VANCOUVER – Here’s a key message to bear in mind in the current era of methicillin-resistant Staphylococcus aureus: “Don’t forget streptococci,” Dr. Dirk M. Elston urged at the World Congress of Dermatology.
“Cellulitis is usually not staphylococcal, it’s streptococcal. Erysipelas, of course, is also streptococcal. And almost all impetigo probably begins as a streptococcal infection, even though the staphylococci outnumber the streptococci over time,” said Dr. Elston, managing director of the Ackerman Academy of Dermatopathology in New York.
The reason this message is important is because sulfa drugs are unreliable for the treatment of streptococcal infections.
“There is no indication for the treatment of active streptococcal disease with sulfa drugs,” the dermatologist said.
He cited a retrospective case-control study of 2,096 children with undrained, noncultured skin and soft tissue infections treated empirically on an outpatient basis with beta-lactams, clindamycin, or trimethoprim-sulfamethoxazole as monotherapy. The treatment failure rate was significantly higher in patients receiving trimethoprim-sulfamethoxazole. Clindamycin and beta-lactams were equally effective as first-line empiric therapy (Pediatrics 2009;123:e959-66).
Clindamycin has the added advantage of providing a two for one benefit: It’s effective against both MRSA and strep, Dr. Elston noted.
Necrotizing fasciitis is increasing in prevalence, and in a recent case series from Belfast, the most commonly isolated causative organism obtained from debrided tissue cultures was group A Streptococcus. The investigators found the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) scoring system lacked diagnostic sensitivity; however, an elevated serum lactate at presentation had 90% diagnostic sensitivity and provided added value as a prognostic indicator (J. Plast. Reconstr. Aesthet. Surg. 2015;68:304-11).
“Necrotizing fasciitis often begins as a minor skin infection. Any patient with pain out of proportion to the clinical appearance or just the opposite – they look horrible and yet it’s relatively nontender – those are both potentially true medical emergencies,” Dr. Elston said.
It’s important to understand that streptococcal virulence is not a static phenomenon, he added.
“We’ve seen changes in strep virulence periodically. You’ll have waves of much more toxic strep. There was a wave a number of years ago in Missouri where there was a very high death rate among 19- and 20-year-olds. Right now Australia is seeing an epidemic of severe streptococcal disease, with sepsis and toxic shock,” according to the dermatologist.
Many of these Northern Australian cases begin with pyoderma, and many of those pyodermas occurred secondary to scabies (Trop. Med. Int. Health 2015;20:40-7).
Dr. Elston reported receiving research support from more than a dozen pharmaceutical companies and serving as a consultant to half a dozen.