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Infection After Surgery - Causes, Prevention, and Treatment

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5 min read


Infections after surgery frequently occur that are treatable and easily preventable. Read the article to know more about infection after surgery.

Written by

Dr. Anahita Ali

Medically reviewed by

Dr. Pandian. P

Published At February 27, 2023
Reviewed AtFebruary 27, 2023


Infections after surgery are common but serious problems as they are the most frequent hospital-acquired infection (HAI). Such infections increase the economic and financial burden on the patient and the healthcare system. The occurrence of infection after surgery may require another surgery, a long hospital stay, and extra treatment expenses that negatively impact the patient's mental and physical health.

Every year, millions of people undergo surgical procedures. Approximately two percent of surgeries develop surgical site infections. Surgical site infections are caused by the germs that enter the patient’s body through the surgery area or surgical site. There are patient-related factors and procedure-related factors that cause an infection after surgery. If infection prevention is poorly practiced, the chances of getting an infection after the surgery become very high. These infections are common yet easily preventable.

What Is Infection After Surgery?

Infection is the entry of harmful germs or bacteria into the body that multiplies in number and causes a reaction in the body. It occurs at the site of surgery within 30 days and involves one of the following:

  • Infection involving only skin or subcutaneous tissue of the incision or cut.

  • Drainage from the superficial incision.

  • Organism identification from the fluid drainage or tissue through culture.

  • Presence of at least one sign and symptom of infection.

  • Diagnosis of infection by the doctor.

What Are the Other Common Names of an Infection After Surgery?

It is commonly known as surgical site infection (SSI), post-operative infection, or postoperative wound infection.

How Are Surgical Wound Infections Classified?

Infection of the postoperative wound is a frequent medical issue. The intricate nature of wound infection requires molecular interactions between multiple biological pathways. Consequently, wound infections are a major cause of morbidity and mortality. The Centers for Disease Control and Prevention (CDC) has classified surgical wound infections as follows:

Superficial Incisional Infection:

Skin and the subcutaneous tissues alone are affected. At least one symptom of wound infection, purulent discharge from the site, an isolated organism, and a surgeon's diagnosis are necessary. Of all surgical infections, these infections make up more than 50 percent.

Deep Incisional Infections:

Deeper tissues, such as muscles and fascial planes, are involved. Dehiscence, purulent discharge from the wound, or purposeful reopening of a deep incision by the surgeon when an infection is suspected, abscess formation, or the surgeon's diagnosis of other deep infections are the criteria that must be accomplished.

Organ/Space Infection:

Any organ may be involved, excluding the incision area, but it must be connected to the surgery. In addition, a purulent discharge from an organ drain, an isolated organism from the organs, an abscess, or any other organ infection must be present.

For the wound to be considered a surgical site infection, it must:

  • Only affect the skin, subcutaneous tissues, deep layers, or distant organs.

  • Occur within 30 days of the surgery (in the event of organ/space infections with an implant in situ, this is one year).

  • Have purulent discharge, or have organisms isolated from the wound site.

Any infected wound opened by the surgeon to clean it is considered an infected surgical wound. If a wound has a stitch abscess, it is not seen as infectious. Most surgical wound infections are brought on by endogenous flora, typically found on the skin, hollow viscera, or mucous membranes. There is a considerable chance of an infected wound when the microbial flora is more than10,000 germs/gm of tissue.

What Are the Examples of an Infection After Surgery?

Infections occur commonly after the following surgeries:

What Are the Types of Surgical Site Infections?

There are three types of surgical site infections (SSI) based on the severity of the infection:

  1. Superficial Incisional SSI - The infection occurs only at the site of surgery, where the incision or cut was made.

  2. Deep Incisional SSI - The infection occurs under the incision or cuts at the surgery site, infecting the muscles and surrounding tissues under the incision.

  3. Organ or Space SSI - The infection occurs anywhere within the body except the surrounding skin, tissues, or muscles at the surgical site. The infection occurs in the organs or the space present between the organs.

What Are the Signs and Symptoms of Infection After Surgery?

Common signs and symptoms are:

  • Redness or swelling at the surgery site.

  • Pus drainage or abscess.

  • Fever.

  • Delayed healing.

  • Pain.

What Is the Most Common Time Frame When a Patient Gets an Infection After Surgery?

Infection can occur from two to three days after surgery until the wound has completely healed (three weeks). Generally, an infection occurs within 30 days of surgery. However, if an implant is placed within the body, such as a metal plate, the infection may occur within one year of surgery.

What Causes Infection After Surgery?

Certain risk factors and underlying bacteria cause an infection after surgery.

  • Infection-causing bacteria or germs, commonly Staphylococcus, Streptococcus, and Pseudomonas.

  • Other risk factors, such as contaminated or uncleaned surgical instruments.

  • Existing medical diseases such as diabetes.

  • Elder age of the patient.

  • The weak immune system of the patient.

  • The habit of smoking.

  • Overweight.

  • Poor nutritional status of the patient.

  • Steroid use before surgery.

How to Prevent Infection After Surgery?

The World Health Organization (WHO) recommends 29 guidelines to prevent infection after surgery. The prevention steps for the patient before and after surgery are listed below:

Before Surgery:

  • Before the surgery, provide information about recent illness or disease and other infections, such as urinary tract infection, vomiting, etc., that require antibiotics.

  • Good body wash.

  • If the patient has diabetes, the blood sugar levels should be in control.

  • Smoking should be quit one month before surgery because it interferes with healing and increases the risk of infection.

  • The surgical site should not be shaved.

  • Prophylaxis should be considered, and an antibiotic must be given 30 to 60 minutes before the surgery.

After Surgery:

  • Maintain good hand hygiene by frequent hand washing.

  • Good body washes with disinfectant soap.

  • Practice breathing exercises.

  • Avoid touching the surgery site.

  • Keep the upper body part a little high while resting. This reduces the risk of respiratory infection.

How to Treat Infection After Surgery?

Most infections are treatable. If an infection occurs after the surgery, the following can be done:

  • Antibiotics are prescribed to treat most infections. The antibiotic prescription depends on the type and severity of the infection. These can be given orally or through intravenous injections.

  • Sometimes, additional surgery may be required. If there is pus or abscess, then reopening of the surgical site may be required to drain out the pus - debridement.

What Are the Chances of Infection After Surgery if the Doctor Does Not Prescribe an Antibiotic After Surgery?

There are evidence-based international guidelines for the prevention of surgical site infections given by the World Health Organization. According to these 29 guidelines, an antibiotic prescription must be practiced only before and during the surgery and not after surgery. If the patient and medical professionals follow these guidelines appropriately before, during, and after the surgery, there are fewer chances of infection. In addition, these guidelines emphasize preventing antibiotic resistance among patients that develops because of the unnecessary overuse of antibiotics.


Infections after surgery can lead to serious health issues if not prevented or treated. The rate of infection may vary according to the type of surgery. Before undergoing any surgery, it is important to stay aware and identify the risk factors that may cause or increase the risk of infection.

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Dr. Pandian. P
Dr. Pandian. P

General Surgery


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