It doesnt necessarily kill all bacteria on contact (that would make it bactericidal), but it prevents them from reproducing
Yes, BPC-157 can often be used alongside antibiotics, but it should be done under medical supervision
Hemoglobin 42:189193 Neumar RW, Otto CW, Link MS, Kronick SL, Shuster M, Callaway CW, Kudenchuk PJ, Ornato JP, McNally B, Silvers SM, Passman RS, White RD, Hess EP, Tang W, Davis D, Sinz E, Morrison LJ (2010) Part 8: adult advanced cardiovascular life support: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care
doi: 10.3389/fimmu.2018.01689
What changes is the chemistry at the ends of the peptide, and those changes affect how long the molecule survives in the body, how much of it actually gets where its going, and (theoretically) what dose you need to use