What is Impetigo?
Impetigo is a common skin infection that affects the surface layer of the skin, known as the epidermis. It’s highly contagious, meaning it can easily spread to others, and is usually caused by certain types of bacteria. Common symptoms include red skin patches topped with a yellow crust, which can be itchy or painful.
This skin infection is more common in children living in warm, humid climates. There are two types of impetigo: bullous (where large blisters form) and nonbullous (where small blisters form that burst and leave red raw patches of skin). While it commonly affects the face, impetigo can also occur on any area of the body with a cut, scab, insect bite, or any skin damage.
The diagnosis of impetigo is usually made based on symptoms and the appearance of the skin. The treatment for this infection generally involves using skin creams or ointments that contain an antibiotic (to kill bacteria) and taking oral antibiotics. It may also include treatments to soothe the symptoms, such as creams or lotions to relieve itching.
What Causes Impetigo?
Impetigo, a skin infection, is responsible for about 10% of skin conditions seen in children. Both boys and girls are equally likely to get it, no matter their age. However, among adults, men are more often affected. Although impetigo can happen at any age, it’s most common in children between 2 and 5 years old. Also, more cases are seen during the summer and fall months.
There’s a form of this skin infection called bullous impetigo that’s more common in babies. In fact, children under two make up 90% of all bullous impetigo cases.
Risk Factors and Frequency for Impetigo
Nonbullous impetigo, a skin infection, is mostly caused by a bacteria called S. aureus, which is involved in about 80% of cases. Another culprit, Group A beta-hemolytic Strep (GABHS), causes about 10% of these infections, while in another 10% of cases, a combination of these two bacteria is responsible. Methicillin-resistant S. aureus (MRSA), a highly drug-resistant bacteria, is becoming increasingly common, especially among people in healthcare facilities. Additionally, in recent times, there has been a quick rise in community-acquired MRSA. The condition is especially prevalent among groups living in close confines, such as daycare centers and prisons.
On the other hand, Bullous impetigo, a different kind of skin infection, is largely caused by S. aureus alone. Sometimes, it can lead to a deeper, ulcerated infection known as ecthyma, which is essentially a complication of bullous impetigo.
Signs and Symptoms of Impetigo
There are three types of impetigo skin infections: nonbullous impetigo, bullous impetigo, and ecthyma.
Nonbullous impetigo begins with tiny bumps filled with liquid which often merge and break open, forming a yellowish crust on the skin. It often affects the face and hands, especially where there is broken skin. This type often spreads quickly, forming more spots. Some people may experience slight swelling of the nearby glands. Generally, people with nonbullous impetigo do not have fever.
On the other hand, bullous impetigo starts with small, liquid-filled bumps that turn into thin-walled blisters. This is due to a toxin made by the S. aureus bacteria which interferes with the skin cells sticking together. The blisters carry a clear or yellow liquid which may become cloudier later. Unlike nonbullous impetigo, bullous impetigo spots don’t form a honey-colored crust, are fewer in number, and are found in different areas, like body creases or inside the mouth. Despite that, people with bullous impetigo may have fever more often than people with nonbullous impetigo.
Ecthyma is a more severe form of impetigo where sores reach deeper into the skin. The sores look like they have been punched out, with purple-like edges. The crusts over the sores could be honey-colored or dark brown. These sores could also be filled with pus.
Testing for Impetigo
A patient’s medical history and a physical examination by a doctor play vital roles in diagnosing impetigo, a skin infection. Lab tests called bacterial cultures can be used to confirm this diagnosis. Your doctor may perform these tests if they suspect that the germ causing the infection is a type of tough-to-treat bacteria called methicillin-resistant staph aureus (MRSA), or if there’s an ongoing outbreak of impetigo.
In some cases, an unhealed or stubborn case of impetigo may require a skin biopsy. A skin biopsy is a procedure where a small piece of the infected skin is removed to be closely examined under a microscope.
However, blood tests for streptococcal antibodies aren’t typically helpful in diagnosing impetigo because the body’s immune response to the bacteria that causes impetigo is generally weak. These tests, called anti-streptolysin O (ASO), measures the body’s response to a strep infection. But it could be of use if the patient shows signs of another related disease called post-streptococcal glomerulonephritis following a recent outbreak of impetigo.
