Methicillin-resistant Staphylococcus aureus (MRSA) is a type of staph bacteria resistant to many common antibiotics, including methicillin, oxacillin, penicillin, and amoxicillin, making its infections more challenging to treat. While many people carry MRSA harmlessly on their skin or in their nose, testing is important for determining its presence and guiding appropriate management, especially if an active infection is suspected.
When MRSA Testing is Recommended
MRSA testing may be recommended if you show symptoms of a possible infection. Common signs of a localized MRSA skin infection include a red, swollen, painful area that may look like a boil, pimple, or spider bite, sometimes filled with pus or fluid. If the infection spreads deeper into the body, symptoms can include fever, chills, cough, shortness of breath, chest pain, fatigue, or muscle and joint aches.
Risk factors for MRSA include recent hospitalization or surgery, having an invasive medical device like a catheter, residing in long-term care facilities, participating in contact sports, living in crowded conditions, or having a weakened immune system due to conditions like diabetes or HIV.
How MRSA is Diagnosed
MRSA is diagnosed by taking a sample from the affected area for laboratory analysis. Common methods include a nasal swab, where a healthcare provider gently rotates a swab inside each nostril. For skin infections, a wound culture involves swabbing the lesion or collecting fluid.
For widespread or serious infections, samples of blood, urine, or sputum (mucus coughed from the lungs) may be collected. These samples are then cultured on a special nutrient medium to encourage bacterial growth, typically taking 24 to 48 hours for results. Faster molecular tests, such as PCR, can detect MRSA DNA in nasal or wound samples within as little as five hours by identifying specific genetic markers, including the mecA gene which confers antibiotic resistance.
Where to Get Tested
If a MRSA infection is suspected, your primary care physician’s office is often the first place for testing. They assess symptoms, consider risk factors, and order diagnostic tests. Many clinics collect samples like nasal or wound swabs.
For immediate concerns like a painful skin infection or abscess, urgent care centers provide prompt evaluation and testing. Severe symptoms, such as high fever or difficulty breathing, indicating a deeper infection, warrant immediate medical attention and comprehensive testing at a hospital emergency room.
Specialized infectious disease clinics often manage complex cases of MRSA. They can also provide expert diagnosis and treatment.
Understanding Your Test Results
A positive MRSA test result indicates the presence of the bacteria in your body. It is important to distinguish between being a “carrier” (colonized) and having an active MRSA infection. If you are a carrier, MRSA is present on your skin or in your nose without causing symptoms, though you can still spread it. An active infection means the bacteria are causing symptoms like pus from a wound, fever, or pneumonia, and typically requires treatment.
For localized skin infections, treatment may involve draining the wound and topical or oral antibiotics. More severe infections, such as those in the bloodstream or lungs, often necessitate hospitalization and intravenous antibiotics.
For carriers, decolonization treatments like special nasal ointments or antibacterial washes may be recommended to reduce MRSA and minimize spread. Discussing results with a healthcare provider is important for personalized advice and follow-up.