Methicillin-resistant Staphylococcus aureus (MRSA) is a type of bacteria resistant to several common antibiotics, including methicillin and penicillin-related drugs. This microorganism frequently resides harmlessly on the skin and inside the nose of many healthy individuals. Given its reputation as a difficult-to-treat microbe, this article examines the nature of MRSA, its presence in the nasal cavity, and the steps taken to manage it.
Staph vs. MRSA
Staphylococcus aureus, often called Staph, is the parent bacterium of MRSA. This bacterium is extremely common and is considered a normal part of the human microbiome, living on the skin and in the nasal passages of approximately one-third of the population. For the majority of these carriers, Methicillin-Sensitive S. aureus (MSSA) never causes illness. If an infection does occur, it is typically treatable with standard antibiotics.
MRSA is a strain of S. aureus that has acquired genetic material making it resistant to beta-lactam antibiotics, such as methicillin, amoxicillin, and penicillin. This resistance means that if the bacteria causes an infection, the initial line of antibiotic treatment will not be effective. Treatment options for MRSA are more limited and challenging.
Colonization vs. Active Infection
The distinction between colonization and active infection is important for understanding nasal MRSA. Colonization refers to the presence of the bacteria living on the body, such as in the nose or on the skin, without causing illness or symptoms. While about one-third of people carry S. aureus, the rate of MRSA nasal carriage is much lower, generally estimated to be between 1% and 10% of the general population.
For most colonized individuals, the MRSA bacteria remains dormant. Active infection occurs when the bacteria penetrates the body, often through a break in the skin, causing a disease state. This can manifest as a skin infection, such as a boil or abscess, or in serious cases, lead to pneumonia or a bloodstream infection.
How MRSA Spreads and Who Is At Risk
MRSA is primarily transmitted through direct physical contact with a colonized or infected person, or by touching contaminated objects and surfaces. The bacteria transfers easily from the nasal passage to the hands, and then to other people or items. The risk of developing an active infection is highest in specific environments and populations.
Healthcare-Associated MRSA (HA-MRSA) affects individuals in healthcare settings. This includes patients hospitalized for extended periods, those residing in long-term care facilities, and people with invasive medical devices like catheters or central lines. These factors increase vulnerability due to weakened immune systems and pathways for bacteria to enter the body. Community-Associated MRSA (CA-MRSA) affects healthy people outside of a medical facility, often spreading in crowded or close-contact environments such as locker rooms, military barracks, and among contact sports participants.
Managing Nasal Carriage
Simple hygiene practices are the first line of defense for individuals confirmed to be carrying MRSA in their nose. This includes consistent and thorough handwashing with soap and water, especially after touching the nose. Any cuts, scrapes, or wounds on the skin should be kept clean and covered with bandages until fully healed.
Decolonization treatment is not routinely recommended for all carriers. This treatment is typically reserved for high-risk patients, such as those scheduled for major surgery or those with recurrent MRSA infections. The standard regimen involves a five-day course using an antibiotic nasal ointment, such as mupirocin, applied inside the nostrils twice daily. This is often combined with an antiseptic body wash, like chlorhexidine, to reduce bacteria on the skin. Any decision regarding testing or decolonization should be made in consultation with a healthcare provider.