Early Intestinal Bacterial Colonization and Necrotizing Enterocolitis in Premature Infants: The Putative Role of Clostridium

Abstract

Necrotizing enterocolitis (NEC) is among the most severe conditions that can affect preterm infants. Although the etiology of NEC remains unknown, initial bacterial colonization could play a pivotal role in the development of NEC. To further explore the putative relationship between pathogen microorganisms and NEC, we conducted a prospective casecontrol study in 12 preterm infants with a new approach based on molecular techniques. Over an inclusion period of 24 mo, 12 neonates of Ͻ34 wk gestational age admitted to the neonatal unit were enrolled. The group included three cases of NEC, and nine control infants without evidence of NEC who were matched for gestational age and birth weight. Stool samples were collected at weekly intervals from all infants. PCR and temporal temperature gradient gel electrophoresis of 16S ribosomal DNA were used to detect the establishment of bacterial communities in the digestive tract. A salient feature of the bacteriological pattern was observed only in the three infants who later developed NEC: A band corresponding to the Clostridium perfringens subgroup could be detected in early samples, before diagnosis. There was no evidence for this specific band in any of the nine controls. To our knowledge, the current report is the first to demonstrate that the use of molecular techniques based on the study of bacterial 16S rRNA genes allowed the recognition of C. perfringens species in the first 2 wk of life of three infants who later displayed symptoms of NEC. A significant temporal relationship was thus established between early colonization by Clostridium and the later development of NEC. Compared with conventional bacteriological culturing methods, the use of this new molecular approach to analyze the gastrointestinal ecosystem should therefore allow a more complete and rapid assessment of intestinal flora. Although the current data do not constitute definitive proof that the identified bacterial species was a causative agent in the development of NEC, they outline the promise of this new technique based on molecular biology, and suggest that large-scale studies on a much wider population at high risk for NEC may be warranted. (Pediatr Res 56: 366-370, 2004) Abbreviations NEC, necrotizing enterocolitis 16S rDNA, 16S ribosomal DNA TTGE, temporal temperature gradient gel electrophoresis TAE, tris-acetate/EDTA DDGE, denaturing gradient gel electrophoresis NEC is a major cause of morbidity and mortality in preterm infants. Although the etiology of NEC remains unknown, primary risk factors include intestinal immaturity, intestinal ischemia, and bacterial colonization of the intestine (1). As the gastrointestinal tract of a normal fetus is sterile, bacterial colonization must begin in the birth process and soon thereafter.Previous studies have explored the establishment of bacterial flora in term and preterm infants (2-4). Several studies noted that initial bacterial colonization could play a pivotal role in the development of NEC (5-7). Yet, classical methods using culture have not been ab...

Investigation of the early intestinal microflora in premature infants with/without necrotizing enterocolitis using two different methods

“…They found that, as compared with fecal samples from control neonates, samples from neonates who went on to develop NEC included many more kinds of bacteria that did not grow in culture. de la Cochetiere et al (23), using the molecular technique of temperature gradient gel electrophoresis, detected a band corresponding to Clostridium perfringens in three cases of neonates with NEC but in none of the controls. In our study, no specific DNA bands were correlated with the development of NEC.…”

Elective cesarean delivery affects gut maturation and delays microbial colonization but does not increase necrotizing enterocolitis in preterm pigs

“…Correspondingly, the CS preterm pigs harbored assemblages of bacteria that were lower in density and diversity than those of VD pigs. The delayed colonization, as well as the less diverse and unstable assemblages typical of CS infants, is thought to increase susceptibility to pathogen overgrowth and disease (11,47); however, how bacterial diversity affects preterm intestines highly sensitive to bacterial colonization remains poorly defined. Yet, CS alone did not increase the incidence of NEC among the preterm pigs.…”

The impact of postnatal antibiotics on the preterm intestinal microbiome

“…Although the exact association and mechanisms between neonatal intestinal microbiota and NEC remain unclear, the interplay between them appears to be a dynamic one. As early as 2004, a temporal association between early colonization with Clostridium and later development of NEC was suggested (4). This temporal relationship is again illustrated by the observation of a differing intestinal microbiome 1 wk prior to the onset of NEC (5).…”