OVERVIEW

What is wound infection?

Wound infection refers to the inflammatory response that occurs when bacteria invade a wound or a treated wound site after trauma. Symptoms include localized redness, swelling, heat, and pain. In severe cases, systemic symptoms such as fever, fatigue, generalized weakness, and swollen lymph nodes may also occur ^[1].

What are the types of wound infections?

1. Based on the duration of infection, wound infections can be classified as ^[2,3]:

   1. Acute infection: Short-term infection with obvious symptoms, usually resolving within three weeks. Commonly seen in sudden traumatic wounds like abrasions, contusions, or puncture wounds.
   2. Chronic infection: Long-term infection, typically lasting over two months, with more subtle symptoms. Often observed in individuals with chronic conditions, such as diabetic foot in diabetes patients or pressure ulcers in bedridden individuals.

2. Based on the type of pathogen, wound infections can be classified as ^[2,3]:

   1. Non-specific infection: Also known as general or purulent infection, commonly caused by bacteria like Staphylococcus, Streptococcus, or Escherichia coli, and usually acute in nature.
   2. Specific infection: Caused by specific pathogens such as Clostridium tetani, Candida albicans, or Bacillus anthracis. The wound manifestations vary depending on the pathogen—for example, tetanus bacteria may cause redness, swelling, and ulceration, while Candida albicans may lead to white fungal growth at the wound site.

Are wound infections common?

Wound infections are very common. Trauma frequently occurs in daily life, such as accidental cuts while cooking, abrasions from falls, or surgical wounds from medical procedures. Improper care can easily lead to infection. Among these, surgical site infections are one of the most common hospital-acquired infections ^[2-4].

SYMPTOMS

What Are the Common Manifestations of Wound Infection?

1. Manifestations of Wound Infection ^[2,3]

   1. Redness: The skin around the wound appears red, distinctly different from uninjured areas, due to inflammation-induced congestion.
   2. Heat: The skin temperature at and around the wound is noticeably higher than other body parts.
   3. Swelling: Infection in the wound and surrounding tissues leads to congestion and edema.
   4. Pain: The wound itself causes pain, which worsens as the infection progresses.
   5. Others: Additional symptoms may include bleeding, oozing, pus discharge, or a foul odor. Chronic infections may result in prolonged non-healing of the wound.

2. Systemic Infection Manifestations ^[2,3]

   1. Fever: Acute infections often present with sudden high fever (>39°C), while chronic infections may cause persistent low-grade fever (37.5–38°C).
   2. Increased Pulse Rate: Systemic infection can lead to elevated heart and pulse rates (exceeding 100 beats per minute).
   3. Fatigue: Patients may experience weakness, exhaustion, or persistent tiredness unrelieved by rest.

What Are the Complications of Wound Infection?

1. Sepsis: If pus is not drained promptly, bacteria may spread systemically via lymphatic or blood vessels, causing widespread infection. Symptoms include chills, high fever (>39°C), and altered mental status (e.g., confusion or delirium).
2. Septic Shock: Caused by severe infection, it manifests as sudden loss of consciousness and a sharp drop in blood pressure (systolic pressure <90 mmHg) ^[3].

CAUSES

What are the common causes of wound infections?

1. Microbial factors: Bacterial infections are the most common causative agents of wound infections and the most frequent cause of acute infections. Staphylococcus aureus is the most common gram-positive coccus leading to surgical infections, followed by Staphylococcus epidermidis, Enterococcus faecalis, and Enterococcus faecium ^[2-4].
2. Immune factors: Weakened immunity and insufficient local barrier defenses make it difficult to resist bacterial and viral invasions ^[2-4].
   3.Increased bacterial resistance: Due to the widespread and irrational use of broad-spectrum antibiotics, bacterial resistance to antimicrobial drugs continues to rise, rendering common antibiotics ineffective in preventing infections ^[2-4].

Are wound infections contagious? What are the transmission routes of wound infections?

Wound infections caused by bacterial factors are contagious. The transmission route is contact-based: infected wound → hands or objects that come into contact with the wound → other uninfected wounds ^[3].

DIAGNOSIS

How to Determine if a Wound is Infected?

1. Acute wound infection can be diagnosed based on typical clinical manifestations (redness, swelling, heat, and pain in the wound). If the infection symptoms are severe, laboratory tests such as a blood count (checking for elevated white blood cell levels) may also be performed ^[3].

