Antibiotics skin testing for Infants 6 mos. below

I'm having orientation on my new job as a staff nurse. One of the policies is that infants 6mos below don't get skin testing for antibiotics and when asked for the reason, our batch failed to give any rationale. Our chief nurse was disappointed and asked it be our assignment to know the answer by tomorrow.

I have worked in MS and never encountered any policies like that before. I tried googling to no avail. I'm clueless but I know that at that age infants have enough immune response to warrant a skin test. Please help.

Thanks.