Impetigo is a common and contagious bacterial infection of the skin, most frequently observed in infants and young children. This condition begins with the appearance of small, reddish sores, which quickly develop into blisters that often burst. Once ruptured, the sores typically ooze and then form a characteristic yellowish-brown or “honey-colored” crust. This crust can spread to other areas of the body through touch. Understanding how the causative bacteria survive outside the human body is paramount to preventing its spread.
The Bacteria Behind Impetigo
The infection is primarily caused by two types of hardy Gram-positive bacteria. Most cases are attributed to Staphylococcus aureus (Staph), and sometimes to Streptococcus pyogenes (Group A Strep). These bacteria enter the body through a break in the skin, such as a cut, scrape, or insect bite, though they can also colonize otherwise healthy skin. Identifying the specific bacteria guides the antibiotic treatment prescribed by a healthcare provider. Both Staph and Strep are known for their resilience, allowing them to persist on inanimate objects, or fomites, which is the primary reason the infection can spread indirectly.
Environmental Survival Time
The bacteria responsible for impetigo are robust outside of a host and can remain infectious on household items. Studies have shown that Gram-positive bacteria can survive for an extended duration on dry, inanimate surfaces. This survival time is often measured in weeks to months, making them persistent sources of transmission.
The exact duration depends on several environmental factors, including the type of surface and the ambient conditions. Non-porous surfaces like plastic toys, doorknobs, or countertops may harbor viable bacteria for longer than porous materials. Temperature also plays a role, as a cooler environment is generally associated with a longer survival time for most bacteria.
Humidity is another factor, with some research suggesting that S. aureus can persist longer in low-humidity conditions. Common items in the home, such as towels, bed linens, clothing, and cribs, have all been identified as potential reservoirs for these organisms.
Preventing Surface Transmission
Effective control requires both rigorous environmental and personal hygiene measures. Focusing on environmental cleanliness limits the number of bacteria available for indirect spread.
Environmental Cleaning
Contaminated items, including clothing, bed linens, and towels used by the infected person, should be washed separately. Laundering these items in hot water is recommended to ensure the bacteria are eliminated. Hard surfaces and frequently touched objects, such as counters, doorknobs, light switches, and toys, should be routinely disinfected. Using a household bleach solution or an EPA-registered disinfectant effectively neutralizes the bacteria on these surfaces.
Personal Hygiene
Personal hygiene practices are important to stop the cycle of contamination. The infected person’s sores must be kept clean and covered with a bandage or clean clothing to prevent discharge from touching surfaces or other people. Caregivers should wear gloves when applying topical treatments and wash their hands thoroughly immediately afterward. Frequent and thorough handwashing with soap and running water is essential for everyone in the household. Avoiding the sharing of personal items, such as washcloths and towels, and keeping fingernails trimmed short prevents the spread of bacteria.