Impetigo
Impetigo
Disease History, Characteristics, and Transmission
Introduction
Impetigo is a skin disorder characterized by crusting lesions and commonly occurs among children at an early school age. Infection is due to either Staphylococcus or Streptococcus bacteria and occurs at sites of skin trauma such as bites, scratches, or cuts.
Symptoms present as a tiny cluster of fluid-filled blisters that weep after bursting and form a crust. Fluids at these sites, as well as the nasal fluids of persons who harbor the causative agent in their nose, carry infection and allow for easy transmission between people. Washing sores with antibacterial soap and covering them can prevent transmission of the bacteria.
Treatment with antibiotics is usually very effective, and sores generally heal slowly without scarring. Prevention is achieved through good hygiene practices such as handwashing and treatment of other skin sores to prevent establishment of infection. Impetigo and its causative pathogens (disease-causing organisms) are found throughout the world.
Disease History, Characteristics, and Transmission
Impetigo is a skin disorder that results from bacterial infection, commonly by Staphylococcus aureus but also by Streptococcus bacteria. Infection usually occurs when the protective barrier of the skin is irritated or breached due to cuts, scratches, insect bites, or eczema.
The disease is one of the most common among children and is characterized by crusting skin lesions usually located around the nose, mouth, hands, and forearms. Symptoms begin as small pimplelike sores surrounded by reddened skin, which quickly develop into fluid-filled blisters. Once the blisters rupture, that patch of skin will continue to weep and a yellowish crust will develop over four to six days. The lesions may vary slightly depending on the causative agent, but generally symptoms have the same presentation and will appear around two to three days after infection.
Impetigo is extremely contagious and transmission occurs through contact with the infected site, nasal fluid, or fomites (items such as clothing and bedding that contain infected material on their surface). Scratching may also spread the lesions.
WORDS TO KNOW
COLONIZATION: Colonization is the process of occupation and increase in number of microorganisms at a specific site.
FOMITE: A fomite is an object or a surface to which an infectious microorganism such as bacteria or viruses can adhere and be transmitted. Transmission is often by touch.
PATHOGEN: A disease causing agent, such as a bacteria, virus, fungus, etc.
IN CONTEXT: REAL-WORLD RISKS
Impetigo refers to a very localized bacterial infection of the skin. It tends to afflict primarily children, but can occur in people of any age. Impetigo caused by the bacteria Staphylococcus aureus (or staph) affects children of all ages, while impetigo caused by the bacteria called group A streptococci (Streptoccus pyogenes or strep) are most common in children ages two to five years.
Scope and Distribution
Those most commonly affected by impetigo are toddlers and school children between the ages of two and six years old, with peak incidence usually occurring in the hot and humid weather of the summer months. The disease tends to occur in small outbreaks, although epidemics are rare.
Impetigo often follows a recent upper respiratory tract infection caused by streptococcus bacteria, and people who suffer from cold sores may also have a higher chance of developing the disease.
There is often no apparent source of infection for impetigo. This is due largely to the fact that Staphylococcus aureus is part of the human body's normal flora, which means that it is one of many bacteria that readily colonize areas of the human body without causing infection. Staphylococcus bacteria are commonly found on the skin's surface, nose, and mouth and cause infection when they enter open wounds at these sites.
Treatment and Prevention
The focus of treatment for impetigo is to cure the infection and to relieve symptoms. If the infection is limited to a small area, a topical antibiotic ointment will generally be sufficient. If this is not effective, oral antibiotics may be required. Healing will begin within a few days of treatment and sores generally clear within ten days without severe scarring.
Prevention of impetigo may be achieved by maintaining good hygiene practices such as regular handwashing, bathing, and tending to skin injuries such as cuts, scrapes, bites, and rashes. To prevent passing along infection, infected sites should be covered and items such as linen and cutlery should not be shared.
Impacts and Issues
Impetigo, although often widespread, generally poses little threat to communities and treatment is readily available in developed countries. The ease of transmission between people infected is heightened among groups of young children where limiting contact can prove difficult. In situations of outbreak among school groups, it is important that parents and teachers work together to ensure the infected children are appropriately and effectively treated while those not infected are successfully protected.
Evidence suggests that geography and climate will influence the primary infective organism causing impetigo. In developing nations and warmer climates, Streptococcus bacteria is the most common. In rare cases, impetigo caused by Streptococcus bacteria can progress deeper than the skin. One such complication arising from infection by Streptococcus may lead to damage of the kidneys, heart, or other organs. This makes early detection and treatment important in these developing regions.
IN CONTEXT: EFFECTIVE RULES AND REGULATIONS
The Centers for Disease Control and Prevention (CDC), Coordinating Center for Infectious Diseases, Division of Bacterial and Mycotic Diseases states that The spread of all types of GAS infection (Group A Streptococcal Disease (strep throat, necrotizing fasciitis, impetigo) can be reduced by good handwashing, especially after coughing and sneezing and before preparing foods or eating. Persons with sore throats should be seen by a doctor who can perform tests to find out whether the illness is strep throat. If the test result shows strep throat, the person should stay home from work, school, or day care until 24 hours after taking an antibiotic. All wounds should be kept clean and watched for possible signs of infection such as redness, swelling, drainage, and pain at the wound site. A person with signs of an infected wound, especially if fever occurs, should seek medical care. It is not necessary for all persons exposed to someone with an invasive group A strep infection (i.e. necrotizing fasciitis or strep toxic shock syndrome) to receive antibiotic therapy to prevent infection. However, in certain circumstances, antibiotic therapy may be appropriate. That decision should be made after consulting with your doctor.
SOURCE: Centers for Disease Control and Prevention (CDC), Coordinating Center for Infectious Diseases, Division of Bacterial and Mycotic Diseases
See AlsoBacterial Disease; Childhood Infectious Diseases, Immunization Impacts; Handwashing; Microorganisms; Staphylococcus aureus Infections; Strep Throat.
BIBLIOGRAPHY
Books
Mandell, G.L., J.E. Bennett, and R. Dolin. Principles and Practice of Infectious Diseases, vol. 2. Philadelphia, PA: Elsevier, 2005.
Mims, C., H. Dockrell, R. Goering, I. Roitt, D. Wakelin, and M. Zuckerman. Medical Microbiology. St. Louis, MO: Mosby, 2004.
Web Sites
Health Protection Agency. “Impetigo: Factsheet for Schools.” <http://www.hpa.org.uk/infections/topics_az/wfhfactsheets/WFHImpetigo.htm> (accessed March 6, 2007).
Medline Plus. “Impetigo.” Feb. 26, 2007 <http://www.nlm.nih.gov/medlineplus/ency/article/000860.htm> (accessed March 6, 2007).