What Infections Does Staphylococcus Epidermidis Cause?

Staphylococcus epidermidis is a bacterium that lives on human skin, and it is usually harmless there. When it gets inside the body, though, it can cause infections — most often on medical devices like catheters, artificial joints, and heart valves. It is one of the most common causes of infections tied to hospital care.

What Is Staphylococcus Epidermidis?

Staphylococcus epidermidis is a gram-positive bacterium and a member of the coagulase-negative staphylococci group. It is one of the most abundant bacteria on human skin, found in nearly every person. It typically colonizes the skin, nose, and mucous membranes without causing any harm.

On intact skin, it acts as part of the normal microbiome. It can even help defend against more dangerous bacteria by competing for space and nutrients. The problem starts when the skin barrier breaks or when a medical device gives the bacteria a way inside.

This bacterium is different from Staphylococcus aureus. S. aureus is more aggressive and produces coagulase, an enzyme that helps it clot blood and evade the immune system. S. epidermidis does not produce coagulase. That difference matters because it shapes how each bacterium causes disease and how doctors treat it.

What Infections Does Staphylococcus Epidermidis Cause?

Staphylococcus epidermidis causes infections almost exclusively in people with a foreign body in place or a compromised immune system. The bacterium forms a slimy layer called a biofilm on the surface of medical devices, which protects it from antibiotics and from the body’s immune defenses.

The most common infections linked to S. epidermidis include:

• Catheter-related bloodstream infections — especially with central venous catheters, which are placed in large veins for long-term use
• Prosthetic joint infections — after hip or knee replacement surgery
• Prosthetic heart valve infections — also called prosthetic valve endocarditis
• Infections of cerebrospinal fluid shunts — devices placed to drain fluid from the brain
• Peritoneal dialysis catheter infections — used by people with kidney failure
• Infections of pacemakers and implanted defibrillators
• Surgical site infections — particularly after procedures involving implants
• Neonatal infections — in premature infants with central lines or other invasive devices

In people with severely weakened immune systems — such as those receiving chemotherapy or organ transplants — S. epidermidis can cause bloodstream infections even without an obvious device. These cases are less common but can be serious.

Why Does S. epidermidis Cause Infections on Medical Devices?

Medical devices provide a surface where S. epidermidis can attach and build a biofilm. A biofilm is a community of bacteria encased in a self-produced matrix of sugars and proteins. Once formed, it acts like a shield.

The biofilm makes the bacteria far more resistant to antibiotics than if they were floating freely. It also hides them from immune cells. This is why device-related infections are so difficult to treat and often require removing the device entirely.

The bacteria usually get onto the device during insertion, from the patient’s own skin. That is why careful skin preparation before surgery or catheter placement matters. Later contamination can also occur if the device site is not kept clean.

One important detail: S. epidermidis is not usually spread from person to person in the way that a cold or flu virus is. The source is almost always the patient’s own skin flora or the hospital environment during a procedure.

Who Is Most at Risk?

The people at highest risk are those with a medical device in place or a weakened immune system. Specific groups include:

• Hospital patients with central venous catheters or other long-term lines
• People who have had joint replacement, heart valve replacement, or other implant surgery
• Premature infants in neonatal intensive care units
• Patients receiving chemotherapy, corticosteroids, or immunosuppressive drugs
• People on long-term peritoneal dialysis
• Patients with cerebrospinal fluid shunts

Healthy people without devices or immune suppression rarely get infections from S. epidermidis. Even when the bacterium enters the bloodstream briefly — for example, after brushing teeth — the immune system usually clears it without symptoms.

What Are the Symptoms?

Symptoms depend on where the infection is. They are often subtle at first, which can delay diagnosis.

For a bloodstream infection from a catheter, symptoms may include fever, chills, and a general feeling of being unwell. The area around the catheter site might be red or tender, but often it looks normal.

For a prosthetic joint infection, symptoms can include pain that was previously improving, swelling, warmth, and reduced ability to move the joint. Sometimes the joint simply becomes painful months after surgery, without obvious redness.

For a heart valve infection, symptoms may include fever, fatigue, a new heart murmur, or signs of heart failure. These infections can be life-threatening if not treated.

In premature infants, symptoms can be vague — poor feeding, temperature instability, or breathing problems. Doctors often suspect infection based on these signs rather than specific complaints.

How Is It Diagnosed?

Diagnosis usually requires growing the bacterium from a sample. Blood cultures are used for suspected bloodstream infections. Fluid or tissue from around a device may be cultured for joint or surgical site infections.

A key challenge is distinguishing true infection from contamination. Because S. epidermidis is everywhere on the skin, it can easily contaminate a blood culture during collection. Doctors often require multiple positive cultures or other evidence before confirming a bloodstream infection.

For device-related infections, imaging tests like ultrasound, CT scans, or MRI may help show fluid collection or inflammation around the device. In some cases, the device itself is removed and cultured directly.

How Are These Infections Treated?

Treatment almost always involves antibiotics and, in many cases, removal of the infected device. This is because biofilms make it nearly impossible to clear the infection while the device remains in place.

Antibiotic choice depends on susceptibility testing. Many S. epidermidis strains are resistant to multiple antibiotics, including methicillin and sometimes vancomycin. This resistance is a major reason treatment is challenging.

For catheter-related infections, removing the catheter is often the first step. For prosthetic joint infections, surgery may be needed to wash out the joint or replace the implant. For heart valve infections, surgery to replace the valve is sometimes required.

Antibiotic treatment duration varies. It can range from a few days to several weeks, depending on the site and severity. No single duration fits all cases, and doctors tailor treatment to the individual.

Some clinicians use antibiotic lock therapy for catheters — instilling a high concentration of antibiotics into the catheter lumen and leaving it there. This approach is used in some cases but is not appropriate for all patients or all types of infections.

Can It Be Prevented?

Prevention focuses on reducing the chance that S. epidermidis gets onto a device or into a wound. Hospitals use several strategies:

• Careful skin cleaning before surgery or catheter insertion
• Using sterile technique when placing devices
• Antibiotic-coated catheters in some high-risk situations
• Removing devices as soon as they are no longer needed
• Keeping the device site clean and dry

For patients, the most important steps are following care instructions for any device and reporting signs of infection — like fever, redness, or pain — to a doctor promptly.

There is no vaccine for S. epidermidis. And because the bacterium is part of normal skin flora, eliminating it from the body is neither possible nor desirable.

Is Staphylococcus Epidermidis Contagious?

S. epidermidis is not contagious in the usual sense. It is already on almost everyone’s skin. You cannot catch it from someone else the way you catch a cold.

In hospitals, however, the bacterium can spread from patient to patient via contaminated hands or equipment. That is why hand hygiene is so important in healthcare settings. But the infection itself arises when the bacterium enters a normally sterile site, not from person-to-person transmission in everyday life.