Biguanides - pharmacology, Disposable Equipment, Biguanides - administration & dosage, Humans, Disinfection, Herniorrhaphy, Surgical Equipment, Thyroidectomy, Preoperative Care, Klebsiella - isolation & purification, Surgical Wound Infection - prevention & control, Enterococcus faecalis - isolation & purification, Anti-Infective Agents, Local - administratio...