Impetigo is a bacterial infection presenting with superficial skin involvement most commonly on the face, although it may also present on other sites, such as arms and legs.
Impetigo is a bacterial infection presenting with superficial skin involvement most commonly on the face, although it may also present on other sites, such as arms and legs. Most common in young children 2 to 6 years old, the contagious nature of impetigo poses a concern in day care to other children and caregivers. Causative bacteria are Staphylococcus (at 80% frequency) followed by group A Streptococcus (in 20% to 30% of cases).
Presentation involves circular lesions, a red base, and sometimes pustules on a red base. Lesions initially fill with clear fluid, and then purulent material ruptures in a few days. Thick, honey-colored crusts soon develop over a few days. The bullous form of impetigo will have individual lesions enlarging often to 2 cm or more, which coalesce with minimal surrounding erythema. The bullae may collapse, leaving central surface erosion of various sizes with scales at the periphery. The honey-colored crust then develops.
The lesions are mildly itchy, and scratching often spreads them to other places or individuals by contact with the lesions themselves or nasal drainage. Treatment is with antibiotics—topical for most presentations and oral for more severe presentations. If colonization of the nasal passages is suspect or identified, eradication is undertaken. This disease is self-limiting, and if left untreated, it may spread and last for weeks. Rarely are systemic complications encountered. Lymphadenopathy and fever may occur with widespread areas of infection. Exclusion of methicillin-resistant Staphylococcus aureus (MRSA) is a consideration, particularly with poor response or resistance to initial therapy.
Impetigo Case Study
Sam, a 4-year-old child, presents to the clinic with his mother with a 3-day history of yellow sticky and crusty discharge on the left side of his nose and around the left side of his mouth. One week prior, Sam broke out in cold sores in the same area. Other than periodic cold sores, his medical history is unremarkable and medication allergies are denied. There is no fever, chills, or systemic symptoms, and the area of note is enlarging. Sam is not experiencing changes in affect, energy level, or gastrointestinal symptomology. He does attend day care.
What additional information would you want to know about Sam’s history and current illness? Is there diagnostic testing to consider?
Additional information to aid the diagnostic process includes any previous episodes or exposures of similar rashes and any treatments tried at home or remedies used in any previous episodes. Are there any other family members or play-group friends with similar crusty lesions?
Sam’s physical examination shows an afebrile healthy child with no lymphadenopathy. The nares show mild erythema. Isolated to the left side of the perioral region are multiple vesicles with a red moist base, a honey-colored crust, and mild scaling at the borders. Little surrounding erythema is noted, and few satellite lesions are present.
Clinical diagnosis may be made without additional testing. Because the lesions are predominately caused by Staphylococcus bacteria, consideration of MRSA may be given in lesions that Impetigo fail to respond to initial therapy or if abscesses or cellulitis develop. A culture then would be helpful. Hematology is usually not helpful as it is not affected.
What is your initial diagnosis for Sam’s presentation?
Based on Sam’s history and physical examination, nonbullous impetigo is diagnosed. If bullae had been present, bullous impetigo would have been diagnosed. Bockhart’s impetigo would have been diagnosed if lesions were present on the scalp or other hairy areas.
Treatment options should include twice-daily skin hygiene by cleansing with soap and water or antiseptic agents, which decrease the number of pathogenic bacteria on the skin. A cleansing agent like chlorhexidine is recommended for patients older than 4 years. Caregivers should also use the same washing routine to prevent cross contamination to themselves.
Topical antibiotics, such as mupirocin, are recommended as first-line treatment. Evidence shows topical antibiotics are as effective as oral antibiotics for topical disease. The course is usually 5 to 7 days, requiring application 3 times daily. Oral antibiotics are typically limited to disease of greater involvement with widespread multiple lesions. Cephalexin, erythromycin, or dicloxacillin are initial oral treatment options when MRSA is unlikely or excluded. If MRSA is suspected or confirmed, clindamycin or trimethoprim/sulfamethoxazole is suggested. Doxycycline use would be limited to patients older than 8 years.
What is your initial diagnosis for Sam’s presentation?
Use good handwashing, and avoid touching or scratching the affected area to prevent the spread of the infection to other sites and caregivers. Continue medications until the infection resolves, usually in 7 days.
In 3 weeks, Sam and his mother return. He has developed a rash that is covered by honey-colored crusted drainage on his left dorsal hand and thumb. His mother reports that he had excellent clearing of the initial rash. His mother notes he frequently “picks” his nose of dried mucus. At the physical exam, he is afebrile and appears healthy, with no bullae on the involved area. Superficial involvement is noted.
What is your new diagnosis for Sam?
Recurrent impetigo is considered suspicious of nasal colonization of the bacteria. The nasal reservoir can be a source of reinfection. In terms of treatment options, bacterial culture of Sam’s nasal passages would be considered, as well as intranasal application of mupirocin topical to both nares 3 times daily for 5 to 7 days. If other family members are affected by frequent reoccurrences of impetigo, consider topical antibiotic treatment with nasal-application prescription mupirocin. Caregivers should also be considered as a possible nasal source for reinfection, even without active symptoms. If a deep, soft-tissue infection or widespread infection should occur, Sam should be referred for parenteral therapy. The presence or absence of MRSA would dictate the antibiotics chosen.
What key educational messages would you share with Sam and his mother regarding symptomatic care of his recurrent impetigo?
Continue twice-daily skin cleansing with soap and water or antiseptic cleanser, like chlorhexidine, for Sam and his family members. He should also be brought in for follow-up if the lesions are not healing, if lesions spread or become tender, or if fever develops. Healing lesions will be dry. Application of topical antibiotics to the affected sites is needed, avoiding contamination of the ointment tube. Sam should be kept away from other children until the lesions are no longer crusty or draining. Complications from the infection could include cellulitis and, rarely, osteomyelitis, sepsis, or acute glomerulonephritis.
Impetigo is a common bacterial skin infection most likely caused by Staphylococcus or Streptococcus bacteria. Although it is often seen in children, patients of any age may develop the highly contagious infection. Minor breaks in the integrity of the skin, such as abrasions, lesions of herpes simplex, or dermatitis from contact with plants, insect bites, or insect infestations are the typical precursors.
Freeman M. Impetigo.Epocrates website. online.epocrates.com/diseases/476/Impetigo. Updated February 22, 2016. Accessed June 10, 2016.
Habif TP.Skin Disease Diagnosis and Treatment.3rd Ed. Edinburgh, Scotland: Saunders; 2011:154-159