Surgical Site Infections: Causes, Symptoms & Treatments

Surgical Site Infections: Causes, Symptoms & Treatments
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Medically Reviewed By:
Mark Arredondo, M.D.

A surgical site infection (SSI) is an infection that happens where you had surgery.

SSIs happen in 2% to 4% of people who have surgery while in the hospital, says the Agency for Healthcare Research and Quality. Even though most infections can be treated with antibiotics, SSIs can still lead to serious problems and sometimes even death after surgery.

In this article, experts explore what SSIs are, what causes them, their types, symptoms and how they can be treated.

What is a surgical site infection?

An SSI is an infection that happens after surgery in the area where the surgery was performed, according to the U.S. Centers for Disease Control and Prevention. Some SSIs are minor, affecting only the skin, while others can be severe, involving tissues beneath the skin, organs or implanted materials, according to the CDC. These infections occur in the body part where the surgery took place.

Causes of surgical site infections

Infections after surgery result from harmful germs, with Staphylococcus, Streptococcus, and Pseudomonas bacteria being the most common culprits. “SSIs, and specifically DSWIs [deep sternal wound infections], are dreaded complications of cardiac surgery,” Dr. Edward Soltesz, Cleveland Clinic’s director of cardiac surgery affiliate and alliance programs, said in a recent Cleveland Clinic article.

According to Johns Hopkins Medicine, these germs can infiltrate surgical wounds through different means, like contact with contaminated caregivers or instruments, airborne germs or traveling from your body into the wound.

The risk of a surgical site infection depends on the type of surgical wound:

  • Clean wounds: These are uncontaminated, non-inflamed wounds that don't involve internal organs

  • Clean-contaminated wounds: These wounds don't indicate any sign of infection before surgery but involve internal organ operations

  • Contaminated wounds: These occur when surgery involves an internal organ with contents spilling into the wound

  • Dirty wounds: These wounds have a known infection during surgery

Surgical site infections can occur during your hospital stay, even after you've left the operating room. Factors such as the hospital's cleanliness, adherence to infection control measures and the type of surgical procedure you had can influence the risk of developing an infection.

Types of surgical site infections

SSIs are a significant health care challenge. These infections result in considerable illness and mortality, with over 2 million cases reported among hospitalized patients in the United States.

The CDC classifies surgical wound infections into three categories, according to StatPearls:

  • Superficial incisional infections: These involve only the skin and subcutaneous tissues. They constitute more than half of all surgical infections

  • Deep incisional infections: These affect deeper tissues, including muscles

  • Organ/space infections: These involve organs other than the incision site, linked to the surgical procedure

Surgical site infection symptoms

Any SSI may display redness, fever, pain, tenderness, delayed healing, warmth or swelling.

Additional symptoms are linked to specific SSI types:

  • A superficial incisional SSI may result in pus discharge from the wound, which can be cultured to identify the infecting germs

  • Deep incisional SSIs may also produce pus, and the wound may reopen spontaneously or be reopened by a surgeon to reveal pus

  • Organ or space SSIs may exhibit pus draining from a skin-placed drain or form an abscess, seen when the wound is reopened or through special X-rays

Surgical site infection treatment

Mount Sinai outlines the following standard courses of surgical site infection treatment:


In most cases, antibiotics are prescribed to combat wound infections. The duration of treatment typically spans at least one week, often starting with intravenous antibiotics and transitioning to oral pills. Completing the entire antibiotic course is essential, even if you start feeling better. In instances of wound drainage, testing may determine the most effective antibiotic. Methicillin-resistant Staphylococcus aureus (MRSA) infections require specific antibiotics.

Surgical treatment

Sometimes, surgical intervention is necessary to address the infection. Procedures can occur in the operating room, hospital room or clinic. Steps include wound opening, pus or tissue analysis, dead tissue removal, wound rinsing, pus drainage (if needed), and wound packing and bandaging.

Wound care

Regular wound cleaning and dressing changes are often needed. Patients can learn to do this themselves or have nurses perform it. In some cases, a vacuum-assisted closure (VAC) dressing enhances healing by increasing blood flow. Healing times can vary, with some wounds taking days, weeks or even months to fully heal. If a wound doesn't close naturally, a skin graft or muscle flap surgery may be required for post-infection clearance.

Living with a surgical site infection

Surgical site infections are temporary and, although healing time can vary from days to months, they will eventually clear up.

For less severe infections with small openings, self-care at home is possible. Deeper infections or larger openings might require a hospital stay. After that, you'll continue to care for yourself at home with nurse visits or go to a nursing facility.

Remember to contact your health care provider if your surgical wound exhibits any signs of infection, including pus, foul odor, fever, warmth, redness or pain.


Agency for Healthcare Research and Quality: Surgical Site Infections

U.S. Centers for Disease Control and Prevention: Frequently Asked Questions About Surgical Site Infections

Johns Hopkins Medicine: Surgical Site Infections

StatPearls: Postoperative Wound Infection

Mount Sinai: Surgical Wound Infection – Treatment

U.S. National Library of Medicine (MedlinePlus): Surgical Wound Infection – Treatment

What This Means For You

Getting a surgical site infection after an operation is the last thing anyone wants. Here, experts discuss its causes, symptoms and treatments.

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