Perianal cellulitis, also known as perianitis or perianal streptococcal dermatitis, is a bacterial infection affecting the lower layers of the skin (cellulitis) around the anus. It presents as bright redness in the skin and can be accompanied by pain, difficulty defecating, itching, and bleeding. This disease is considered a complicated skin and soft tissue infection (cSSTI) because of the involvement of the deeper soft tissues.Perianal cellulitis is most commonly caused by group A beta-hemolytic streptococcus bacteria (Streptococcus pyogenes), which resides normally ("in small numbers") in the human throat and on the human skin. Other less common causes may include infection with group B beta-hemolytic streptococci (Streptococcus agalactiae), a bacteria found in the human vagina of some, or Staphylococcus aureus, a common component of the bacterial community in the human nose and/or skin.Perianal cellulitis occurs mainly in male children between six months and 10 years of age, however, there are documented cases of perianal cellulitis in adults as well. Oral antibiotics are the first line treatment for perianal cellulitis and may be used in combination with topical antibiotics. Since the infection occurs within the deeper layers of skin, using a topical treatment by itself may not be effective. In about 20% of cases, recurrence of perianal streptococcal dermatitis infection occurs within 3.5 months. Routine hygiene practices should also be encouraged in children and adults in order to reduce the risk of recurrent infection. Signs and symptoms
Perianal cellulitis manifests as multiple symptoms that are inconsistent with a systemic disease.
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.