A pregnant dermatologist who frequently performs cutaneous surgery is planning to excise a large melanoma on the back of an elderly male with a history of hearing deficits and seizures. Which of the following antiseptics should the provider avoid using?

A. Isopropyl alcohol 

B. Chlorhexidine

C. Hexachlorophene

D. Povidone-iodine

 E. Chloroxylenol

Rationale: The microbial activity, onset and duration of action, risk of irritation vs allergic contact dermatitis, and toxicity are important factors to consider when selecting antiseptics for invasive skin procedures. 

Correct answer: C. Hexachlorophene

Hexachlorophene is most active against gram-positive bacteria. It is neurotoxic and can be absorbed through the skin and infants and those with repeat exposure to this product are more at risk. Hexachlorophene can be teratogenic and should be avoided in this scenario as the provider is pregnant. This medication is rarely used given that there are safer and more effective antiseptics available; hexachlorophene was previously available over the counter but its use has been heavily regulated in the United States since 1972. 

Incorrect answers: 

A. Isopropyl alcohol. Broad spectrum activity (gram-positive bacteria, gram-negative bacteria, fungi, viruses). It denatures proteins in the cell wall and does so in a very quick fashion. Downsides include flammability and being less effective than iodophores and chlorhexidine with regards to microbial coverage.

B. Chlorhexidine. Broad spectrum activity against gram-positive, gram-negative bacteria, fungi, and viruses. Chlorhexidine works by disrupting cell membranes. It has a fast onset of action and the antimicrobial effects last the longest out of answer choices. Downsides include ototoxicity (if reaching the inner ear through a tympanic membrane perforation) and corneal damage. 

D. Povidone-iodine. Broad spectrum activity (gram-positive bacteria, gram-negative bacteria, fungi, viruses and spores unlike chlorhexidine or isopropyl alcohol). It takes about 2 minutes to start working and lasts for several hours although it must remain dry to maintain its antimicrobial properties. Both allergic and irritant dermatitis can commonly occur and staining of the skin and hair can be observed. It can be used safely near the eyes and ears. 

E. Chloroxylenol is another alternative that is used less frequently than the options above as it has a slower onset of action, narrower antimicrobial coverage, and shorter duration of action than chlorhexidine. Chloroxylenol is used a surgical scrub and as a skin cleansing agent prior to catheter insertion; it does not have ototoxicity or ocular toxicity.

Additional reading at Fitzpatrick's Dermatology Chapter 202: Perioperative Considerations in Dermatologic Surgery

Bednarek RS, Nassereddin A, Ramsey ML. Skin Antiseptics. 2023 StatPearls Publishing https://www.ncbi.nlm.nih.gov/books/NBK507853/