Infection can develop in any type of wound. In certain types of wounds and certain circumstances, developing an infection is more likely. There are a number of precautions to take which help to prevent wound infections developing. In most cases wound infections can be cured with an antibiotic cream or medicine.
What is a wound infection?
A wound is a damaged area of the body, usually involving a break to the skin. Wounds can be surgical (a cut made during an operation in order to do the procedure) or due to trauma. Traumatic wounds could be a result of falls, accidents, fights, bites or weapons. They may be cuts, lacerations, grazes, etc. Both surgical and traumatic wounds may have been closed with stitches, glue or sticky tapes, to help healing. In some wounds this closure is not needed. This is because the wound is small or the edges are close together.
Wounds may be closed rather than open. For example, a punch can leave you with a bruise but no break in the skin. Wounds may also be chronic, meaning they have persisted over a few weeks or more. Ulcers come into this group of wounds. Ulcers are discussed further in the separate leaflets called Pressure Ulcers, Venous Leg Ulcers and Diabetes, Foot Care and Foot Ulcers.
Wounds heal best when they are clean and free from germs. In a wound infection, germs have got into the area where the skin is broken. There may be infection in a small area around the edge, or in the whole wound site, or spreading further.
Surgical wound infections are also called "surgical site infections" (SSIs).
Why do wounds become infected?
Normally, many germs live harmlessly on our skin and in the environment around us. These germs are microscopic, which means they are so tiny they can't be seen by the naked eye. You need a microscope to see them. There are a number of types of germs, such as bacteria, viruses and fungi. Normally the germs live on our skin, or in areas such as our nose, without causing any problems to us. If the skin is broken, however, and they spread into the more sensitive tissues underneath, they start to cause an infection. This makes the tissues sore and swollen, and less likely to heal. Open wounds are more likely than closed wounds to develop infections. This is because the break in the skin provides a route for the germs to travel from the outside to the inside. Normally the skin acts as a barrier.
Some circumstances make it more likely that wounds will become infected. These include:
- If you have diabetes type 1 or type 2.
- If the object which caused the wound was dirty and contained germs.
- If the wound was caused by a human or animal bite.
- If the wound still contains a "foreign body", ie bits of whatever caused the injury. For example, bits of glass, splinters of wood, thorns, etc.
- The size and depth of the wound. Larger or deeper wounds have a higher chance of becoming infected.
- Jagged edges to the wound.
- If proper precautions were not taken before an operation.
- If you are an older person. Your skin heals less well as you get older.
- If you are very overweight.
- If your immune system does not work as well as normal. For example, if you are on medication such as steroids or chemotherapy, or if you have HIV/AIDS.
How can I tell if my wound is infected?
A wound which has become, or is becoming, infected may:
- Become more painful, instead of gradually improving.
- Look red around the skin edges. This red area may feel warm or hot.
- Look swollen.
- Ooze a yellow material (pus) which may be smelly.
If the infection spreads further, the redness will keep spreading to more areas of skin. You may feel unwell in yourself, with a temperature (fever) and aches and pains.
What should I do if I think my wound is infected?
If you think a cut from an operation (a surgical wound) is infected, you should see the nurse or doctor at your surgery as soon as possible. They may take a sample of any discharge from the wound with a stick which looks like a large cotton bud, called a swab. This can be sent to the laboratory to find out which germs are causing the infection. Your nurse or doctor will help keep your wound clean, and prescribe treatment if needed (see below.)
If you have a laceration, cut or graze, keep a close eye on it. If a very small injury has become just a little bit red, you may be able to prevent further infection. Keep it clean by bathing it with warm water and clean cotton wool. Try an antiseptic cream, such as Savlon®. If the redness is spreading or the wound starts to ooze pus then see your doctor or nurse. If it is a larger wound and seems to be developing infection then see your doctor or nurse straightaway.
How are wound infections treated?
Unless the infection is very minor, antibiotics are usually needed to treat the infection and stop it spreading. If the wound and/or area of infection is small then an antibiotic cream such as fusidic acid may be prescribed. If the wound is larger, or the infection seems to be getting worse, then an antibiotic to be taken by mouth (oral antibiotic) is needed. One of a number of antibiotics may be used for wound infections. Commonly used ones include:
The nurse will also cleanse your wound and provide suitable dressings to cover and protect it.
What are the complications of a wound infection?
