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Infectious perianal dermatitis is in fact a group of diverse diseases that are characterised by anal and/or peri-anal inflammation in children. It may be isolated erythema that is asymptomatic or discovered due to functional anal signs such as diarrhoea, pruritus, tenesmus, stool retention, etc. In girls, the condition may be discovered due to symptoms of vulvitis; on this point it is important to remember that, due to the proximity of the anal and genital orifices to one another in young girls, genital and/or urinary signs may be evidence of an anal pathology.
Enterobius is common in children and symptomatic treatment can easily be prescribed and it is anal or perianal pruritus that is the most common clinical sign. Flubendazole is the treatment for uncomplicated intestinal forms in children.
There are various bacteria that cause perianal dermatitis in paediatric pathology:
Perianal streptococcal dermatitis affects boys more often than girls, usually around the age of five, and diagnosis can be significantly delayed. The diagnosis is made based on group A β-haemolytic streptococcus being identified from an anal swab (a sample taken from the throat is also positive in 50% of cases). Treatment consists of antibiotic therapy with oral penicillin V for at least three weeks. This does not need to be combined with a topical treatment . Bacterial investigations tend to show that staphylococci cause similar clinical pictures and that they may be involved in causing this condition more often than is generally assumed [2, 3]. Perianal dermatoses of infectious origin can also be related to the presence of Escherichia coli. The best method of identifying the bacteria responsible is by needle aspiration, but this intervention may be harmful in children. It is important, when there is perianal erythema, to take samples from the carriage sites, to look for not only group A β-haemolytic streptococcus, but other bacteria as well, so that an appropriate antibiotic can be prescribed, potentially combined with carriage site disinfection .
Recurrent perianal erythema has also been described, and this is connected to the “local” production of a staphylococcus aureus toxin. Clinically, this condition is characterised by perianal erythema that is sometimes painful; it spreads to the proximal limbs and the pelvic region, and it is accompanied by a sensation of pressure locally, erythema of the hands and feet (followed by desquamation around ten days later), pharyngitis and strawberry tongue. It develops 24 to 48 hours after acute afebrile pharyngitis. It is characterised by being recurrent but the intervals between episodes are not particularly regular (ranging from several weeks to several months) . Staphylococcus aureus secreting exfoliative toxins was isolated in the culture grown from throat swabs. This means it is crucial to look for carriage sites, so that systemic antibiotic therapy against staphylococcus can be initiated, possibly combined with carriage site disinfection.
In summary, a clinician discovering perianal erythema developing in a child must take bacterial samples from the local area, the pharynx and any carriage sites to investigate whether β-haemolytic streptococcus or staphylococcus aureus are present, so that a suitable systemic antibiotic can be chosen. Some cases of perianal streptococcal dermatitis in children may be linked to guttate psoriasis developing, as the bacterial exotoxin behaves like a “superantigen” and encourages psoriasis to develop .
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