If a previously healthy adult develops a severe form of impetigo called bullous impetigo, which is characterized by large fluid-filled blisters, an HIV test might be recommended. This is because certain illnesses can be indicative of a weakened immune system, as seen in conditions like HIV.
Treatment Options for Impetigo
Impetigo is a common skin infection that is often treated with topical antibiotics or a combination of topical and systemic (taken by mouth or injected) antibiotics. These antibiotics target the bacteria S aureus and S pyogenes, which commonly cause impetigo.
Although impetigo can sometimes get better on its own, antibiotics can help speed up healing, decrease the number of sores, and reduce the risk of complications. Without treatment, impetigo could lead to complications involving the kidneys, joints, bones, lungs, or even lead to acute rheumatic fever, a serious condition that affects the heart.
For mild impetigo, that is localized, uncomplicated, and non-bullous (doesn’t cause fluid-filled blisters), topical treatment alone is normally the best approach. Before applying the topical antibiotic, the skin crust should be gently washed off with soap and water. The types of topical antibiotics typically used for treating impetigo are mupirocin, retapamulin, and fusidic acid.
Oral or injectable antibiotics are recommended for severe impetigo conditions. This includes cases labeled as bullous impetigo (which causes larger, fluid-filled blisters), non-bullous impetigo with more than five lesions or sores, any deep tissue infection, systemic symptoms of infection, swollen lymph nodes, or sores within the mouth. The preferred oral antibiotics are those that the bacteria can’t easily resist, such as cephalosporins, amoxicillin-clavulanate, and dicloxacillin. If streptococci bacteria is the only confirmed cause, oral penicillin is typically given.
In regions where MRSA, a type of bacteria resistant to many antibiotics, is common or if a patient’s specific infection tests positive for MRSA, treatments may include antibiotics such as clindamycin or doxycycline. If the impetigo is not caused by group A streptococci bacteria, then they might also use an antibiotic called trimethoprim-sulfamethoxazole.
During an active impetigo outbreak, children should maintain good personal hygiene and avoid close contact with others to prevent spreading the infection. This includes handwashing and cleaning items that may have come into contact with the infected sores. Covering sores with a bandage can also help reduce the risk of spread. If impetigo reoccurs frequently, it might be because the bacteria are living in the nose; to address this, a specific antibiotic called mupirocin can be applied inside the nostrils.
What else can Impetigo be?
These are some skin conditions that have symptoms similar to each other:
- Atopic dermatitis (commonly known as eczema)
- Scabies (a skin infestation caused by a mite)
- Contact dermatitis (a rash caused by contact with certain substances)
- Herpes simplex (a viral infection, includes cold sores and genital herpes)
- Candidiasis (a fungal infection, also known as yeast infection)
- Varicella zoster (the virus that causes chickenpox and shingles)
What to expect with Impetigo
If left untreated, the infection will usually clear up on its own in about two to three weeks. In fact, about 20% of these cases get better without medical intervention. Scarring is uncommon, but some individuals might see changes in the color of their skin. Some individuals might develop a more serious skin infection called ecthyma.
On the other hand, with treatment, individuals can expect to recover within about 10 days. It is particularly important to treat newborns promptly, as they can sometimes develop an infection of the membranes and fluid surrounding their brain and spinal cord, a condition known as meningitis. Also, there is a rare complication, called acute post streptococcal glomerulonephritis. This condition – which typically occurs two to three weeks after the skin infection – can impair the kidneys’ ability to filter waste and extra fluid from the body.
Possible Complications When Diagnosed with Impetigo
While most people get better with treatment, a small number might have kidney failure. This becomes more likely if the streptococcus bacteria caused the infection. The kidney problems usually appear one to two weeks after the infection starts. The temporary presence of blood (hematuria) and excess protein (proteinuria) in the urine can persist for several weeks or even months. Other potential issues include joint infection (septic arthritis), scarlet fever, bloodstream infection (sepsis), and a condition that causes blistering and peeling of the skin (staphylococcal scalded skin syndrome).
Possible Complications:
- Kidney failure
- Temporary blood in urine (hematuria)
- Excess protein in urine (proteinuria)
- Joint infection (septic arthritis)
- Scarlet fever
- Bloodstream infection (sepsis)
- Condition causing blistering and peeling of the skin (staphylococcal scalded skin syndrome)
