Gut-Derived Bone Infection in the Neonatal Rat

Abstract

The risk of osteomyelitis is increased in the premature and critically ill neonate. Although potential sites of bacterial entry are present in many of these infants, the source of infection frequently cannot be established. This study was performed to assess the possible role of bacterial translocation from the intestine in the origin of bone infection using models of breast-fed and formula-fed rat pups. Newborn Sprague-Dawley rats suckled either ad libitum by the dam (n ϭ 30), or were fed a rat milk-simulated formula (n ϭ 30). After 3 d, the animals were killed, and the left femur, heart blood, mesenteric lymph nodes, liver, spleen, and terminal ileum were excised. Organs were analyzed for bacteria by standard microbiologic procedures. Bacterial translocation occurred in 23% of breast-fed rats; the bone was not infected in any of these animals. After feeding of formula diet, bacterial counts of the ileum were markedly elevated (p Ͻ 0.001), and the composition of the gut flora was disrupted. Bacterial translocation was noted in all formula-fed rats. Bone cultures were positive in 23 of 30 (77%) rats after formula-feeding (p Ͻ 0.001 versus breast-feeding). Organisms translocated to the bone included Enterococci, Proteus, Enterobacter, and Escherichia coli. Bacterial species cultured from the bone correlated with the individual colonization pattern of other extraintestinal organs and with the composition of the ileal flora. Members of the gut flora can escape the intestine and colonize the bone in formula-fed rats. The gut should be considered as a potential source for osteomyelitis in the neonate. Acute osteomyelitis in the neonate is a leading cause of destruction of the physis resulting in high rates of permanent handicaps (1-3). Because the major route of infection is via the bloodstream, opportunities for organisms to gain access to the circulation may favor the development of osteomyelitis. Premature and sick neonates represent the high-risk group, and in this population potential sites of bacterial entrance are frequently present. Many of these infants undergo vascular manipulation including insertion of central catheters for total parenteral nutrition or invasive monitoring, which have long been linked to the development of skeletal infection. In most cases, however, the origin of bacterial entry remains unknown (4). Therefore, alternative routes of infection should be considered.Among the organisms causing neonatal osteomyelitis, Staphylococcus aureus is most common, followed by group B streptococci and Gram-negative bacteria (1, 5-7). All of these organisms have the ability to colonize the neonatal gut. They may represent normal luminal residents, or members of an abnormal microflora, as frequently seen in hospitalized neonates (8). It is now widely accepted that organisms can escape from the gastrointestinal tract and invade extraintestinal organs, a process termed as bacterial translocation (9, 10). In normal adult individuals, translocation of bacteria from the gastrointestinal tract is limited by a n...

Bacterial Translocation of Coagulase-Negative Staphylococci in Rats following Intestinal Ischemia-Reperfusion Injury

“…10 5 CFU/ml, even transient intestinal ischemia (30 min) caused significant bacterial translocation in the rat model. Although our findings in rats cannot be directly applied to the situation in infants, several observations are consistent with the hypothesis that skeletal infection of the neonate may be caused by translocation of bacteria from the gut [12]. This finding is also of important clinical significance since CoNS has been recognized as a common cause of serious infections such as sepsis, pneumonia Based on results from the present study, translocation of CoNS from gut to portal blood stream following IRI may be a key event in the pathogenesis of bacteremia in IRI rats.…”

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Factors affecting breastfeeding adherence among Chinese mothers

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