Impetigo is a contagious skin infection characterized by red sores or blisters that often crust over. While direct contact with the sores is the most frequent way the infection moves between people, a primary concern is the risk of indirect spread from contaminated objects in the environment. Understanding how long the bacteria can persist on household surfaces is important for managing the risk of transmission.
The Bacterial Agents and Transmission
Impetigo is caused by two main types of bacteria: Staphylococcus aureus and Streptococcus pyogenes. These microbes typically enter the body through a break in the skin, such as a cut, scrape, or insect bite, leading to the characteristic skin lesions. The infection is most commonly spread through direct skin-to-skin contact with the fluid that oozes from the blisters and sores of an infected person.
However, the bacteria can also be transmitted indirectly by touching objects that an infected individual has used. These contaminated items, known as fomites, can include shared towels, clothing, bedding, and children’s toys. While this indirect route is less frequent than direct contact, it remains a relevant path for the bacteria to spread, especially in household or school settings.
Survival Time on Non-Living Surfaces
The bacteria responsible for impetigo can survive on inanimate objects for extended periods, making environmental decontamination a necessary step in infection control. Both Staphylococcus aureus and Streptococcus pyogenes are classified as Gram-positive bacteria, a group known for its ability to persist on dry surfaces. Research indicates that these organisms can remain viable on non-living materials for days to months, depending on the specific surface and surrounding conditions.
Staphylococcus aureus has been shown to survive on hard, non-porous surfaces like plastic and stainless steel for days, and sometimes for several months. On soft surfaces, such as fabrics and hospital linens, this bacterium can persist for up to nine weeks. This ability to tolerate a lack of moisture contributes to the longevity of the bacteria outside the body.
Streptococcus pyogenes also exhibits a capacity for survival on dry surfaces, with viability reported in studies ranging from a few days up to six and a half months. Environmental factors play a role in this duration, as cooler temperatures and higher humidity levels are associated with a longer survival time for both types of bacteria. Contaminated items within a home environment can serve as a reservoir for the infection for a considerable duration if not properly cleaned.
Decontaminating the Environment
Cleaning and disinfection practices are required to mitigate the risk of indirect transmission. All personal items that come into contact with the infected person’s skin or lesions should be handled separately to prevent bacterial spread. This includes clothing, towels, washcloths, and bed linens, which should be changed and laundered daily.
Laundry Procedures
For laundry, items should be washed using hot water, preferably at 60 degrees Celsius or higher, with a detergent that contains active oxygen bleach. If washing at a lower temperature, the addition of a bleach-containing detergent is important to ensure the destruction of the microbes. High-heat drying cycles also contribute to the elimination of residual bacteria on fabrics.
Surface Disinfection
Hard surfaces that are frequently touched, such as doorknobs, countertops, light switches, and shared toys, must be routinely disinfected. This cleaning should involve the use of approved disinfectants or a simple bleach solution, which is effective against the impetigo-causing bacteria. It is advisable to use disposable gloves when cleaning the affected areas or handling contaminated materials to protect the caregiver and limit the spread of bacteria to other surfaces.