If a wound infection is not quickly and successfully treated, it may spread. The skin around may become red and swollen and sore. The infection may spread to the deeper tissues beneath the skin. This spreading infection is called cellulitis. As the infection spreads, it may spread through the blood right through your system, making you feel unwell in yourself. This can give you a temperature (fever) and may develop into severe infection called sepsis.
Other possible complications include:
- The wound may not heal properly if it is infected.
- Other types of skin infection, such as impetigo.
- It can turn into a painful lump of pus called an abscess.
Very rare complications include:
- Developing a further infection with tetanus (see below).
- Developing a further infection called necrotising fasciitis, known as the "flesh-eating bug". This is a very rare severe condition where large areas of the skin become very damaged and painful.
How can I prevent wound infection?
Preventing infection in surgical wounds
Your team at the hospital have strict procedures to try to help avoid infections. Surgical infections are monitored by Public Health England, so that policies can be changed and improved if needed. Examples of the types of procedures they follow are:
- Swabs of your nose and skin to check for certain germs before the operation.
- Cleansing of the skin to be operated on beforehand.
- Strict handwashing with special surgical soap.
- Wearing gloves and clean surgical clothes ("scrubs") and shoes. The operating team wear sterile gowns over the surgical clothes.
- Prescribing "in case" (prophylactic) antibiotics for operations which have a high risk of infection.
There are a number of things you can do yourself to reduce your chances of infection. For example:
- Have a shower or bath before your operation and wash yourself with soap and water.
- Do not use a razor to shave the area to be operated on. This makes infection more likely. If the hair needs to be removed, your surgical team will do this with clippers.
- Remove all jewellery and nail polish before the operation.
- Keep the wound covered and the area around it clean. You can shower from two days after most operations.
- If you notice the skin around the wound becoming red or painful, see your doctor or nurse as soon as possible.
Preventing infection in traumatic wounds
Tips to avoid infection of traumatic wounds:
- Clean the wound and skin around it as soon as it happens. Use cool boiled water, or drinking-quality water.
- If you think there are still bits of foreign bodies in the wound, see your surgery nurse or go to your nearest Minor Injuries Unit or Accident & Emergency to have it professionally cleaned out.
- If it is a very deep wound, or the edges are very far apart, or you cannot stop the bleeding go to your nearest Minor Injuries Unit or Accident and Emergency in case it needs stitches.
- Use an antiseptic around the wound area to help keep the germs away.
- Put a clean dressing over your wound to protect it from germs. Do not use gauze or a type of dressing which will stick to the wound. Your pharmacist should be able to advise you if the wound is too big for an ordinary plaster.
- Bites are very likely to become infected - seek medical advice at the earliest signs of this. If the injury is large, or there are multiple bite wounds, it may be worth having antibiotics "in case". Seek advice straightaway in this case, rather than waiting for signs of infection to develop.
- Keep a close eye on the wound and seek medical advice if you think infection is developing.
- Arrange for a tetanus vaccination if needed (see below).
Do I need a tetanus injection?
Tetanus is a serious disease caused by germs which mostly live in soil or manure. Wounds which have been in contact with soil or manure, or which are particularly "dirty", may put you at risk of developing tetanus. Most people are protected from tetanus by the routine vaccination programme. Five injections are required, usually given in stages to children as they are growing up. The first one is given to babies starting at 2 months of age and the last one at around the age of 15 at school. If you have a "dirty" wound and have not had the full tetanus vaccination course, or if you are not sure, see a nurse as soon as possible. If it is not possible to check your vaccination status, you will normally be given a booster dose. If you have had the full course, you will not need a further injection. See separate leaflet called Tetanus Immunisation for more details.
What is MRSA?
MRSA stands for meticillin-resistant Staphylococcus aureus. It is a type of germ (bacterium) which is resistant to many antibiotics. It commonly lives harmlessly on our skin or in our nose or throat but may cause an infection in people in hospital. To reduce this problem, for some operations you may be screened for MRSA before your operation. At your "pre-op" check you may have swabs taken from your nose, your skin and sometimes other areas. These will be sent to the laboratory. If MRSA is found, you will be given a course of antibiotic cream to get rid of the germs. This helps to prevent a wound infection after your operation. See separate leaflet called MRSA for more details.
Dr Mary Harding
Dr Mary Harding
Dr Hayley Willacy