the data may be preliminary findings to support use of probiotics in neonates.