Re: How do humans first recieve E. coli in their intestine?

When a baby mammal is born their intestines are sterile.  Upon the moment 
of their first breath microorganisms began to inhabit many locations.  
Escherichia coli can find its way to the intestine of a newborn through 
oral ingestion.  If the baby is fed infant formula it is possible that 
some low levels of non disease causing E. coli could be ingested via the 
formula, water used to re-hydrate the formula, unclean bottle, unclean or 
contaminated teething ring, transfer of E. coli from other people or 
animals to the hands or fingers of the infant and then subsequent 
ingestion of the organisms by the infant sucking on their fingers and 
lastly possibly from the nipple of the mother during breast feeding if it 
is not clean.  However, it is not inappropriate for the infant to ingest 
non-disease causing forms of E. coli or other bacteria.  Proper digestion 
is dependant upon the infant building a “normal intestinal flora” of 
which E. coli is but one member.  It is however, important to make sure 
that when touching a new born or handling items that the newborn might 
put into their mouth that ones hands are clean and recently washed.