Wound infection: Causes and symptoms of wound infections

When pathogenic organisms invade viable tissue of a wound, a wound infection occurs. An infection of the wound activates the body’s immune response, causing inflammation and subsequent tissue damage. This reaction causes a delayed healing process. Many infections clear up on their own, but other infections, left untreated, lead to more serious wounds. Good wound care is therefore important.

  • Causes of wound infection: Through opening in skin
  • Defense of the skin
  • Often due to staphylococcal bacteria
  • Risk factors of wound infections
  • Diseases
  • Environmental factors
  • Symptoms of infected wounds
  • Diagnosis and examinations
  • Treatment for infected wounds
  • Prevention is better than cure
  • Antibiotics and wound care
  • Improve blood circulation
  • Lifestyle advice
  • Medication
  • Complications


Causes of wound infection: Through opening in skin

Defense of the skin

The skin surface is protected by the acid mantle (a thin, acidic film produced by the sebaceous glands). This acid mantle ensures that pathogens do not enter the body. Pathogens often displace some of the normal skin flora and colonize certain locations, but this usually does not lead to an infection or trigger an immune response. With broken skin or a weak immune system, the microorganisms colonize the skin or penetrate the wound, causing an infection.

Often due to staphylococcal bacteria

An infected wound is a wound that has been colonized by bacteria or other microorganisms, which has either delayed wound healing or worsened the appearance of the wound itself. Wound infections also appear when the body’s natural defenses are weakened and the body cannot cope with normal bacterial growth. Most infected wounds are the result of bacterial colonization, originating from normal skin flora, or from bacteria from other parts of the body or the outside environment. The most common bacteria that leads to a wound infection is Staphylococcus aureus / MRSA (bacterial infection with resistance to antibiotics), but other types of staphylococci can also cause skin infections. For example , Streptococcus pyogenes (streptococcal infection), Enterococci and Pseudomonas aeruginosa are some other well-known bacteria that lead to wound infection.

Risk factors of wound infections

Being overweight increases the risk of a wound infection / Source: Tobyotter, Flickr (CC BY-2.0)


Patients with a poorly functioning or weak immune system are more likely to contract a wound infection. Certain conditions lead to non-healing wounds and are more likely to result in infection, especially when the patient suffers from poor blood circulation. Diabetes mellitus, varicose veins, malnutrition, obesity, peripheral vascular disease and Raynaud’s disease increase the risk of an infected wound.

Environmental factors

Reduced mobility or immobility is often the basis of a wound infection. Furthermore, an uncovered wound or poor wound cleaning allows bacteria to penetrate the cracked skin more quickly, resulting in wound infections. Smoking also gives rise to an infected wound more quickly. Medicines may also slow down or prevent wound healing, resulting in an infection. This happens more quickly with the following medications:

  • anticoagulants (anticoagulants)
  • corticosteroids (powerful anti-inflammatories)
  • immunosuppressants (drugs that suppress the immune system)
  • nonsteroidal anti-inflammatory drugs (NSAIDs)


Symptoms of infected wounds

The wound infection occurs in many types of wounds such as scratches, animal bites, cuts, puncture wounds, incisions (surgical incisions), pressure wounds, small and large burns. The clinical presentation of a wound infection consists of fever, chills, redness, tenderness, swelling, induration, skin discoloration, inflammation, bleeding and increasing pain. In addition, purulent pus (cloudy, yellow or green in color) comes from the wound. A warm spot will also develop around the incision. The size and color of the wound are subject to changes with a wound infection. The wound also emits a foul-smelling odor. Due to these symptoms, wound healing is delayed or otherwise the wound worsens.Non-specific symptoms also occur, such as loss of appetite, malaise (a general ill feeling), nausea, vomiting, fatigue, lack of energy or a decrease in glycemic control in diabetics.

Diagnosis and examinations

The doctor will have the following tests carried out, the main purpose of which is to determine the type of wound infection that is necessary for appropriate treatment:

  • antimicrobial sensitivity
  • a bacterial culture
  • a blood culture
  • a gram stain
  • a fungal culture


Treatment for infected wounds

Prevention is better than cure

It is important to minimize the risk of wound infections, which is especially important in patients at risk. Fast and correct wound cleaning is necessary to reduce the biological burden. After surgery, patients are given antibiotics to reduce the incidence of wound infectionsAntibiotics are necessary / Source: Stevepb, Pixabay

Antibiotics and wound care

The doctor examines whether the infection is systemic or whether there is only a localized wound area that is infected. Systemic treatment often requires oral (taken by mouth) antibiotics. The doctor treats local infections with local antibiotics (applied to the skin). Draining pus or removing dead tissue is sometimes necessary, because these factors slow down wound healing and the antibiotics no longer work as efficiently. Antimicrobial dressings and silver dressings can be used to reduce biological burden. Good wound care is essential to prevent wound infection and help the wound heal faster.

Improve blood circulation

Improving blood circulation often prevents a wound infection. Regular exercise and lifting the wounds or limbs help improve blood flow.

Lifestyle advice

During the treatments, the patient must also consume a healthy diet (full of fruit and vegetables), drink or be given sufficient fluid, stop smoking and maintain a good and healthy weight.


If certain medications cause a wound infection, a patient must stop taking them under the supervision of a doctor. The doctor may also prescribe other medications.


A wound infection is the most common hospital infection in surgical patients. Due to the infected wound, the patient often has to stay in the hospital for a long time, which entails higher costs. The most serious local complication of an infected wound is arrested wound healing, resulting in a non-healing wound. This often results in significant pain, discomfort and psychological harm to the patient. Systemic complications also occur, such as:

  • amputation
  • cellulitis (bacterial skin infection of the deeper layers of the skin with red and swollen skin)
  • an abscess
  • gangrene (tissue death with changes to the skin)
  • necrotizing fasciitis (death of the skin due to flesh-eating bacteria)
  • osteomyelitis (bacterial infection of the bone or bone marrow)
  • secondary impetigo (bacterial skin infection with symptoms on the face and extremities)
  • septicemia (bacterial presence in the blood potentially leading to an inflammatory state of the entire body)
  • tetanus (bacterial infection with muscle contractions)


read more

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  • Poor wound healing: Causes of slow or sluggish recovery