Abstract & Commentary

Absence of pathogens in intestinal tissue of patients with necrotizing enterocolitis

By Dean L. Winslow, MD, FACP, FIDSA, Chief, Division of AIDS Medicine, Santa Clara Valley, Medical Center; Clinical Professor, Stanford University School of Medicine, is Associate Editor for Infectious Disease Alert.

Dr. Winslow is a speaker for Cubist Pharmaceuticals and GSK, and is a consultant for Siemens Diagnostic.

Synopsis: 28 surgical specimens from patients with necrotizing enterocolitis (NEC) were examined using multiplex real-time polymerase chain reaction (RT-PCR) to detect gastrointestinal pathogens. Infectious enteritis pathogens were not detected in any specimens.

Source: Ullrich T, et al. Absence of gastrointestinal pathogens in ileum tissue resected for necrotizing enterocolitis. Ped Infect Dis J 2012; epub ahead of print.

Fresh ileum tissue specimens from infants with NEC or non-NEC diagnoses were provided by the Pathology departments at the children's hospitals at Vanderbilt and at University of Illinois. Standard methods of nucleic acid extraction were employed. Multiplex RT-PCR was used to detect 15 bacterial and viral pathogens (including Salmonella, Shigella, Campylobacter, C. difficile toxin A/B, ETEC, E.coli O157, STEC E. coli, V.cholerae, Yersinia, Giardia, Entamoeba histolytica, Cryptosporidium, Adenovirus 40/41, Rotavirus, and Norovirus). 23 ileum samples from 22 cases of NEC, 14 samples from non-NEC controls, 1 tissue sample from a child with confirmed Giardia enteritis, and one stool specimen from a child with Norovirus infection were examined. Median gestational age of NEC patients was 28.2 weeks and all samples were collected between 2007 and 2011. All of the NEC and non-NEC tissue specimens were negative for gastrointestinal pathogens included in the multiplex assay. The two positive controls were strongly positive for Giardia and Norovirus respectively.

Commentary:

NEC is a severe and poorly understood complication of prematurity characterized by a generally irreversible inflammatory process leading to bowel necrosis. It occurs in 7% of infants less than 1,500 grams at birth and is associated with significant morbidity and mortality with most patients requiring surgical resection of variable amounts of small bowel. Anecdotal reports and small case series have suggested etiological roles for a variety of gastrointestinal pathogens including C. difficile, C. perfringens, E. coli, adenovirus and other enteric viruses. Formula feeding has also been implicated by association in many case series.

This study, which utilized a sensitive and specific multiplex RT-PCR technique, is an important advance in our understanding of this disease, and may reduce the use of unnecessary and potential harmful antibiotics in the NICU, which are often given empirically for treatment of NEC. While the multiplex PCR method used in this study ruled out the presence of the specific pathogens examined, it may still be of use to repeat this study using broad-spectrum 16S rDNA PCR primers to look for potentially unidentified potential pathogens. However, the present study along with the lack of histopathological evidence of bacterial pathogens in resected specimens suggests that infectious agents are not generally causal in NEC.