Intestinal Permeability and Bacterial Translocation in Preterm Infants

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

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;449:804-10.

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):1762–1767
• 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. 2012 Sep
13;489(7415):231-41

DISEASES RESULTING FROM DYSBIOSIS
Rates of death for infants 24-31 weeks Gestation/1000 Live Born
Infants at At that Gestation (95% CI)
Time Epoch Respiratory Morbidity Infection NEC
1988-1994 127 (115-139) 13.52 (9.62-17.43) 7.35 (4.47-10.23)
1995-2001 104 (91.8-116) 10.65 (6.84-14.46) 11.36(7.43-15.29)
2001-2008 65.7 (55.99-75.41) 13.44 (9.04-17.87) 15.3 (10.61-19.97)
Berrington JE, Hearn RI, Bythell M, Wright C, Embleton ND. Deaths in
preterm infants: changing pathology over 2 decades. J Pediatr. 2012
Jan;160(1):49-53.e1. Epub 2011 Aug 24.

DISEASES RESULTING FROM DYSBIOSIS
Rates of death for infants 24-31 weeks Gestation/1000 Live Born
Infants at At that Gestation (95% CI)
Time Epoch Respiratory Morbidity Infection NEC
1988-1994 127 (115-139) 13.52 (9.62-17.43) 7.35 (4.47-10.23)
1995-2001 104 (91.8-116) 10.65 (6.84-14.46) 11.36(7.43-15.29)
2001-2008 65.7 (55.99-75.41) 13.44 (9.04-17.87) 15.3 (10.61-19.97)
Berrington JE, Hearn RI, Bythell M, Wright C, Embleton ND. Deaths in
preterm infants: changing pathology over 2 decades. J Pediatr. 2012
Jan;160(1):49-53.e1. Epub 2011 Aug 24.

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):403–411
• 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):741–757

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):117–123
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):454–461

Coordinated Neonatal Research at
Homerton

Intestinal
Microbiota

Intestinal
Microbiota
Intestinal
Epithelium

Intestinal
Microbiota
Immaturity of
GI immune
System
Intestinal
Epithelium

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

What is the core component that makes
this research work

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

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

METHODS 1
• Infants

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

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)

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

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

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

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

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

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