BACTERIAL TRANSLOCATION AND INTESTINAL PERMEABILITY IN PRETERM INFANTS

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1 BACTERIAL TRANSLOCATION AND INTESTINAL PERMEABILITY IN PRETERM INFANTS Dr Paul Fleming Consultant Neonatal Medicine Homerton University Hospital Honorary Research Fellow Barts and the London School of Medicine and Dentistry

2 MICROBIOME 90% of cells in the human body are bacterial, fungal, or otherwise non-human Turnbaugh PJ, et al. The human microbiome project. Nature. 2007;449:

3 GUT FLORA & VERY LOW BIRTHWEIGHT INFANTS Gastrointestinal flora in preterm infants differs significantly when compared to term counterparts Björkström MV, Hall L, Söderlund S, et al. Intestinal flora in very-low birth weight infants. Acta Paediatr. 2009;98(11): Dysbiosis refers to a disturbance in the balance of organisms in the microbiota that favours the outgrowth of potentially pathogenic constituents Maynard CL, Elson CO, Hatton RD, Weaver CT. Reciprocal interactions of the intestinal microbiota and immune system. Nature Sep 13;489(7415):231-41

4 DISEASES RESULTING FROM DYSBIOSIS Rates of death for infants weeks Gestation/1000 Live Born Infants at At that Gestation (95% CI) Time Epoch Respiratory Morbidity Infection NEC ( ) ( ) 7.35 ( ) ( ) ( ) 11.36( ) ( ) ( ) 15.3 ( ) Berrington JE, Hearn RI, Bythell M, Wright C, Embleton ND. Deaths in preterm infants: changing pathology over 2 decades. J Pediatr Jan;160(1):49-53.e1. Epub 2011 Aug 24.

5 DISEASES RESULTING FROM DYSBIOSIS Rates of death for infants weeks Gestation/1000 Live Born Infants at At that Gestation (95% CI) Time Epoch Respiratory Morbidity Infection NEC ( ) ( ) 7.35 ( ) ( ) ( ) 11.36( ) ( ) ( ) 15.3 ( ) Berrington JE, Hearn RI, Bythell M, Wright C, Embleton ND. Deaths in preterm infants: changing pathology over 2 decades. J Pediatr Jan;160(1):49-53.e1. Epub 2011 Aug 24.

6 BACTERIAL TRANSLOCATION Bacterial translocation (BT) defined as invasion of intestinal bacteria through the mucosa into normally sterile tissues Berg RD, Garlington AW. Translocation of certain indigenous bacteria from the gastrointestinal tract to the mesenteric lymph nodes and other organs in gnotobiotic mouse model. Infect Immun. 1979;23(2): Definition is extended to include bacterial toxins or antigens which damage the intestinal epithelia and enter the circulation to resulting in a systemic inflammatory response Gatt M, Reddy BS, MacFie J. Review article: bacterial translocation in the critically ill -- evidence and methods of prevention. Aliment Pharmacol Ther. 2007;25(7):

7 BACTERIAL TRANSLOCATION IN VLBW INFANTS VLBW infants are particularly risk of BT because: Dysbiosis Immature intestinal epithelium Immature immune system BT frequently cited as the entry point leading to late onset sepsis (particularly gram negative septicaemias) and in the pathogenesis of necrotising enterocolitis (NEC) Hunter CJ, Upperman JS, Ford HR, et al. Understanding the susceptibility of the premature infant to necrotizing enterocolitis (NEC) Pediatr Res. 2008;63(2): Sharma R, Tepas JJ, 3rd, Hudak ML, et al. Neonatal gut barrier and multiple organ failure: role of endotoxins and proinflammatory cytokines in sepsis and necrotizing enterocolitis. J Pediatr Surg. 2007;42(3):

8 Coordinated Neonatal Research at Homerton

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10 Intestinal Microbiota

11 Intestinal Microbiota Intestinal Epithelium

12 Intestinal Microbiota Immaturity of GI immune System Intestinal Epithelium

13 Intestinal Microbiota Immaturity of GI immune System Abnormalities in GI Blood Flow Intestinal Epithelium

14 What is the core component that makes this research work?

15 Intestinal Microbiota Immaturity of GI immune System MUCOSAL INJURY Abnormalities in GI Blood Flow Intestinal Epithelium

16 Hypothesis That bacterial translocation of the intestinal wall may occur in asymptomatic preterm infants and in some may represent an early stage of clinical sepsis and NEC

17 METHODS 1 Infants <31 weeks gestation already enrolled to the Probiotics in Preterm Babies Study (PIPS) were recruited after the first week following informed written consent Study approved by the South London REC 2 Committee (HREC 10/H0802/4 0) and funded by a Strategic Research Grant from Barts and the London Charity Blood samples were collected weekly into sterile EDTA tubes, starting at 14 days (+/- 2 days) for 4 weeks. Samples were frozen at -80 C within 4 hours of collection

18 METHODS 2 Prior to extraction, samples were pre-treated with lysozyme (50mg/ml) at 37 C for two hours and subsequently extracted using the Qiagen BioRobot EZ1 platform 16S detection was performed using a probe-based real-time PCR assay previously described by Nadkarni et al 2002 The assay was optimised using the Biorad CFX thermo-cycler and following MIQE guideline Suitable controls were included in each run Clinical outcomes for all infants were recorded

19 RESULTS 1: DEMOGRAPHICS 61 infants were recruited at Homerton University and the Royal London Hospitals between August 2010 and August 2012 Demographics: 33 male and 28 female Mean (SD) birth weight 913g (213) Median (range) gestation 26 weeks (23-30) 8 infants (13%) developed NEC ( Bells Stage II) Mean birth weight was 775G (108) Median gestation 27 weeks (25-28) Median age at onset of 26 days (range 19-72)

20 RESULTS 2: SAMPLES 213 samples were processed and 11 (5%) were positive 11 positive samples 5 positives from 5 babies who did not develop NEC 6 positives from 3 babies who developed NEC

21 RESULTS 3: SEPSIS 5 positive PCRs from 5 separate infants 3 of these babies had features of systemic sepsis within 48 hours of sampling 1 Klebsiella sepsis 1 CoNS sepsis 1 Cellulitis

22 REULTS 4: NECROTISING ENTEROCOLITIS 3 infants each had 2 positive PCRs PCR was positive one week before and just prior to the onset of clinical NEC Each of these infants had severe NEC (Bells stage 3). One infant died and the other 2 required surgery and bowel resection One positive PCR from an infant who developed NEC resulted in a mixed sequence product and the remaining samples did not sequence

23 PCR SAMPLES PRECEDING NEC Patient 1 Patient 2 Patient 3 Patient 4 Patient 5 Patient 6 Patient 7 Positive Negative NEC Patient 8 Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8

24 DISCUSSION Bacterial translocation is frequently cited in the pathogenesis of late onset sepsis and NEC in preterm babies but human studies limited Our data confirm that in some infants who develop these conditions, bacterial translocation can be demonstrated in the absence of clinical signs and precede the onset of disease

25 Thank you Acknowledgements Parents and Patients Drs N Aladangady and A Sinha Clinical and Laboratory Staff at HUH and RLH Professors Kate Costeloe, Mike Millar, Ian Sanderson and Tom MacDonald