What are Staphylococcal infections?

What are Staphylococcal infections?

• Staphylococcal infections are a group of infections caused by the bacterium Staphylococcus.
• The most common of this group of bacteria is Staphylococcus aureus.
• Staphylococcal infections are spread by skin-to-skin contact and often start by infecting small cuts in the skin.
• However there is a wide spectrum of Staphylococcal infections, both in terms of severity and how easily they can be treated.

What are the symptoms of Staphylococcal infections?

• Staphylococcal infections occur when the bacterium gets into the body through a break or cut in the skin.
• Depending on how far the bacterium gets into the body, Staphylococcal infections are usually divided into two groups:
  • skin and soft tissue infections
  • invasive infections.

Skin and soft tissue infections

• Skin and soft tissue Staphylococcal infections include:
  • Boils: painful, red bumps on the skin of the neck, face, thighs, armpits and buttocks
  • Impetigo: a highly contagious bacterial skin infection causing painful sores and painless blisters
  • Cellulitis: a bacterial infection of the deep layer of the skin and the layer of fat and soft tissue beneath the skin. This can cause patients to feel feverish and nauseous.

Invasive infections

• Invasive Staphylococcal infections include:
  • Sepsis: also known as blood poisoning, this happens when Staphylococcal infections enter the blood stream causing an overwhelming immune response.
    • Symptoms include fever, fast heartbeat, low blood pressure, diarrhoea, pale and cold skin, and sometimes loss of consciousness. Sepsis is a medical emergency.
    • Toxic shock syndrome is a form of severe sepsis. It is a rare but life-threatening infection caused by Staphylococcus aureus releasing a toxic substance. It causes a high fever, a dramatic drop in blood pressure (shock), dizziness and confusion.
  • Septic arthritis: a condition where a joint becomes infected with Staphylococcus aureus bacteria causing joint swelling, pain and fever.
  • Endocarditis: this is when Staphylococcus infects the internal structures of the heart (for example, the heart valves), causing inflammation.
    • Symptoms can develop gradually over the space of many weeks, or quickly over the space of a few days.
    • Symptoms include chest pain, coughs, fatigue, shortness of breath, fever and unexplained weight loss.

How do you treat Staphylococcal infections

• Skin and soft tissue infections are generally mild and straightforward to treat with antibiotic tablets or creams.
• The more invasive the infection, the harder it is to treat.
• Once the bacteria penetrate the skin and enter the blood, they can multiply rapidly, releasing toxins and creating considerable damage to organs and tissues.
• In these incidences doctors may have to resort to antibiotic injections.

A plate of Staphylococcus aureus
Image credit: User:Valugi – Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons

What are the challenges in treating Staphylococcal infections?

• Many strains of Staphylococcal bacteria have developed antibiotic resistance.
• Methicillin-resistant Staphylococcus aureus, more commonly known as MRSA, is a type of Staphylococcus aureus that is resistant to a number of antibiotics including methicillin.

What is methicillin-resistant Staphylococcus aureus (MRSA)?

• MRSA (methicillin-resistant Staphylococcus aureus) is a form of staphylococcal infection that is resistant to methicillin. It is often resistant to other commonly used antibiotics as well.
• Because of its antibiotic resistance, MRSA can be very difficult to treat and often spreads quickly in contained spaces such as hospitals, nursing homes and even gyms and homeless shelters.
• It is sometimes referred to as a ‘superbug’.
• Hospitalised patients are at the highest risk of getting an MRSA infection because they are frequently in contact with other people who are likely to have MRSA.
• Many hospitalised patients are older and weaker making them more susceptible to developing an MRSA infection that could become life-threatening.
• In general, the perfect environments in which MRSA can spread are places which have poor hygiene, large numbers of people passing through and lots of skin-to-skin contact. These conditions mean the bacteria can be easily transferred from person to person.

Methicillin-resistant Staphylococcus aureus (MRSA).

Image credit: Genome Research Limited

Is MRSA always harmful?

• Many of us live with Staphylococcus aureus and MRSA without any problems. Many people have S. aureus living in their nose or on their skin.
• Most people who acquire MRSA become silent carriers of the bacterium and do not exhibit any symptoms.
• Only a small proportion of these carriers go on to develop infection if the bacteria enter their body through an area of broken skin, such as a wound.
• MRSA causes more problems than regular S. aureus because it is resistant to antibiotics commonly used to treat Staphylococcal infections. This makes it much more difficult to get rid of.

How can the spread of MRSA be prevented?

• MRSA infections have put a huge strain on healthcare systems.
• In recent years, increased awareness of the infection has allowed healthcare professionals to manage it more effectively.
• Prevention techniques include:
  • washing hands before and after visiting someone in a care home or hospital to avoid the spread of any bacteria that may be on the hands (MRSA can be spread by skin-to-skin contact)
  • screening patients for MRSA before they are admitted to hospital for an operation. This is most often done with swabs taken from the nose and groin, or by testing a blood, urine, tissue or spit sample.
  • putting all disposable items, such as dressings and gloves, into the appropriate bins promptly to avoid cross-contamination
  • a policy of patients being encouraged to speak to their nurse or doctor if they are worried about hygiene standards on a ward.

How is MRSA treated?

• To identify the best course of treatment for an individual with an MRSA infection the doctor will assess the type, site and severity of the infection.
• They will also find out which antibiotics that the specific strain of MRSA is resistant and sensitive to.
• Minor skin or soft tissue infections such as boils may only need to be treated superficially, with a technique called ‘incision and drainage’.
• This is where the surface of a boil is broken open with a sterile scalpel, sometimes under a local anaesthetic, and the pus is drained out, relieving pressure and pain for the patient.
• Despite being resistant to a number of different antibiotics, some strains of MRSA can be treated effectively with other antibiotics or a combination of antibiotics.
• These antibiotics are often given as injections and may be given for up to six weeks, depending on the severity of the infection.