Frequently misdiagnosed, streptococcal intertrigo more commonly affects infants and toddlers but is rarely reported, especially compared with other Streptococcus pyogenes infections, including impetigo, erysipelas, and cellulitis.1
Intertrigo, meaning “between” (inter) and “to rub” (terere) in Latin, describes any skin disorder involving two opposing skin surfaces that touch or rub to cause friction.2 The continuous chaffing, coupled with moisture trapped within the skin folds, leads to irritation and maceration, which provides an ideal environment for pathogens to thrive. Thus, frictional dermatitides that arise may become secondarily infected with one or more microorganisms, such as Candida albicans, Staphylococcus aureus, Streptococcus pyogenes, and even organisms less commonly associated with cutaneous infection, such as Proteus mirabilis.3
Streptococcal intertrigo may affect any intertriginous area, but most commonly it affects the folds of the neck; this is likely because of the combination of the deep folds that develop in shorter, infantile necks and the moisture from drool and saliva that pools in the area.5,6 In addition to these cervical folds, other intertriginous areas commonly are affected, including the inguinal, axillary, popliteal, posterior auricular, perianal, and genital folds.
Perianal streptococcal disease may present in a similar manner as streptococcal intertrigo, manifesting as well-demarcated, beefy red plaques in the skin folds around the anus and, in females, frequently perivaginally.7 Unlike streptococcal intertrigo, perianal streptococcal disease is often characterized by pain, pruritus, and fissuring of the involved area.8 It is associated with pharyngeal colonization of group A beta-hemolytic streptococci.7
Diagnosis is straight forward and may be confirmed by a positive streptococcal rapid antigen test of swab specimens of one or more surfaces of affected skin or by culture from a skin swab yielding growth of the organism.1,5 Skin biopsy is not necessary. If the index of suspicion for candida is high, a potassium hydroxide preparation and culture may be performed. Checking serum anti-DNase B antibodies, antistreptolysin O, and pharyngeal cultures is often unrevealing.9 A urinalysis may be performed to assess for poststreptococcal glomerulonephritis if the patient later develops facial or orbital edema, hypertension, hematuria, or lethargy.9
Treatment consists of systemic antistreptococcal therapy; oral amoxicillin and penicillin frequently have been used.9 Moisture in the area should be reduced with application of absorptive powders and physical barriers, such as zinc oxide, after gentle cleansing of the area.5
Other diagnoses to consider when evaluating dermatitides affecting skin folds include: other infectious causes, which may be ruled out by fungal or bacterial culture; inverse psoriasis, which will frequently demonstrate scale; atopic dermatitis, which will be pruritic with history of atopy; irritant or contact dermatitis, which will often have correlating clinical history; seborrheic dermatitis, which will often involve greasiness and scale; and less commonly, acrodermatitis enteropathica, which will be accompanied by diarrhea and hair loss.2,9 Scabies also may be on the differential if the patient endorses severe pruritus with close contacts with similar symptoms.
Ms. Han is a medical student at the University of California, San Diego. Dr. Eichenfield is chief of pediatric and adolescent dermatology at Rady Children’s Hospital–San Diego. He is vice chair of the department of dermatology and a professor of dermatology and pediatrics at the university. They had no conflicts of interest or disclosures to report.
4. BMJ Case Rep. 2018 Mar 20.