Dermatology

Perianal Streptococcal Disease (perianal streptococcal cellulitis or dermatitis, perineal streptococcal dermatitis, perianal bacterial dermatitis)

Perianal streptococcal disease [perianal streptococcal cellulitis or dermatitis, perineal streptococcal dermatitis, perianal bacterial dermatitis

Are You Confident of the Diagnosis?

Perianal streptococcal disease (PSD) is a localized cutaneous infection caused by group A ß-hemolytic Streptococcus. Key characteristics on history and physical examination should alert the practitioner to this entity. The rash is typically very bright pink-red and often waxes and wanes in severity and is associated with localized pruritus. PSD is usually confined to the immediate perianal area, although involvement of the perineum, genitalia, intertriginous creases and even the axillae is well described. Concomitant vulvovaginal or penile group A streptococcal infection has been collectively termed perineal streptococcal disease.

What you should be alert for in the history

The typical presentation of PSD is a complaint of perianal itching. Patients may also describe rectal tenderness, pain with defecation, blood-streaked stools, constipation, abdominal pain, and/or irritability. Girls with vulvovaginal involvement may note pruritus and tenderness of this area as well as dysuria and vaginal discharge. Some studies have documented concomitant or recent streptococcal pharyngitis, although half of patients may not complain of a sore throat. Fever is rarely associated.

Characteristic findings on physical examination

On physical examination, perianal erythema is the classic appearance of PSD. This erythema varies in severity from mild and pink to, more often, bright or “beefy” red (Figure 1). It will often have a distinct margin and may be accompanied by other signs of inflammation such as superficial edema, tenderness, or infiltrate. Occasionally, the patient may also have multiple anal fissures and bleeding. The literature has also reported the rare finding of a papular rash on buttocks or scarlatiniform rash over the lower abdomen. Clinical pharyngitis, defined as erythema with or without exudate, may be noted.

Figure 1.

Perianal streptococcal disease affecting inguinal folds and penis.

Expected results of diagnostic studies

Definitive diagnosis of PSD is made by the growth of a pure culture of group A Streptococcus from a perianal swab. Culture material may be adequately collected by rolling or stroking a dry swab over the affected skin. The practitioner should specifically ask the laboratory to test for group A ß-hemolytic streptococci because some laboratories will not adequately search for this organism by culturing on blood agar plates in the evaluation of routine perineal swabs. For faster results a rapid strep test can be employed. Invasive tests, such as culture by needle aspiration or blood tests for anti-streptolysin O antibodies, anti-streptokinase, or anti-streptodornase B titers, are not warranted.

Several case reports note symptom persistence often for many months, until appropriate diagnosis and effective treatment are instituted. Unfortunately, the correct diagnosis of PSD is often delayed likely due to a lack of awareness of PSD in the medical community. A bacterial culture for Streptococcus should be done in any refractory cases of perianal erythema in order to differentiate it from other diagnoses.

Diagnosis confirmation

The differential diagnosis of PSD in children includes oxyuriasis (pinworm infestation), candidiasis, allergic contact dermatitis, irritant contact dermatitis, atopic dermatitis, psoriasis, lichen sclerosus et atrophicus or seborrheic dermatitis. Staphylococcal perianal dermatitis has also been reported. Disorders of the gastrointestinal system, such as constipation or inflammatory bowel disease should be considered. Signs of perianal erythema and fissures have sometimes been seen as indicators of possible sexual abuse.

Who is at Risk for Developing this Disease?

PSD was first described in 1966; since then, it has been reported around the world. The exact incidence of PSD is not known. A recent study, from a US general pediatric practice, detected PSD in one per 300 patients seen.

PSD may occur in adults, but it typically affects prepubertal children from infancy, with a peak incidence between the ages of 3 and 5 years. Interestingly, the age distribution of PSD mirrors streptococcal impetigo, but differs from streptococcal pharyngitis, which is seen predominately in children ages 5 to 15 years. Adult cases have been reported but are rare. Boys appear to be affected more than girls. There is a peak occurrence in the late winter / early spring months (March, April, and May).

What is the Cause of the Disease?

Etiology

Pathophysiology

Many hypotheses are offered in the literature to explain the transmission of group A ß-hemolytic streptococci to perineal tissues, but none have been proven. Spread between siblings and other children within homes, daycares, and schools has been documented and is theorized to be due to digital-oral-fecal spread, airborne dissemination, or shared fomites on toilet seats, towels, or bathwater. The association of pharyngeal streptococcal infection with perianal infection, by reported concomitant cases and PSD’s seasonal distribution, supports the theories of autoinoculation or gastrointestinal spread from an infected nasopharynx, but some investigators have offered evidence against these suggested routes.

The vast majority of PSD cases are credited to group A ß-hemolytic streptococcal infection; although, a few reports identify other causative bacteria, including group B ß-hemolytic streptococci, group G ß-hemolytic streptococci, non-group A ß-hemolytic streptococci, and S.aureus.

