First of all I would like to inform you that the stool report is normal regarding the age of the baby.If your baby is on only breast feeding then there is no chance for infection via oral route.On the other hand your baby is gaining weight and eating well it indicates that he is going well.Actually in this age loose motion
is very common and no treatment is needed if the baby is otherwise normal.Though exclusive breast feeded baby may suffer from Lactose intolerance
but but it is very rare.You should do a stool test
for reducing substance for the diagnosis.
Finally the best thing is go to your pediatrician
for proper management