The colonization of the preterm intestine could have been speculated to be very homogeneous since the neonates were at the same hospital unit (environment) even though Palmer et al., [17] showed that the composition and temporal patterns of the microbial communities in stool samples from term babies

varied widely from baby to baby for their first year of life. However the composition of the intestinal microbiota in healthy pre- or term neonates present in the small intestine is not yet known due to the lack of samples [17, 18, 24, 25]. Previous studies based on culture techniques have focused on single organisms as predisposing for NEC [7, SBE-��-CD order 26, 27]. Clostridium spp. and especially C. perfringens due to the fermentation of carbonhydrate substrates to hydrogen gas has been suspected [3, 6, 9]. Very few neonates were colonised with Clostridium spp. in this study but there was a significant correlation between a positive signal from the probes for Clostridium spp and pneumatosis intestinalis as verified by histopathology. It was specified that this Clostridium colonization was due to C. butyricum and C. parputrificum. A previous study has shown that these two lactose fermenting clostridium species can induce cecal NEC-like lesions in a gnotobiotic quail model and these lesions may be linked to short-chain fatty acid production

[28]. There was no correlation with pneumatosis intestinalis found by X-ray and Clostridium spp. LY411575 mouse and maybe pneumatosis intestinalis

described on X-ray is different from the pneumatosis intestinalis described on tissue surgically removed. It seems therefore like C. butyricum and C. parputrificum are responsible for pneumatosis intestinalis when verified by histopathology, but because of the low frequency of Clostridium spp in our samples we believe that the pneumatosis intestinalis is a secondary effect Oxalosuccinic acid of NEC and that these Clostridia are not the primary pathogens of NEC. Ralstonia and Propionibacteria were detected in most of the specimens where laser capture microdissection was used. Ralstonia spp. is a new genus including former members of Burkholderia spp. (Burkholderia picketti and Burkholderia solanacearum). Burkholderia spp. has been described in children suffering of NEC [29] and Ralstonia picketti has been reported to be a persistent Gram-negative nosocomial infectious organism [30]. R. picketti can cause harmful infections and is mainly considered as an opportunistic pathogen of little clinical significance but R. pickettii isolates have been reported to be resistant or had decreased susceptibility to aminopenicillins, ureidopenicillins, restricted-spectrum cephalosporins, ceftazidime, and aztreonam [31]. The major conditions associated with R.