Stew, Cipro is a shitty antibiotic, and its not that strong compared to others! Stick with your penicillins and cephlosporins.
Just a little on Cipro, since it seems to be the rave now a days, it interferes with DNA replication in bacteria. Since DNA is present in both Prok and Euk cells, Cipro can also cause DNA damage in human cells, thats where you get nerve problems with Cipro use.
Penicillin acts on BACTERIAL cell wall synthesis and effects only bacteria, not human cells.
As for that infection, did he inject in the blood stream because a systemic infection after a couple days sounds very odd.