2. Smear culture and examination of abnormal secretions on the wound surface can identify the infecting bacteria ^[3].
3. For chronic wound infections, in addition to the above diagnostic criteria, the following manifestations may also be present ^[2]:
   1. Excessive granulation tissue: Abnormal growth of granulation tissue in the infected wound.
   2. Increased tissue fragility and susceptibility to bleeding: The wound is easily re-injured or bleeds during the healing process, or fails to heal properly.
   3. Epithelial bridging or pockets in granulation tissue: This requires examination with specialized tools.
   4. Wound breakdown or enlargement.
   5. Failure to heal within the expected timeframe: Wounds that do not heal within three to four weeks are generally considered delayed.
   6. Increased pain or newly developed pain.
   7. Increased foul odor, such as a putrid smell.

TREATMENT

Which department should I visit for wound infection?

General surgery or infectious diseases department.

Can wound infections heal on their own?

Superficial skin abrasion infections can heal on their own, but it is important to keep the wound clean to avoid worsening symptoms due to continuous contamination. Such wounds include skin abrasions, scratches, and needle punctures (rust-free needles; if rusty, seek immediate medical attention).

Larger wounds, such as surgical wounds or deep cuts, require immediate hospital treatment.

How is wound infection treated?

Mainly treated with antibiotics ^[3].

1. Can be administered intravenously, orally, or topically. It is a conventional treatment for bacterial infections and is suitable for all populations.
2. Commonly used drugs include cefoperazone-sulbactam, amoxicillin, clarithromycin, roxithromycin, cefaclor, and levofloxacin.
3. Primary function: controls bacterial infections.
4. Main adverse reactions: gastrointestinal discomfort (e.g., nausea, vomiting), skin allergies (e.g., itching, rashes).
5. Contraindications: allergy to the prescribed antibiotics.

Besides medication, what other treatments are available for wound infections?

1. Physical therapy: A commonly used clinical treatment, including local hot compresses, ultrashort wave therapy, or infrared radiation therapy. Improves local blood circulation and promotes inflammation resolution ^[3].

2. Surgical debridement or surgery: Suitable for severe wounds that are difficult to heal on their own. For cases with significant abscess formation, incision and drainage may be performed. For example, pressure ulcers can be treated with surgical debridement ^[3].

Does wound infection require hospitalization?

Localized wound infections usually do not require hospitalization. However, if systemic symptoms (e.g., fever, fatigue) are present, or in cases of chronic infections caused by underlying diseases (e.g., diabetes) or surgical wound infections, hospitalization may be necessary.

DIET & LIFESTYLE

What should be paid attention to in diet for wound infection?

1. Healthy diet: Strengthen nutrition by providing a high-energy, vitamin-rich, high-protein, and easily digestible diet (such as one egg per day; milk, more than 300 mL daily). Ensure adequate hydration (more than 1500 mL per day) and consume plenty of fresh vegetables and fruits (vegetables, at least three handfuls daily; fruits, at least two handfuls daily). Maintain a balanced diet ^[4]. The goal is to enhance the body's resistance and promote wound healing ^[3,5].
2. Avoid alcohol or reduce the intake of alcoholic beverages. Alcohol can easily interact with medications (such as cefuroxime), requiring special attention.

What should wound infection patients pay attention to in daily life?

Protect the wound to avoid secondary damage and worsening infection.

For superficial wounds, keep them clean and dry. If the wound becomes dirty, promptly clean it with drinking water or boiled-cooled water, disinfect with iodine, and bandage with sterile gauze ^[3]. For surgical wounds, change dressings regularly without delay, and ensure the surrounding environment is hygienic and safe during dressing changes.

How can wound infection patients avoid transmitting the infection to others?

Maintain cleanliness and protection of the wound area. Dispose of items that come into contact with the wound promptly. For example, dressings from tetanus-infected patients should be incinerated ^[3] and kept separate from clean items.

Is follow-up necessary for wound infection?

The need for follow-up depends on the cause of the wound infection and its healing progress.

Surgical wound infections and chronic wound infections require follow-up, with the timing and frequency determined by the doctor. For other wound infections, if symptoms worsen or the wound fails to heal over time, prompt medical attention is needed to identify the cause.

PREVENTION

Can wound infections be prevented?

Wound infections can be prevented.

1. In daily life, take precautions to avoid injuries.
2. Maintain hygiene in diet and living environments to reduce bacterial growth.
3. Keep living spaces dry and well-ventilated, maintaining suitable temperature and humidity (generally, room temperature should be controlled at 18–22°C, with humidity at 50–60%) ^[6].
4. Cultivate healthy lifestyle habits, exercise scientifically (ideally walking 6,000 steps daily) ^[4] to boost immunity.
5. Individuals with chronic conditions (e.g., diabetes) should take extra care to avoid wounds, monitor their health closely, and seek medical attention promptly if abnormalities occur ^[7].
6. For narrow and deep wounds caused by wood splinters or rusty nails, seek medical attention immediately and get a tetanus vaccine ^[3].
7. Before or after surgical procedures, preventive antibiotic treatment under a doctor’s guidance can reduce the risk of infection ^[3,8].