This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Microbiology Pa-2 and Pa-3 (Sterilization and Bacterial Genetics), Subject name: Microbiology
Which of the following used as skin antiseptic? 
Select and explain. 
A. Cidex, B. Cresol, C. Chlorhexidine, D. Lysol
C: Chlorhexidine
Answer: C: Chlorhexidine 
Explanation: Option 1 Glutaraldehyde is less toxic, less irritant and less corrosive, hence is best used to sterilize endoscopes and cystoscopes: It is used as 2% concentration (2% cidex) for 20 min. Option 2, 4 Phenolics as disinfectants: Cresol, xylenol, Lysol and oho-phenylphenol are used as disinfectants in laboratories and hospitals. All have the ability to retain activity in presence of organic matter. They are toxic and irritant to skin, hence used as disinfectants but not as antiseptics. Option 3 Skin antiseptics are Halogens: Povidone iodine-Betadine (best) and Tincture iodine. Phenol as antiseptics: Chlorhexidine (Savlon), Chloroxylenol (Dettol). Alcohol: Isopropyl alcohol, Ethanol. Heavy Metal salts: Silver sulfadiazine (burns surfaces), 1% Silver nitrate (Ophthalmia neonatorum) Surface active agents: Cationic detergents, Anionic surfactant (common soaps).u Dyes: Aniline and Acridine.