Methicillin-resistant Staphylococcus epidermidis (MRSE) is a drug-resistant form of staph bacteria. MRSE infections may be difficult to treat due to their resistance to methicillin and other common antibiotics.

MRSE is different from methicillin-resistant Staphylococcus aureus (MRSA). They are both staph bacteria that can cause infections resistant to several antibiotics, but they are different species of these bacteria.

Due to MRSE’s resistance to several antibiotics, some healthcare professionals may also refer to it as multi-drug resistant Staphylococcus epidermidis.

Treatment typically involves alternative antibiotic therapy.

This article aims to provide a comprehensive overview of MRSE, covering its definition, symptoms, causes, diagnosis, and treatment.

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MRSE refers to a species of staph bacteria that is resistant to methicillin and other beta-lactam antibiotics, which are a subtype of antibiotics.

Older studies cited in a 2020 study indicated that methicillin resistance is present in 75–90% of Staphylococcus epidermidis (S. epidermidis) hospital isolates. These are samples of microorganisms that healthcare professionals take from people staying in a hospital to analyze in a laboratory.

Given this, S. epidermidis can result in infections that are difficult to treat with antibiotics.

The S. epidermidis bacterium is commonly present on human skin and mucous membranes, such as in the nose.

Although typically harmless, these bacteria can enter the body via an opening in the skin, such as a surgical wound or the site of an implanted medical device. Once in the bloodstream, MRSE can cause severe complications, such as sepsis and septic shock.

Symptoms of MRSE infections can vary depending on the cause. They can include localized (occurring in one body part or organ) or systemic (spread throughout the body) symptoms.

Some symptoms a person may experience include:

In severe cases, a person may start demonstrating signs of sepsis, such as a fever and low blood pressure.

Several factors may contribute to a person developing an MRSE infection.

MRSE infection is among the most common types of blood infection a person may acquire in a hospital in the United States. The infection can occur in a surgical wound or near a medical device. People with the following medical devices are the most at risk of developing an infection:

  • cardiac devices, such as a pacemaker
  • prosthetic heart valves
  • catheters
  • prosthetic joints

Research also suggests that this type of infection accounts for most cases of neonatal sepsis, particularly with babies born prematurely. This may be due in part to them having an immature immune system.

S. epidermis has become methicillin-resistant due to the bacteria adapting and mutating. Reasons for why this may occur include the bacteria:

  • altering or reducing the way the antibiotic enters it
  • finding methods of removing the antibiotic after it enters the bacteria
  • changing or destroying the antibiotic using proteins and enzymes
  • altering the component of the bacteria that the antibiotic targets
  • bypassing the effects of the antibiotic by developing new cell processes

Antibiotic-resistant bacteria may also be able to share these resistance mechanisms with other bacteria that have not been exposed to antibiotic medications.

Diagnosis of MRSE usually begins with a medical history assessment and physical examination.

If a healthcare professional suspects MRSE, they may suggest a combination of bacterial and biochemical tests. This will usually involve obtaining samples from the site of infection, as well as blood and urine samples, and sending them to a laboratory for testing.

Once the laboratory technicians identify the bacteria, they can carry out antibiotic susceptibility testing (AST). Before the results of the AST return, healthcare professionals may assume that the bacteria is methicillin-resistant and prescribe alternative antibiotics in the meantime.

To identify antibiotic susceptibility, lab technicians can use equipment such as an automated phenotypic identification system.

These systems identify bacteria and antibiotic susceptibility by looking at certain biochemical reactions and nutrient usage from the microorganisms. This type of equipment not only identifies the type of infection but also highlights which antibiotics the bacteria may be resistant to.

Treatment of MRSE will typically involve using antibiotics that the infection is not resistant to. Some tests that lab technicians perform during diagnosis can help determine which antibiotics may work against the infection.

For example, vancomycin is a type of antibiotic that a doctor may prescribe to a person experiencing MRSE infection. This is because it is one of the best treatment choices for methicillin-resistant infections. A person would typically receive this via intravenous therapy.

However, in some cases, a doctor may administer a different type of antibiotic. The type of antibiotic will depend on several factors, including:

  • how the body responds to a specific antibiotic
  • how resistant the bacterium is
  • the kidney and liver function of the person experiencing the infection
  • a person’s blood count results
  • which other medications a person is taking, to avoid drug interactions

If the infection is due to a medical device, healthcare professionals will undertake an assessment to consider whether to remove the device.

MRSE is a strain of staph bacteria that is resistant to certain antibiotics, such as methicillin. This resistance can make it difficult to treat infections involving this bacterium.

People most at risk of developing an MRSE infection are typically those with an implanted medical device, such as a prosthetic joint or heart valve. The bacteria can enter the body through an opening in the skin and cause an infection in the bloodstream.

Diagnosis involves laboratory testing to identify the specific strain and its antibiotic resistance. Treatment options rely on alternative antibiotics that will have an effect on the strain of MRSE.