Penicillin can be used to treat pelvic inflammatory disease, but its antibacterial spectrum is narrower. It is mainly used to treat Gram-positive cocci and positive bacilli, such as Streptococcus haemolyticus, Staphylococcus aureus or gonococcus, etc. These bacterial infections of pelvic inflammatory disease are more effective with penicillin. If anaerobic bacterial infection is considered in pelvic inflammatory disease, it is best to add Ornidazole or Metronidazole for simultaneous treatment. If there is Chlamydia trachomatis infection, azithromycin can be added and the combination of antibiotics will only be more effective. Be sure to do a drug sensitivity test before using penicillin, because this drug is prone to allergic reactions.