The Centers for Disease Control (CDC) have documented studies on methicillin-resistant Staphlococcus aureus (MRSA), an organism that is not new to healthcare professionals but one that is continuously evolving. In 1972 only 2% of S. aureus were resistant to most β-lactam antibiotics (eg, methicillin, oxacillin, penicillin, amoxicillin), but by 2004, 63% exhibited resistance. The CDC issued a press release in October, 2007 establishing just how many infections and deaths resulted from MRSA during 2005; more than 94,000 life-threatening infections and almost 19,000 deaths occurred in the United States. Most (ie, 85%) of the infections were associated with healthcare settings, occurring after medical procedures or stays in hospitals or long-term care facilities within the previous year. Only 15% were considered community-associated (without documented healthcare exposure). Invasive MRSA infections were highest among people 65 years or older, and black people were affected at twice the rate of white people. Future statistics will be measured against these numbers to judge the success of efforts to control this serious infectious disease. Controlling MRSA should be a greater priority for healthcare; 100% compliance with CDC Infection Control Guidelines gives the best chance of succeeding against MRSA.1
S. aureus, or “staph”, is a type of bacteria that is commonly present, but does not cause disease, in 25% to 30% of the population’s noses and skin. S. aureus is one of the most common causes of skin infections in the U.S. About 1% of the population is colonized with MRSA. Both S. aureus and MRSA infections most commonly present as mild skin infections (eg, pimples, boils), but can also cause more severe, locally destructive or systemic infections involving surgical sites, blood, lungs, and bones. Minor staph infections can usually be treated by incision and drainage with or without antibiotics, while some strains of MRSA produce a toxin (ie, Panton Valentine leukocidin, or PVL) that can cause pneumonia and kill individuals with the disease within 72 hours. S. aureus can also lead to inflammation, toxic-shock syndrome, and meningitis. Resistant infections require the use of alternative medications, often with lower efficacy and more side effects.
S. Aureus is a biofilm-forming organism, with a protective polysaccharide matrix that protects the bacteria and makes treatment more difficult. Perhaps one of the most promising areas of related research is the study of biofilms and how to manipulate them.
Staph infections, including MRSA, are more frequent among medical patients with weakened immune systems. Hospital-associated infections include surgical wound infections, urinary tract infections, bloodstream infections, and pneumonia.
Community-associated MRSA (CA-MRSA) infects those who have not had medical treatment or stayed in medical facilities in the past year, and usually occurs in otherwise healthy individuals. Clusters of CA-MRSA have occurred in athletes, military recruits, children, Pacific Islanders, Alaskan Natives, Native Americans, men who have sex with men, and prisoners.1 CA-MRSA has unique microbiologic and genetic properties, or virulence factors, such as production of specific toxins that may facilitate rapid spread and infection. At least three strains are known to exist in the U.S. Transmission is associated with close skin-to-skin contact, skin openings (eg, cuts, abrasions), contaminated items and surfaces, crowded living conditions and poor hygiene. Community-associated MRSA often presents as a boil or abscess that is red, swollen, and painful with pustular drainage. If it becomes systemic, serious blood stream infections may lead to shortness of breath, fever, chills, pneumonia, and death. MRSA is often undiagnosed in the early stages due to unfamiliarity with the typical symptom: a high fever following a skin infection. Professional athletes have been stricken with CA-MRSA, transmitted by synthetic grass, towels, locker room surfaces, and gym equipment. In the community, the most frequent mode of transmission is via physical contact with contaminated individuals or by touching contaminated surfaces or items; crowded conditions also provide transmission routes (Tables 1 and 2).
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Diagnosis of MRSA is achieved by culturing tissue or drainage from the site and treatment is determined by the susceptibility profile of the organism. Unfortunately, culturing takes time, so heightened awareness of signs and symptoms is important. Patients often vaguely remember a “spider bite” and development of a fever. In some states, MRSA is a reportable disease.
If MRSA is suspected, seek medical attention immediately. Local treatment such as drainage should be provided by medical professionals. If antibiotics are prescribed, follow directions exactly and complete the full regimen to avoid further microbial resistance. If the infection does not improve or heal, visit the doctor again immediately.
In dental and medical settings, compliance with infection control protocol, especially hand asepsis, is the best hope of controlling MRSA and other resistant organisms. In the community, the following practices are most important to avoid exposure to MRSA:2
- Practice good hand hygiene;
- Keep cuts and scrapes clean and covered with a bandage until healed;
- Avoid contact with other people’s wounds or bandages;
- Avoid sharing personal items (eg, towels, razors, clothes, jewelry, personal protective equipment, cosmetics, hair clips, hairbrushes); and
- Wash soiled sheets, towels and clothes in hot water with bleach and dry in a hot dryer.
To prevent spreading MRSA to someone else:3
- Cover your wound with clean dry bandages. Bandages may be discarded in regular trash;
- Wash hands thoroughly and frequently with warm water and soap. In the absence of physical contamination, alcohol sanitizers are appropriate;
- Do not share personal items that may have been contaminated with MRSA;
- Talk to your doctor: advise and be advised of risks;
- Wash all clothes, sheets, towels in hot water with detergent, and dry in a hot dryer. Perform hand hygiene after handling soiled or contaminated items;
- Clean environmental surfaces and items with a detergent-based cleaner or Environmental Protection Agency (EPA) registered disinfectant effective against MRSA, following label instructions. A list of EPA products effective against MRSA can be found at: http://epa.gov/oppad001/chemregindex.htm;4 and
- Do not use surface disinfectants to treat skin infections.
Methicillin-resistant S. aureus is a bacterium resistant to drugs used to treat infections; surface disinfectants, environmental barriers, hand hygiene practices and products, instrument sterilization, aseptic techniques, and the use of personal protective equipment can defeat this organism before it enters the body. Dental professionals should be knowledgeable about the organism, how it is transmitted, implications of infection, and how to prevent transmission. This understanding should also be shared with patients and family; and facilities should be in place in dental settings to practice effective protection and include patients in the program to defeat the spread of MRSA.
*OSAP member and consultant in infection control
- Centers for Disease Control and Prevention. www.cdc.gov. Accessed 12/17/10.
- The Organization for Safety and Asepsis Procedures. www.osap.org. Accessed 12//17/10.
- United States National Library of Medicine: National Institutes of Health. www.nlm.nih.gov. Accessed 12/17/10.
- United States Environmental Protection Agency. Selected EPA-registered Disinfectants. http://epa.gov/oppad001/chemregindex.htm. Accessed 12/17/10.