Perianal streptococcal cellulitis is a bacterial infection of the skin surrounding the anus. This condition is most often seen in children between six months and ten years of age and presents more frequently in the winter and spring months. It is caused by Group A Streptococcus, the same bacterium responsible for infections like strep throat. The infection develops in the skin’s deeper layers, known as cellulitis, distinguishing it from more superficial skin irritations.
Identifying Symptoms and Causes
The infection can occur when a child, who may have a concurrent strep throat, touches their nose or mouth and then scratches or wipes the perianal area. This autoinoculation transfers the bacteria to the skin around the anus, leading to infection.
The most prominent symptom is a distinct, bright red rash that is sharply defined, extending about two to four centimeters around the anus. This rash is often accompanied by localized pain, tenderness, and significant itching. Many children experience pain during bowel movements, which can be so uncomfortable that it leads to stool withholding and subsequent constipation.
In some cases, other symptoms may be present, such as superficial skin erosions, small cuts known as anal fissures, or a pus-like discharge from the affected area. Parents might also notice streaks of blood in the stool. While the infection is localized, a low-grade fever can sometimes develop, although widespread systemic symptoms are uncommon.
The Diagnostic Process
A healthcare provider begins the diagnostic process with a physical examination of the child. They will assess the area for the characteristic rash and ask about related symptoms like pain, itching, or changes in bowel habits. The visual presentation is a strong indicator, but a definitive diagnosis requires confirming the presence of the bacteria.
To confirm the diagnosis, the provider will perform a bacterial swab of the affected perianal skin. This procedure is quick and involves gently rubbing a sterile swab over the inflamed area to collect a sample, similar to how a throat swab is taken for strep throat.
The sample can be subjected to a rapid strep test, which can provide results quickly, often within the same office visit. For more definitive confirmation, a bacterial culture is performed, where the sample is sent to a laboratory to see if Group A Streptococcus bacteria grow from it. This culture is the gold standard for confirming the diagnosis.
Treatment and Management
The standard treatment for perianal streptococcal cellulitis is a course of oral antibiotics to eliminate the Group A Streptococcus bacteria. Penicillin and amoxicillin are commonly prescribed for this condition and are administered for about 10 days. For children who may have difficulty with the taste of certain medications, amoxicillin is often preferred as it comes in a more palatable suspension.
It is important for the child to complete the entire course of antibiotics as prescribed. Symptoms like redness and pain often begin to improve within 24 to 48 hours of starting the medication, but stopping the treatment early can lead to the infection not being fully cleared and potentially recurring. A topical antibiotic ointment, such as mupirocin, may also be prescribed to be used alongside the oral medication.
Alongside antibiotics, supportive care can help manage symptoms and discomfort. Good hygiene, including gentle cleaning of the affected area and careful handwashing, is recommended to prevent spreading the infection. To ease pain during bowel movements, a diet rich in fiber and fluids can soften stools. Sitz baths, which involve sitting in a few inches of warm water, can also help soothe itching and pain.
Differentiating from Similar Conditions
The symptoms of perianal streptococcal cellulitis can be mistaken for other common childhood conditions affecting the same area. Unlike the sharply bordered, bright red rash of a strep infection, diaper dermatitis typically appears as a more generalized redness linked to moisture and friction from a diaper.
Fungal or yeast infections, such as candidiasis, present differently. These rashes often have less defined borders and may be accompanied by satellite lesions, which are smaller spots of rash located near the main affected patch. Pinworm infections are another source of confusion, causing intense itching that is worse at night, and the small, white worms can sometimes be seen around the anus.
Constipation that leads to anal fissures can also cause pain and blood-streaked stool. A key difference is that this condition involves a visible tear or cut in the skin, rather than the widespread, uniform rash seen with perianal cellulitis.