No. Thrush is an infection caused by a fungus (sometimes called yeast) this type of infection is common in babies because their immune system is still developing. Fungal infections are common in warm moist areas like the mouth, diaper area (especially the creases) and folds of skin such as under the neck. It is not related to type of formula. Antibiotic use can increase yeast infections.
No. Thrush, is a very common yeast infection of the mouth, seen mostly in the first year of life, and very infrequently after that. Oral antibiotics not only kill the bacteria they are prescribed for, but also normal bacteria on the skin and in the mouth. This disturbs the normal balance of bacteria and yeast, and the yeast seize their opportunity, move in and the result is thrush.