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Bacterial translocation in neonatal rats: the relation between intestinal flora, translocated bacteria, and influence
M Yajima1, M Nakayama, S Hatano
1Department of Nutritional Research, Nutrition Science Institute, Meiji Milk Products Co., Ltd., 1-21-3 Sakae, Higashimurayama, Tokyo 189-8530, Japan. masako_yajima@meiji-milk.com
Insights
Breast-feeding in neonatal rats significantly reduced bacterial translocation compared to formula feeding. Intestinal flora composition did not consistently predict translocated bacteria, with Staphylococcus posing a particular challenge.
Area of Science:
- Neonatal immunology
- Microbiology
- Gastroenterology
Background:
- Neonatal bacterial translocation is linked to immature host defenses and aerobic bacterial gut colonization.
- Intestinal bacterial colonization patterns vary significantly based on feeding type and infant maturity.
- Understanding these differences is crucial for preventing neonatal infections.
Purpose of the Study:
- To investigate the incidence and species of translocated bacteria in neonatal rats.
- To correlate bacterial translocation with intestinal microflora composition.
- To assess the impact of different feeding methods (breast milk vs. formula) on bacterial translocation.
Main Methods:
- Three groups of neonatal rats were studied: breast-fed (MR), formula-fed via intragastric cannula (AR), and breast-fed after cannula removal (Sham).
- Artificial rearing utilized a machine feeding system.
- Bacterial cultures from the intestine, mesenteric lymph nodes, liver, portal blood, and lungs were analyzed using a modified Mitsuoka's method.
Main Results:
- Formula-fed (AR) neonates showed significantly higher Enterobacteriaceae and Clostridium in feces compared to breast-fed (MR) neonates.
- Enterobacteriaceae, Lactobacillus, and Staphylococcus were dominant in mesenteric lymph nodes across groups.
- Systemic bacterial translocation resolved more quickly in the Sham group than in the AR group.
Conclusions:
- The composition of intestinal flora did not reliably predict bacterial species translocated to systemic sites.
- Staphylococcus species represent a potential challenge for neonatal host-defense mechanisms.
- Breast-feeding demonstrated a protective effect against systemic bacterial translocation during the suckling period in rats.
Background:
A high incidence of bacterial translocation in neonates results not only from immaturity of host-defense functions, but also from the dominant colonization of aerobic bacteria in the intestine. Bacterial colonization develops differently among breast-fed, formula-fed, premature, and full-term infants. The purpose of this study was to examine the incidence of bacterial translocation and to identify the translocated bacterial species, relating these findings to the intestinal microflora and to the type of feeding in neonatal rats.
Methods:
Animals were divided into three groups: breast-fed normal pups (MR group), formula-fed pups fed via an intragastric cannula implanted esophageally (AR group), and breast-fed pups after the removal of the cannula (Sham group). Artificial rearing was achieved using a machine feeding system. Culture and identification of the bacteria in the intestine, mesenteric lymph nodes, liver, portal blood, and lungs were made using a simplified version of Mitsuoka's method.
Results:
At 14 days of age, the dominant bacteria in the feces of the MR and Sham Groups were Enterobacteriaceae, Lactobacillus, and Enterococcus, but Enterobacteriaceae and Clostridium were significantly more common in the AR group than in the MR group. The dominant bacteria in the mesenteric lymph nodes were Enterobacteriaceae, Lactobacillus, and Staphylococcus. The extent of systemic bacterial translocation decreased earlier in the Sham group than in the AR group.
Conclusions:
The frequency with which species of bacteria were cultured from mesenteric lymph nodes and other peripheral sites did not mirror the composition of the intestinal flora. Among the translocated bacteria, Staphylococcus may be especially hard to recognize and difficult for the host-defense systems to destroy. Breast-feeding inhibited systemic bacterial translocation in the suckling period of the rat.