A positive Methicillin-resistant Staphylococcus aureus (MRSA) nasal swab result means the bacteria is present in the nasal cavity. MRSA is a type of staph bacteria resistant to several common antibiotics, including methicillin, penicillin, and amoxicillin. The nasal swab is a screening tool frequently used in healthcare settings, involving the collection of a sample from inside the nostril. The primary purpose of this quick test is to check for the presence of the organism, not to diagnose an active illness.
Colonization Versus Active Infection
A positive nasal swab almost always indicates colonization, where the bacteria are present on the body without causing illness. Many healthy people carry Staphylococcus aureus bacteria, including the MRSA strain, on their skin or in their nose without experiencing problems. In this state, the bacteria are simply coexisting with the host and are not actively invading tissues or causing disease. This carriage is asymptomatic, meaning the person feels well and has no fever, redness, or pus formation.
An active infection occurs when MRSA bacteria breach the body’s defenses and begin to multiply inside tissues. This invasion causes an immune system reaction, leading to symptoms like redness, swelling, pain, warmth at the site of a wound, or a general fever. Common MRSA infections often resemble pus-filled boils or abscesses on the skin. The positive nasal swab result, on its own, identifies the person as a carrier, but does not confirm an active MRSA infection.
Colonization is a strong risk factor for developing an infection later, especially if the carrier undergoes surgery or has a weakened immune system. The presence of MRSA in the nose increases the likelihood of the bacteria traveling to a site in the body where it can cause harm, such as after a hospital stay or surgical procedure. Therefore, the nasal swab acts as a predictive measure to identify individuals who may require preventative action.
Decolonization Protocols and Treatment
The standard medical response to confirmed MRSA colonization is a decolonization protocol aimed at reducing the number of bacteria on the skin and in the nose. These protocols involve a combination of topical antimicrobial treatments applied for a set period. A common regimen involves applying a specialized antibiotic ointment, such as mupirocin, inside the nostrils twice daily for five days. This nasal ointment targets the bacteria, as the nasal passages are a frequent reservoir for MRSA carriage.
In addition to the nasal treatment, a specialized antiseptic body wash is often prescribed for daily use during the same five-day period. These washes frequently contain chlorhexidine gluconate (CHG) and are used to cleanse the entire body, paying particular attention to skin folds like the groin and armpits. This dual approach aims to significantly reduce the overall bacterial load on the body’s surface. Prolonged or repeated use of these products is avoided to prevent the bacteria from developing resistance.
Following the completion of the decolonization treatment, follow-up testing, often another nasal swab, is sometimes performed to confirm the absence of MRSA bacteria. Decolonization does not offer permanent protection, and recolonization can occur over time. The goal of the treatment is primarily to reduce the risk of infection during a vulnerable period, such as before a planned surgical procedure. A healthcare provider manages the entire process and determines the necessity and specifics of the protocol.
Reducing Transmission Risk
A primary reason for treating MRSA colonization is to prevent the carrier from transmitting the bacteria to others, particularly in healthcare settings or to vulnerable family members. MRSA is spread most commonly through direct skin-to-skin contact or by touching contaminated surfaces. Meticulous hand hygiene is the most effective measure for reducing transmission, requiring frequent washing with soap and water or the use of an alcohol-based hand sanitizer. This practice is essential after touching the nose, wounds, or before preparing food.
Practical steps in the home environment can minimize the risk of spread to family members.
Home Hygiene Practices
- Personal items that touch the skin, such as towels, washcloths, razors, and bed linen, should not be shared.
- Wounds, cuts, and abrasions should always be kept clean and covered with a dry, intact bandage until they are fully healed.
- Clothes, towels, and bedding used by a colonized person should be washed regularly in the hottest water suitable for the fabric.
Individuals who are known to be colonized should inform their healthcare providers, especially before any invasive medical procedure, such as surgery or the insertion of a catheter. This allows the medical team to implement additional infection control measures, potentially including the pre-procedure decolonization protocol. Household cleanliness, particularly of frequently touched surfaces, also plays a role in reducing the presence of the organism in the environment.