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Colonization of intestinal bacteria in the normal neonate: comparison between mouth and rectal swabs and small and
J M Van Camp1, R Drongowski, R Gorman
1Section of Pediatric Surgery, C.S. Mott Children's Hospital, Ann Arbor, MI 48109.
Insights
Young rabbit pups under six days old often have sterile intestines, despite positive bacterial growth from mouth and rectal swabs. This finding impacts understanding neonatal sepsis and bacterial translocation in infant rabbits.
Area of Science:
- Microbiology
- Neonatal Physiology
- Animal Models
Background:
- Neonatal sepsis is a significant concern in vulnerable populations.
- Understanding the developing microbiome is crucial for preventing infections.
- Bacterial translocation in young animals requires further investigation.
Purpose of the Study:
- To investigate the gastrointestinal microbiome development in young New Zealand white rabbits.
- To determine the relationship between age and bacterial colonization in rabbit intestines.
- To assess the implications for neonatal sepsis and bacterial translocation.
Main Methods:
- Seventy-four rabbit pups aged 2 to 13 days were studied.
- Mouth swabs, rectal swabs, small bowel, and large bowel specimens were collected.
- Specimens were incubated and plated under aerobic and anaerobic conditions.
Main Results:
- Nearly all mouth and rectal swabs showed bacterial growth.
- Small and large bowel bacterial growth significantly increased with rabbit age.
- Young rabbits (under 6 days) frequently had sterile intestines despite positive swabs.
Conclusions:
- Young rabbit pups possess a developing microbiome, with sterile intestines being common in the first week of life.
- This sterility may explain the low incidence of spontaneous bacterial translocation in very young rabbits.
- Findings have implications for neonatal sepsis prophylaxis and treatment strategies.
Abstract:
Seventy-four New Zealand white rabbit pups were divided into four groups: group I, 2 days of age (n = 9); group II, 3 to 5 days of age (n = 24); group III, 6 to 8 days of age (n = 27); and group IV, 10 to 13 days of age (n = 14). Mouth swabs (MS), rectal swabs (RS), small bowel specimens (SB), and large bowel specimens (LB) were obtained from each rabbit, incubated for 24 hours in thioglycolate broth, and plated on blood agar in aerobic and anaerobic environments. After 24 hours, growth on blood agar plates were observed. All MS specimens and all but one RS specimen showed positive growth. Growth of both LB and SB specimens increased significantly with age (P < .04). In addition, SB growth was significantly less than RS or MS growth in groups I, II, and III (P < .05). LB growth was significantly less than RS or MS growth in group I (P < .01) and tended to be less in groups II and III (62.5% v 100% and 93% v 100%, respectively). These data show that nearly half of normal rabbits under 6 days of age have sterile small and large intestines despite almost 100% growth from rectal and mouth swabs. These findings partially explain the absence of spontaneous bacterial translocation in young rabbit pups (under 4 days of age) and have important implications for the prophylaxis and treatment of neonatal sepsis.