Babies get impetigo when common bacteria enter their skin through small breaks like scratches, insect bites, or patches of eczema. The infection is caused by two types of bacteria that are already widespread in the environment and on human skin, so it doesn’t take much for a baby to pick it up. Impetigo is the most common bacterial skin infection in children, and babies are especially vulnerable because their skin is thin and easily damaged.
The Bacteria Behind Impetigo
Two bacteria cause nearly all cases of impetigo: Staphylococcus aureus (staph) and Streptococcus pyogenes (strep). Staph is responsible for about 80% of non-bullous impetigo cases on its own, strep causes around 10%, and the remaining 10% involve both bacteria together. These organisms are extremely common. Many healthy people carry staph on their skin or inside their nose without ever developing an infection.
Not every baby whose skin comes into contact with these bacteria will develop impetigo. The bacteria need a way past the skin’s outer barrier to take hold. Once they get through, they attach to protein receptors in the deeper layers of skin and begin multiplying, creating the characteristic sores.
How the Bacteria Reach Your Baby’s Skin
There are three main routes. The most common is direct skin-to-skin contact. A sibling, parent, or playmate who has impetigo (or who carries the bacteria without symptoms) can transfer it through touching, cuddling, or sharing a bed. Babies in daycare are at higher risk simply because they’re in close quarters with other children who may be infected.
The second route is through contaminated objects. Towels, blankets, toys, clothing, and pacifiers can all harbor the bacteria. According to the Cleveland Clinic, the bacteria that cause impetigo can survive on dry surfaces for weeks or even months. A baby who mouths a shared toy or is dried with a towel used by someone with active sores can easily pick up the infection.
The third route is self-inoculation. If a baby already carries staph in their nose, they can spread it to other parts of their own face, especially around the nostrils and mouth, through normal touching and rubbing.
What Gives Bacteria a Way In
Intact skin is a strong barrier, even in babies. The bacteria almost always need a break in the skin to establish an infection. Common entry points include:
- Eczema patches: Babies with atopic dermatitis have chronically disrupted skin, making them significantly more likely to develop impetigo.
- Insect bites: A single mosquito bite that a baby scratches open is enough.
- Minor cuts and scrapes: The everyday nicks that come with crawling, bumping into furniture, or scratching their own face with fingernails.
- Diaper rash or drool rash: Any area where skin is already irritated and raw.
- Chickenpox blisters: Open or healing pox lesions are a well-documented entry point.
Impetigo that develops on previously healthy skin is called primary impetigo. When it forms on top of an existing wound or skin condition, it’s called secondary impetigo. In babies, secondary impetigo on top of eczema is particularly common.
Bullous vs. Non-Bullous Impetigo
There are two forms, and babies are more prone to one of them. Non-bullous impetigo is the more common type overall. It starts as small red sores, usually around the nose and mouth, that quickly burst and leave behind honey-colored crusts. This form can be caused by either staph or strep.
Bullous impetigo produces larger, fluid-filled blisters that look fragile and pop easily. It’s caused almost exclusively by staph, which produces a toxin that breaks down the bonds between cells in the top layer of skin. This is the form that disproportionately affects infants. Children under two account for 90% of bullous impetigo cases. The blisters often appear on the trunk, arms, and diaper area rather than the face.
Why Babies Are More Susceptible
Several factors converge to make infants especially vulnerable. Their immune systems are still maturing, so they’re less equipped to fight off bacterial colonization before it becomes an active infection. Their skin is thinner and more permeable than adult skin. They also can’t control their scratching, so a small irritation can quickly become an open wound. Babies who attend daycare, live in warm or humid climates, or have siblings with active skin infections face the highest risk.
How Impetigo Is Treated in Babies
For a small number of localized sores, the standard treatment is a prescription antibiotic cream applied directly to the affected skin. Topical antibiotics are more effective than placebo and generally preferred over oral antibiotics when the infection is limited to a small area. The most commonly prescribed option is mupirocin 2% cream or ointment, applied to the sores for several days.
If the infection is widespread, involves large blisters, or appears in hard-to-treat areas, an oral antibiotic may be needed. Penicillin alone is not effective against impetigo. If a doctor suspects a resistant strain of staph (MRSA), the antibiotic choice will be adjusted accordingly.
With treatment, impetigo typically clears within 7 to 10 days. The sores are considered contagious until they’ve crusted over and begun healing, or until 24 to 48 hours after antibiotic treatment starts.
Preventing Spread at Home
Because the bacteria survive on surfaces for a long time, prevention involves both hygiene and separation of personal items. Wash your baby’s towels, washcloths, bedding, and clothing in hot water and don’t share them with other family members during an active infection. Clean toys and hard surfaces regularly, especially items your baby mouths.
Keep your baby’s fingernails trimmed short to minimize scratching, which both creates entry points for bacteria and spreads existing sores to new areas of skin. If your baby has eczema, staying on top of their moisturizing routine helps maintain the skin barrier and reduces the risk of secondary impetigo. Gently wash sores with soap and water, then cover them loosely with a bandage to limit contact with other children or shared surfaces.
If your baby is in daycare, most facilities will require them to stay home until the sores are no longer contagious. Letting the daycare know promptly can help prevent a wider outbreak among other children in the group.