Your theory is based on a fallacy. When someone (possibly, and not all patients) has transient tingling in their extremities, it does not mean that the drug is WORKING -- it just means that the drug is in their body.

The tingling is a possible side effect, in some but not all people. It is not correlated to the drug killing bacteria. If it were so correlated, people would be having tingling wherever the bacteria was active, not just in fingers and toes.