Systemic Implications and Complications

The natural course of untreated PSD is unknown, but delays in treatment are suspected to result in prolonged discomfort and to local tissue spread to the genitalia, which may cause vulvovaginitis or balanitis. Prolonged PSD is also thought to contribute to toilet avoidance, constipation, and/or fecal incontinence.

Many studies have found concomitant pharyngeal colonization with or without clinical pharyngitis, but it is unclear whether PSD precedes or follows pharyngeal colonization. Post-streptococcal complications have been reported with PSD, including post-streptococcal glomerulonephritis and guttate psoriasis.

Treatment Options

Systemic

Oral penicillin V

Children < or = 27 kg: 250mg 2-3 times/day for 10 days

Children >27 kg, adolescents, and adults: 500mg 2-3 times/day for 10 days

Amoxicillin

Children 3-18 years: 50mg/kg once daily (maximum dose: 1000mg) for 10 days

Children =12 years: Extended release tablets: 775mg once daily for 10 days

Amoxicillin/clavulanic acid

Cefuroxime

Alternatives to penicillin-allergic patients

Clindamycin

Erythromycin

Roxithromycin

Azithromycin

Clarithromycin

Topical (in conjunction with systemic antibiotic)

Antiseptic -chlorhexidine clioquinol

Antibiotic – mupirocin, retapamulin, erythromycin, bacitracin, fusidic acid

Optimal Therapeutic Approach for this Disease

Oral penicillin V is the most recognized therapy of choice for PSD because of its wide availability and cost effectiveness. Alternatives in cases of penicillin allergy are erythromycin, azithromycin, or clarithromycin. Some studies have suggested roles for oral amoxicillin, amoxicillin/clavulanic acid, clindamycin, and cefuroxime.

The majority of authors feel that a traditional 10-day course of systemic antibiotic is sufficient; however, others suggest a longer treatment duration of 14-21 days. Consider longer treatment in patients with refractory disease.

The effectiveness of topical treatment alone is uncertain. Some studies advocate the use of topical therapy in conjunction with oral antibiotics, such as the addition of antiseptic (eg, chlorhexidine clioquinol) or antibiotic (eg, mupirocin, retapamulin, fusidic acid, erythromycin, bacitracin) ointments.

Even with appropriate antibiotic coverage, treatment failures and recurrences are common.

Patient Management

The medical practitioner should have a high index of suspicion for PSD. External anal examination and gentle perianal swabbing should be performed whenever a child presents with clinical features suggestive of this infection. Patients should be encouraged to complete the full course of treatment to reduce the risk of recurrence as well as therapy resistance. Since treatment failures and recurrences are common, careful patient follow up is necessary.

Have parents monitor for darkening of urine, periorbital swelling, and/ or general malaise, as these are common signs of poststreptococcal glomerulonephritis.

Unusual Clinical Scenarios to Consider in Patient Management

Occasionally, untreated PSD may trigger acute guttate psoriasis in susceptible individuals. Poststreptococcal glomerulonephritis has been documented as a rare complication. No cases of rheumatic fever or pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) have been reported in association with PSD.

What is the Evidence?

Moglielnicki, NP, Schwartzman, JD, Elliott, JA. "Perineal group A streptococcal disease in a pediatric practice". Pediatrics. vol. 106. 2000. pp. 276-81.

(This is an office based, year-long case series of 23 pediatric patients with culture confirmed perineal streptococcal infection. It confirms average age (5 years) and late winter/ spring time peak occurrence.)

Heath, C, Desai, N, Silverberg, NB. "Recent microbiological shifts in perianal bacterial dermatitis: Staphylococcus aureus predominance". Pediatr Dermatol. vol. 26. 2009 Nov-Dec. pp. 696-700.

(This report highlights the varying bacterial species that can cause perineal dermatitis.)

Orden, B, Martin, R, Franco, A, Ibañez, G, Mendez, E. "Balanitis caused by group A beta-hemolytic streptococci". Pediatr Infect Dis J. vol. 15. 1996 Oct. pp. 920-1.

(A review of streptococcal balanitis and its clinical presentations.)

Neri, I, Bardazzi, F, Marzaduri, S, Patrizi, A. "Perianal streptococcal dermatitis in adults". Br J Dermatol. vol. 135. 1996 Nov. pp. 796-8.

(Although very uncommon, perianal streptococcal disease can occur in adults. This series of four patients details their clinical course and management.)

Stermer, E, Sukhotnic, I, Shaoul, R. "Pruritus ani: an approach to an itching condition". J Pediatr Gastroenterol Nutr. vol. 48. 2009 May. pp. 513-6.

(A good review of the differential diagnosis of perianal itching in both children and adults.)

Amren, DP, Anderson, AS, Wannameker, LW. "Perianal cellulitis associated with group A streptococci". AM J Dis Child. vol. 112. 1966. pp. 546-52.

(The original description of perianal infections caused by group A Streptococcus.)
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