Antibacteria herbs versus antibiotics

Hi all,

Do they both kill bacteria, the good and the bad, therefore are harmful for the flora? Why the herbs such as pau d'arco and chaparrel that we take to try to kill a bunch of bateria and virus are not considered as harmful to the flora? Or may be they are. Then when we take this herbs, should we also need to take prebiotics and probiotics? I am a little confused on this issue, please, enlighten me.

Thank you,

LongNhi