Influences of antibiotics on biodiversity of intestinal microbiota in newborns

Introduction
The neonatal period is crucial for intestinal colonization. It is assumed that
the gastrointestinal tract of newborns becomes colonized immediately after
birth with organisms from mainly the mother, the role of the environment is
unknown. Maternal vaginal and fecal flora provides the natural first source of
colonising organisms for the neonatal gut. After this first inoculation the
flora changes rapidly, presumably under the influence of diet. Some authors
have suggested that the composition of the first human microbiota could have
long lasting effects, up to months (Grönlund 1999) or even years (Salminen
2004).
The composition of enteric microbiota in early days of life seems therefore an
important factor for achieving good health in later life.

Antibiotics and micro flora
A particularly potent means of disturbing early-colonisation patterns is by
using antibiotics with a broad and unselective spectrum in the postnatal period
and in the first days of life. Antibiotics are very commonly used when a
neonatal sepsis is suspected without considering their impact on gut
microbiota. Most studies of normal microbiota have been done in volunteers or
in patients undergoing decontamination of procedures for intestinal surgery.
These have reported a decrease in anaerobes, aerobes, and gram negative bacilli
and an increase in yeast and E.coli after the administration of antibiotics to
adults (McFarland 2000). Less is known of the impact of antibiotics on the gut
flora of the newborn infant and the long term effects.

Immune system
There is evidence that intestinal bacteria play an important role in the
postnatal development of the immune system (Heavey 1999, Björksten 2001).
Alterations in the development of the intestinal microbiota might increase
atopic disease and early wheezing (Isolauri 2008, Alm 2008). Murine studies
have also demonstrated that changed early-life gut flora may promote the
development of autoimmunity in genetically predisposed animals (Bach 2002).

Human milk
Human milk is a factor in the initiation and development of neonatal gut
microbiota, not only because it contains prebiotic substances that promote the
growth of selected bacterial groups in the infant gut (Boehm 2005), but also
because this substrate represents a continuous source of micro-organisms to the
infant gut during several weeks after birth (Martín 2003, Heikkilä 2003). The
presence of a few predominant bacterial species in breast milk (Martin 2007)
may explain why gut microbiota of breast-fed infants is composed of a narrow
spectrum of species, and a more diverse microbiota develops only after weaning.

Route of delivery
Route of delivery is a major confounder for the intestinal microbiota
development (Biasucci 2008). The studies about the route of delivery could not
be corrected for antibiotic usage of the mothers.

It is unclear at this stage what the effects of antenatal and/or postnatal
antibiotics are on the short and long term colonization with intestinal
microbiota. And if this is influenced by the micro flora and breast milk of the
mother.

1.) Is the gut flora of the healthy infant on day 3, day 7 and day 28
originally from the mother or the environment?
2.) Is the process of colonizing in healthy term infants dependent on the mode
of delivery?
3.) Does breast milk contain bacteria and are the equal to the flora of the
mother or the infant?
4.) Does the administration of antenatal antibiotic influence the colonization
of the infant?
5.) Does the administration of postnatal antibiotic influence the colonization
of the infant?

- Non-therapeutic observational study in Groningen, The Netherlands and
Jakarta, Indonesia.
- Only term infants (37-42 wks).
- Mother and infant will be included in one of the five groups. Five groups
will be formed based on route of delivery, prescription of antenatal
antibiotics and prescription on postnatal antibiotics. For more information see
the flowchart and the inclusion criteria.


For all groups:
- Stool of the infants will be collected on three different moments:
1.) 3 days after birth
2.) 7 days after birth
3.) 28 days after birth
- Stool of the mothers will be collected within 3 days after birth.


For group 1 and group 5 only:
- Breast milk of the mothers will be collected on day 1 (< 24hrs), day 3, day 7
and day 28.

None