NEONATAL SOCIETY ABSTRACTS
Analysis of faecal volatile organic compounds in preterm infants who develop necrotising enterocolitis (NEC)
Presented at the Neonatal Society 2007 Summer Meeting (programme).
Elsouad K1, Garner CE2, Probert CSJ2, Power F2, Smith S3, Ratcliffe NM3, Greenwood R4, Ewer AK1
1 Neonatal Unit, Birmingham Women’s Hospital, Birmingham UK
2 Clinical Science at South Bristol, Bristol Royal Infirmary, Bristol, UK
3 Faculty of Applied Sciences, Centre for Research in Analytical, Materials, and Sensor Sciences, University of the West of England, Bristol, UK
4 RDSU, United Bristol Healthcare Trust, Bristol Royal Infirmary, Bristol UK
Background: During gastroenteritis, an abnormal odour is sometimes noted and clinicians have reported that stool from patients with C. Difficile and cholera have characteristic smell. Investigation has shown specific changes in the volatile organic compounds (VOCs) emitted from stools during GI disease (1). We investigated the VOCs emitted from the stools of babies who developed NEC and compared them with controls.
Methods: Faeces was collected daily from infants on a neonatal intensive care unit. VOCs were concentrated by incubating the faeces then extracting the compounds from the headspace above the faeces directly onto a solid phase microextraction (SPME) fibre. The VOCs were then analysed by gas chromatography-mass spectrometry and their identity determined by library matching of the mass spectral fragmentation patterns.
Results: VOCs were examined from 6 infants (gestation range: 24+5-30+5 wks) who were subsequently diagnosed with NEC and 7 matched controls (gestations range: 24+1-30+5 wks). 19 samples were collected from the NEC infants pre-diagnosis, and 10 post-diagnosis. 36 samples from non-NEC infants were also analysed. All sample timings from this group were matched as closely as possible to the NEC infants. In the non-NEC infants the number of compounds increased with age (p=0.01 using multilevel modelling 0.486 extra compounds per day of age 95% CI 0.12, 0.86). In the NEC infants there was no apparent increase with increasing age (p=0.71, estimate of number of extra compounds per day age 0.07, 95% CI -0.27, 0.40). The statistical analysis of stool from NEC and non-NEC infants revealed the complete absence of 4 esters in all stool samples from the NEC infants; acetic acid 2-ethylhexyl ester, decanoic acid ethyl ester, dodecanoic acid ethyl ester and hexadecanoic acid ethyl ester. These compounds did occur in the non-NEC babies, although not in each of the samples.
Conclusion: This study demonstrates distinct differences in the number and composition of VOCs of the stools of babies who go on to develop NEC compared with those who do not. Although investigation of greater numbers is required it is possible that these VOCs, could be utilised as potential biomarkers in a diagnostic test for NEC prior to acute presentation.
1. Garner CE et al. Volatile organic compounds from feces and their potential for gastrointestinal disease diagnoses. FASEB J Online pub Mar 2007.