Wound Infection: Causes, Symptoms and Treatment

What Is a Wound Infection?

A wound infection occurs when bacteria, fungi, or other pathogens enter a wound and begin to multiply. The immune system responds with an inflammatory reaction. Wound infections can develop after injuries, surgical procedures, or in the context of chronic wounds, significantly delaying natural healing. Without timely treatment, the infection can spread to surrounding tissue or enter the bloodstream, causing life-threatening complications.

Causes

Wound infections are caused by pathogens entering open or poorly healing wounds. Contributing risk factors include:

• Inadequate wound hygiene or improper wound care
• A weakened immune system (e.g., in diabetes mellitus, HIV, or during chemotherapy)
• Poor blood circulation to the affected tissue
• Foreign bodies in the wound (e.g., splinters, dirt)
• Deep or heavily contaminated injuries
• Postoperative wounds with insufficient sterility
• Chronic conditions such as peripheral arterial disease

Common Pathogens

Bacteria are the most common cause of wound infections. These include:

• Staphylococcus aureus (including MRSA)
• Streptococcus pyogenes
• Escherichia coli and other gram-negative bacteria
• Pseudomonas aeruginosa (especially in chronic wounds)
• Anaerobes such as Clostridium species (e.g., in gas gangrene or tetanus)

Symptoms

The typical signs of a wound infection correspond to the classic features of inflammation:

• Redness (rubor) around the wound
• Swelling (tumor) of the affected tissue
• Warmth (calor) at the wound site
• Pain (dolor) or increasing tenderness
• Purulent or foul-smelling wound discharge
• General malaise, fever, or chills when systemic involvement occurs
• Delayed or absent wound healing

Diagnosis

Diagnosis is primarily clinical, based on the appearance of the wound. Additional investigations may include:

• Wound swab with microbiological culture to identify the pathogen and test antibiotic resistance
• Blood tests (e.g., CRP, white blood cell count, procalcitonin) to assess systemic inflammation
• Imaging studies (ultrasound, MRI) if deep tissue infection or abscess formation is suspected

Treatment

Local Wound Care

The foundation of treatment is thorough wound cleansing and removal of dead tissue (debridement). Necrotic tissue and foreign bodies are removed, as they impair healing and provide a breeding ground for pathogens.

Antiseptic Wound Dressings

Depending on the pathogen and severity of the infection, antiseptic wound irrigation solutions (e.g., polihexanide, octenidine) or specialized antimicrobial wound dressings may be applied.

Antibiotic Therapy

Bacterial infections with systemic involvement or deep tissue infiltration require antibiotic treatment. The choice of antibiotic is guided by the identified pathogen and its resistance profile. Commonly used agents include penicillins, cephalosporins, and clindamycin.

Surgical Intervention

Abscesses must be surgically opened and drained. In severe infections such as necrotizing fasciitis or gas gangrene, immediate surgical debridement can be lifesaving.

Prevention

Wound infections can largely be prevented through appropriate measures:

• Prompt and proper wound care after injuries
• Sterile technique during surgical procedures
• Regular wound monitoring and dressing changes
• Optimal management of underlying conditions (e.g., blood glucose control in diabetes)
• Tetanus vaccination for deep or contaminated wounds

References

1. World Health Organization (WHO): Global Guidelines for the Prevention of Surgical Site Infection. WHO Press, 2016.
2. Lipsky B.A. et al.: 2012 Infectious Diseases Society of America Clinical Practice Guideline for the Diagnosis and Treatment of Diabetic Foot Infections. Clinical Infectious Diseases, 2012.
3. Dissemond J. et al.: Evidence-based therapy of chronic wounds. Journal of the German Society of Dermatology (JDDG), 2021.