Staph vs. MRSA: What’s the Difference?

The short answer

MRSA is staph. Both are the same kind of bacteria, Staphylococcus aureus. MRSA stands for methicillin-resistant Staphylococcus aureus, and it is a type of staph that can resist several antibiotics.¹

Methicillin is an antibiotic, and the name tells you what makes MRSA different: this strain isn’t stopped by methicillin and several related medicines.

So the difference is not how it looks, where it lives or how it spreads. The difference is which medicines work against it. Staph that responds to the usual antibiotics is sometimes called MSSA, for methicillin-susceptible.

Side by side

• The germ: Both are Staphylococcus aureus.
• Who carries it: About 1 in 3 people for staph, about 2 in 100 for MRSA.²
• How it spreads: The same ways, mainly through skin contact and shared items.¹
• What an infection looks like: The same.¹
• How it is confirmed: A lab test for both.⁵
• Treatment: Different antibiotic choices, because MRSA resists several common ones.¹

How common each one is, and who is at risk

Staph is very common. About one in three people carry it in their nose, usually without any illness.² MRSA is much less common: about two in every 100 people carry it.²

Carrying either one is called being colonized. It doesn’t mean you are sick. For most people, most of the time, carried staph causes no harm.³ To learn more, read Staph in Your Nose.

The risk factors for staph and MRSA overlap a lot. The CDC lists these groups as more likely to get a staph infection:³

• People with long-term conditions such as diabetes, cancer or vascular disease
• People who inject drugs
• Hospital patients, especially in intensive care
• People who recently had surgery or have medical devices such as catheters

MRSA also spreads in everyday settings, among athletes who share towels or razors, children in day care and military members.⁶

Do they look different?

No. Staph and MRSA skin infections look the same. Most show up as a bump or infected area on the skin that may be:¹

• Red
• Swollen
• Painful
• Warm to the touch
• Full of pus or other drainage
• Accompanied by a fever

People sometimes mistake these infections for a spider bite. The CDC notes that unless you actually saw the spider, it probably isn’t one.¹ You can’t tell by looking whether an infection is MRSA.¹ Both can also look like a pimple, a boil or another common skin problem.³

What “resistant” really means

“Resistant” describes the germ, not the person. It means certain antibiotics no longer stop that strain from growing.

Methicillin was introduced in the UK in 1959, and MRSA was detected soon after.⁴ A 2017 genetic study suggests the resistance actually arose in the mid-1940s, more than a decade before methicillin existed, likely driven by the heavy use of penicillin at the time.⁴ It is a good reminder of why doctors choose antibiotics carefully today.

For you, the practical upshot is simple. If you are prescribed an antibiotic for any infection, take it exactly as directed, and don’t save leftovers or share them with anyone else.

Is one more serious than the other?

Not always. The CDC is clear that any staph infection can be dangerous, even if it is not resistant to antibiotics.³ What MRSA changes is the treatment plan, because some usual choices won’t work. Either kind can spread from the skin to the bones, joints, blood or organs if it gets deeper into the body.⁶

That is why testing matters. A doctor can take a sample from a wound, the nose, blood or urine, depending on where the infection is.⁵ Standard lab cultures take about 24 to 48 hours, and the result helps your doctor choose the right treatment.⁵ For a skin infection that hasn’t spread, draining it in the office may be the only treatment needed.⁶ That is a job for a doctor, never something to try at home.

When to see a doctor

Whether it turns out to be staph or MRSA, the signs to act on are the same. Contact a doctor if you have:

• A skin infection with a fever¹
• A sore that doesn’t improve within 48 hours¹
• Redness that is spreading or pain that keeps getting worse
• A wound that is getting worse instead of healing⁶

Get urgent care or call 911 for a fever with fast-spreading redness, confusion, trouble breathing, or feeling very unwell.

Until you can be seen, the CDC suggests covering the area with clean, dry bandages, not picking at or popping the sore, and cleaning your hands often.¹

The habits that lower your risk are the same for both: wash your hands often, keep cuts clean and covered, and don’t share towels or razors.^1,3 For a deeper look, read What Is MRSA?