Body has it's own defense mechanism in this world of bacterias.Harmful bacterias are present every where so also on the whole body.They are also ingested by way of food and water intake.A drop of water may contain millions of bacteria and they have the potential to multiply very quickly.It is not that we fall prey to them in contacting infections frequently.There is a host of defense mechanisms to prevent these.
One of them is good and body friendly bacteria called lactobacillus .They are normaly present in the intestine .mouth and some other parts of body.They protect body by preventing colonisation of harmful bacterias inadverdently shallowed during taking food.They also produce some B group of vitamins required for body.They get destroyed by taking antibiotics for cure of some other infection.Normaly they recover.But many a times physicians suppliment it by providing lactabacilli from external source.
Yogurt is a good source of bacilli.
