Perianal streptococcal dermatitis imitates other common diseases in the anal region and therefore can be mistaken for "candidiasis, irritant diaper dermatitis, pinworm infestation, chronic inflammatory bowel disease, seborrheic dermatitis, or even sexual abuse." The delay in diagnosis of perianal streptococcal dermatitis can result in prolonged discomfort and additional symptoms of constipation, anal discharge or oozing, and anal fissures. Pathophysiology
Causes
In most cases of perianal streptococcal dermatitis in children, swab cultures indicate that infection is caused by the bacteria Streptococcus pyogenes, more specifically classified as group A beta-hemolytic streptococci (GAS). There have been reported cases, however, that have found perianal streptococcal cellulitis infections to be caused by group B beta-hemolytic streptococci (GBS) and, in rare cases, other groups of beta-hemolytic streptococci or Staphylococcus aureus. It is important to note, however, that in the rare adult cases of perianal streptococcal cellulitis that have been identified, the most common cause is by beta-hemolytic streptococci from group B specified as Streptococcus agalactiae. Streptococci are gram-positive bacteria that grow in chains, but they have no motility and do not generate spores. Group A streptococci and Group B streptococci are the two most common strains that are associated with pediatric cases. Infections caused by Group A streptococci are generally more mild than infections caused by Group B streptococci. The most common Group A streptococcus infections can range from strep throat to pneumonia to cellulitis. Group B streptococcus is more commonly found in the gastrointestinal and genital tracts, and can also be transmitted vertically from mother to child during vaginal labor.
These newborn cases of infection often manifest as sepsis, pneumonia, and meningitis, among other presentations.Based on cases studied of children with perianal streptococcal dermatitis, there has been a pattern of perianal infection occurring after being diagnosed with previous streptococcal infections (i.e. "strep throat"). It is believed that bacteria from these infections may be introduced to the skin of the perianal region after touching the nose or mouth and then proceeding to use the toilet or touching the area for any other reason.While perianal streptococcal dermatitis is a treatable condition, there are serious consequences that may arise if left undiagnosed and/or untreated in patients with an infection. Failure to properly diagnose and treat perianal streptococcal dermatitis may lead to more serious infections that could result in injury or death. Mechanism
Upon the initial exposure of Streptococcus pyogenes (group A beta-hemolytic streptocci) bacteria to the skin surrounding the perianal region, the bacteria adheres to the skins surface with filaments on its cell wall surface called adhesins. An adhesin found in group A beta-hemolytic streptococci of particular importance is called the M protein, which utilizes complex mechanisms to recognize various receptors on human cell types for attachment. After attachment, colonization of Streptococcus pyogenes occurs and the bacteria release many toxins that are responsible for the manifestation of symptoms of perianal cellulitis such as inflammation, fever, and itching. Secretion of hyaluronidase, also known as "spreading factor", encourages the Streptococcus pyogenes bacterium to spread more easily throughout the lower layers of skin tissue (subcutaneous tissue).