Conference Coverage

Anti-infective update addresses SSSI choices



– What’s new in infectious disease therapeutics for dermatologists? More topical choices, antiparasitics, and some “big guns” to target skin and skin structure infections, according to Justin Finch, MD. He ran through an array of updates at the Orlando Dermatology Aesthetic and Clinical Conference.

Dr. Justin Finch of the University of Connecticut, Farmington. Kari Oakes/MDedge News

Dr. Justin Finch

While naturally occurring smallpox was globally eradicated in 1980, small research stores are held in the United States and Russia, and effective antivirals are part of a strategy to combat bioweapons. Tecovirimat (TPOXX) is an antiviral that inhibits a major envelope protein that poxviruses need to produce extracellular virus. Approved by the Food and Drug Administration in mid-2018, it is currently the only antiviral for treating variola virus infection approved in the United States, noted Dr. Finch of the University of Connecticut, Farmington. He added that 2 million doses are currently held in the U.S. Strategic National Stockpile.

Another anti-infective agent that won’t be used by those practicing in the United States, but which promises to alleviate a significant source of suffering in the developing world, is moxidectin. The anthelmintic had previously been approved for veterinary uses, but in June 2018, the FDA approved moxidectin to treat onchocerciasis, also known as river blindness. The drug defeats the parasitic worm by binding to glutamate-gated chloride ion channels; it is licensed by the nonprofit Medicines Development for Global Health.

Another antiparasitic drug, benznidazole, was approved to treat children aged 2-12 years with Chagas disease in 2017, Dr. Finch said.

Also in 2017, a topical quinolone, ozenoxacin (Xepi) was approved to treat impetigo in adults and children aged at least 2 months. Formulated as a 1% cream, ozenoxacin is applied twice daily for 5 days. In clinical trials, ozenoxacin was shown to be noninferior to retapamulin, he said.

A new topical choice is important as mupirocin resistance climbs, Dr. Finch added. A recent Greek study showed that 20% (437) of 2,137 staph infections studied were mupirocin resistant. Of the 20%, all but one were skin and skin structure infections (SSSIs), with 88% of these being impetigo.

In the United States, mupirocin resistance has been seen in one in three outpatients in a Florida study and in 31% of patients in a New York City sample. Other studies have shown mupirocin resistance in Staphylococcus aureus isolates with resistance in the 10%-15% range among children with SSSIs, Dr. Finch said.

Two other new antibiotics to fight SSSIs can each be administered orally or intravenously. One, omadacycline (Nuzyra), is a novel tetracycline that maintains efficacy against bacteria that express tetracycline resistance through efflux and ribosomal protection. Approved in late 2018 for acute bacterial SSSIs, omadacycline treats not just methicillin-sensitive and methicillin-resistant S. aureus, but also Streptococcus species and gram-negative rods such as Enterobacter and Klebsiella pneumoniae, Dr. Finch noted.

Another new fluorinated quinolone, approved in 2017, delafloxacin (Baxdela) has broad spectrum activity against gram-negative and gram-positive bacteria.

Dr. Finch reported that he has no relevant conflicts of interest.

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