What causes impetigo in adults

Overview

Impetigo is a common bacterial skin infection that primarily affects infants and children, but it can also occur in adults. It is characterized by red sores that quickly rupture, ooze, and then form a yellowish-brown crust. While generally not serious, impetigo is highly contagious and requires prompt treatment to prevent spreading and complications.

Causes of Impetigo in Adults

The root cause of impetigo in adults, just as in children, is infection by specific types of bacteria. The two main culprits are:

• Staphylococcus aureus (Staph): This is the most common bacterium responsible for impetigo, estimated to cause about 70% of all cases. Staph bacteria are commonly found on the skin and in the nose of many healthy people without causing harm. However, when they gain entry into the skin through a break, they can cause infection.
• Streptococcus pyogenes (Strep throat bacteria): This bacterium is the second most frequent cause of impetigo. Like Staph, these bacteria are often present on the skin or in the throat of individuals without causing illness.

These bacteria typically enter the skin through minor injuries such as cuts, scrapes, insect bites, or even existing skin conditions like eczema or psoriasis. Once inside, they multiply and trigger an inflammatory response, leading to the development of impetigo sores.

Risk Factors for Impetigo in Adults

While anyone can develop impetigo, certain factors can increase an adult's susceptibility:

• Compromised Immune System: Individuals with weakened immune systems due to conditions like HIV/AIDS, cancer, or those undergoing chemotherapy are more vulnerable to infections, including impetigo.
• Pre-existing Skin Conditions: Adults with chronic skin issues such as eczema, dermatitis, psoriasis, or skin that has been damaged by sunburn are more prone to bacterial entry and subsequent infection.
• Diabetes: People with diabetes may have impaired circulation and a higher risk of skin infections.
• Poor Hygiene: Inadequate hygiene practices can create an environment where bacteria can thrive and more easily infect the skin.
• Close Contact with Infected Individuals: Working or living in close proximity to someone with impetigo, especially in crowded environments like dormitories or nursing homes, increases the risk of transmission.
• Hot and Humid Climates: These conditions can promote bacterial growth and skin irritation, making infection more likely.

Types of Impetigo

There are two main forms of impetigo:

• Non-bullous Impetigo: This is the most common type, accounting for about 70% of cases. It begins as small red spots that turn into blisters. These blisters rupture, leaving behind moist, red sores that eventually dry into a characteristic honey-colored crust.
• Bullous Impetigo: This less common form is usually caused by Staphylococcus aureus. It is characterized by larger, fluid-filled blisters, typically on the trunk, arms, and legs. These blisters are usually painless initially but can rupture and form a crust.

A more serious, deeper form of impetigo called ecthyma can also occur, which penetrates deeper into the skin, causing painful, pus-filled sores that can lead to scarring.

How Impetigo Spreads

Impetigo is highly contagious and spreads easily through:

• Direct Skin-to-Skin Contact: Touching the sores of an infected person.
• Contact with Contaminated Objects: Sharing towels, clothing, bedding, or toys that have come into contact with the bacteria.
• Autoinoculation: An infected person touching their sores and then touching another part of their own body, spreading the infection.

When to See a Doctor

It is important to consult a healthcare professional if you suspect you have impetigo. Early diagnosis and treatment are crucial to:

• Prevent the spread of the infection to others.
• Reduce the risk of complications, such as cellulitis (a deeper skin infection), kidney inflammation (post-streptococcal glomerulonephritis), or scarring.
• Speed up the healing process.

A doctor can usually diagnose impetigo based on its appearance. In some cases, a swab of the sore may be taken to identify the specific bacteria and determine the most effective antibiotic treatment.

Treatment and Prevention

Treatment for impetigo typically involves topical or oral antibiotics prescribed by a doctor. Good hygiene practices are also essential for preventing the spread and recurrence of impetigo. This includes washing hands frequently, keeping the infected area clean and covered, and avoiding sharing personal items.