1. Facts About MRSA
What Is MRSA?
Methicillin-resistant Staphylococcus aureus (MRSA) refers to strains of the bacterium Staphylococcus aureus (S. aureus), commonly referred to as staph, that are resistant to certain antibiotics (specifically, methicillin, a narrow-spectrum β-lactam antibiotic in the penicillin class, and other β-lactamase and penicillin antibiotics). Changes in the genetic makeup of S. aureus strains have given some bacteria the ability to become resistant to these antibiotics. S. aureus or staph is usually found in the nose and on the skin of about 30% of healthy individuals, while MRSA is found in only 2% of healthy individuals.1 People who carry S. aureus or MRSA but do not have symptoms of an infection are considered to be colonized with the bacteria.
What Is a MRSA Infection?
People who have symptoms associated with MRSA or S. aureus colonizationare considered to have a MRSA or S. aureus infection. In the past, MRSA infections were typically confined to people who had been hospitalized; these infections are referred to as hospital-acquired MRSA (HA-MRSA) infections. However, MRSA infections can also be acquired by people who have not been hospitalized; these are known as community-acquired MRSA (CA-MRSA) infections.2
Signs and Symptoms of a MRSA Infection
Skin infections caused by CA-MRSA typically start as reddened and inflamed patches, pimples or bumps on the skin that may be painful, swollen or warm to the touch. If left untreated, these can develop into abscesses that drain pus and other fluids, or cellulitis (an infection of the tissues beneath the skin), or can cause fever. It’s not possible to determine whether you have a skin infection caused by MRSA just by looking at the infection, so you should see a doctor if you think you might have a MRSA infection, especially if the symptoms are accompanied by a fever.1
In healthcare settings, MRSA is one of the leading causes of surgical site infections, bloodstream infections and pneumonia. These can occur in patients who have breaks in the skin that can allow the bacteria to enter the tissues or bloodstream, or in patients taking antibiotics, which can reduce the normal flora on the skin, giving MRSA an advantage.3 The symptoms of these infections are varied depending on the site of the infection but may include fever, chills, the draining of pus or other fluids, pain and swelling, a mucus-filled cough and stabbing pains in the chest. Life-threatening sepsis resulting from the body’s natural response to fighting infection may occur if left untreated.4
How Is MRSA Diagnosed?
MRSA infections are typically diagnosed if the organism can be successfully cultured (grown) from a sample taken from a wound or infected site. This typically takes about 48 hours. Newer diagnostic tests that identify DNA specific to MRSA are becoming available and can give a diagnosis in a matter of hours.5
Who Is at Risk?
Anyone is at risk of acquiring CA-MRSA. However, the CDC has identified five factors — the five Cs — that may make it easier for people in locations where these exist to acquire MRSA.6 These are Crowding, frequent skin-to-skin Contact, Compromised skin (i.e., cuts or abrasions), Contaminated items and surfaces, and lack of Cleanliness. These factors are commonly found in schools, dormitories, military barracks, athletic gyms, households, correctional facilities, daycare centers, urban underserved communities, veterinary clinics and livestock settings.6 For example, athletes, especially those involved in sports with skin-to-skin contact such as wrestling, are particularly at risk, but there have been many reports of high-profile athletes contracting MRSA.7 Outbreaks have also occurred in the families of people who have had MRSA surgical site infections, and in people participating in group activities such as camping.2 Because CA-MRSA usually manifests as a skin infection, people who are confined in close quarters such as detainees in jails or prisons, or who are in physical contact with each other such as athletes, are particularly at risk.
For HA-MRSA infections, because MRSA can enter any open wound or break in the skin (e.g., those resulting from IV catheter insertions), anyone who is hospitalized is at risk.8 Patients at higher risk include those who are already colonized with MRSA on admission to the hospital,9 those who have an IV line insertion or an invasive procedure such as a surgery, and long-term care facility residents.10