Staphylococcus aureus is a common etiologic organism in soft tissue infections and may be found on the skin of nearly 20% of healthy people. Over the past several decades, infections with methicillin-resistant Staphylococcus aureus(MRSA) among hospitalized patients have become common. Recently, reports of MRSA infections acquired outside of the hospital setting (community-acquired MRSA or CA-MRSA) have increased nationally, including fatalities.
Effective February 13, 2008, severe S. aureus infections, resulting in death or admission to an intensive care unit of a person without history of hospitalization, surgery, dialysis, or residency in a long-term care facility in the past year, and without an indwelling catheter or percutaneous medical device the time of culture, are reportable in California. For more information about reporting, see the February 2008 issue of CD Connection.
This fact sheet is intended to improve awareness among health care providers regarding MRSA as an important emerging etiologic agent in community-acquired soft tissue infections.
Similar to the methicillin-sensitive S. aureus strains, MRSA can cause infections of the skin and soft tissue, bone, joints, blood, heart, and other parts of the body. However, community-acquired MRSA infections most commonly present as skin and soft tissue infections, including:
- Cellulitis - Inflammation of the skin
- Impetigo - Bullous (blistered) lesions or abraded skin with honey-colored crust
- Folliculitis - Infection of hair follicle (like a pimple)
- Furunculosis - Deeper infection below hair line
- Carbuncle - Multiple adjacent hair follicles and substructures are affected
- Abscess - Pus-filled mass below skin structures
- Infected laceration - Pre-existing cut that has become infected
Some MRSA skin lesions have been initially misdiagnosed as "spider bites"; verified spider bites are extremely rare and medically significant spiders are uncommon in Southern California.
Risk factors for CA-MRSA skin infection include crowded living conditions, frequent skin-to-skin contact (i.e., wrestling), lack of cleanliness, exposure to antibiotics, recurrent skin infections and/or non-intact skin, exposure to someone with MRSA, and exposure to jails or prisons.
The Centers for Disease Control and Prevention (CDC) provides detailed guidance to clinicians in the document, "Strategies for Clinical Management of MRSA in the Community: Summary of an Experts' Meeting Convened by the Centers for Disease Control and Prevention," available here. In addition, the CDC, American Medical Association (AMA), and Infectious Diseases Society of America (IDSA) have published an algorithm for outpatient management of skin and soft tissue infections in the era of community-associated MRSA, including options for antimicrobial treatment, available here. Major points from these documents are summarized below:
The first line of treatment for soft tissue infections is incision, drainage, and localized care. Incision and drainage constitutes a primary therapy for furuncles, other abscesses, and septic joints, and should be performed routinely. For small furuncles not amenable to incision and drainage or collection of material for culture, moist heat may be satisfactory to promote drainage. Often, antibiotic treatment is not necessary after adequate drainage. A follow-up plan should be discussed with the patient in case of failure to respond to drainage and progression of symptoms.
Clinicians are encouraged to collect specimens for culture and antimicrobial susceptibility testing from all patients with abscesses or purulent skin lesions, particularly those with severe local infections, systemic signs of infection, or history suggesting connection to a cluster or outbreak of infections among epidemiologically linked individuals. Culture and susceptibility results are useful both for management of individual patients and to help determine local prevalence of S. aureus susceptibility to beta-lactam and non-beta-lactam agents.
It is not necessary to routinely collect nasal cultures in all patients presenting with possible MRSA infection. In the absence of symptomatic infection, screening for MRSA colonization by culture is generally not useful unless for infection control or epidemiologic purposes.
Health care providers should continue prudent management of skin lesions and selective use of antibiotics, as inappropriate antibiotic use has been associated with the development of MRSA infection.
Empiric antibiotic treatment of skin and soft tissue infections is often initiated with antibiotics targeted against S. aureus, such as cephalexin (Keflex®) or dicloxacillin. However, all MRSA strains are resistant to these antibiotics and all other beta-lactam class antibiotics, all cephalosporins, and beta-lactamase inhibitor combinations. Empiric outpatient options for treatment of some CA-MRSA strains include clindamycin, doxycycline or minocycline, trimethoprim-sulfamethoxazole (Bactrim or Septra), or linezolid, but it is important to be familiar with the susceptibility patterns of CA-MRSA strains in your community. In addition, each class of antibiotics has specific considerations and precautions that may limit their use; these are included in the CDC/AMA/IDSA summary of options available here. Clinicians should consult product labeling for a complete list of potential adverse effects associated with a particular agent.
If the patient is found to have a MRSA skin infection and antibiotics are indicated, use culture and susceptibility testing results to select an antibiotic to which the organism is susceptible. Patients with signs and symptoms of severe illness should be treated as inpatients.
Reviewing good hygiene practices and wound care with patients including diligent handwashing, washing of contaminated items with warm water and soap, and proper disposal of contaminated bandages and wound coverings is essential in prevention of transmission of MRSA among contacts. Patients who cannot maintain adequate hygiene and keep wounds covered with clean, dry bandages should be excluded from activities where close contact with other individuals occurs, such as daycare or athletic practice, until their wounds are healed.
Decolonization regimens may be helpful in preventing recurrent infections in an individual patient or members of a household but optimal regimens for use in community settings have not been established. Some regimens have included nasal mupirocin (Bactroban) and/or antiseptic body washes (e.g., chlorhexidine) for patients with recurrent MRSA infections and their close contacts. However, decolonization should be considered only after the active infection has been treated and standard prevention, wound care, and hygiene measures have been reinforced. Resistance to mupirocin has been reported, so judicious use is necessary. Consultation with an infectious disease specialist should be considered in patients regarding use of decolonization.
Note: The use of product names is not meant to imply endorsement of specific products by the Orange County Health Care Agency.
Skin infections with MRSA are transmitted by close skin-to-skin contact with an infected person or by contact with objects or surfaces contaminated with MRSA.
To help prevent the spread of MRSA in a health care setting:
Between patients, wash hands regularly with antimicrobial soap and warm water. When hands are not visibly soiled, alcohol-based hand sanitizer use is effective.
Wear gloves when managing wounds. After removing gloves, wash hands with soap and warm water, or use alcohol-based hand sanitizer.
Carefully dispose of dressings and other materials that come into contact with blood, nasal discharge, urine, or pus from patients infected with MRSA.
Clean surfaces in exam rooms with commercial disinfectant or a 1:100 solution of diluted bleach (1 tablespoon bleach in 1 quart of water). The United States Environmental Protection Agency (EPA) has a list of specific products registered as effective against MRSA, available here.
Launder any linens that come into patient contact in hot water (>160°F) and bleach. The heat of commercial dryers improves bacterial killing.
Many experts recommend Contact Precautions for patients with MRSA. Refer to your hospital's or clinic's infection control policies for the procedure in your facility. The following Centers for Disease Control and Prevention (CDC) websites provide additional information regarding hand hygiene and environmental control in the health care setting:
Hand Hygiene in Healthcare Settings:
Management of Multidrug-Resistant Organisms in Healthcare Settings, 2006.
Key Prevention Messages for Patients with Skin and Soft Tissue Infections and their Close Contacts
Keep wounds that are draining covered with clean, dry, bandages.
Clean hands regularly with soap and water or alcohol-based hand gel (if hands are not visibly soiled). Always clean hands immediately after touching infected skin or any item that has come in direct contact with a draining wound.
Maintain good general hygiene with regular bathing.
Do not share items that may become contaminated with wound drainage, such as towels, clothing, bedding, bar soap, razors, and athletic equipment that touches the skin.
Launder clothing that has come in contact with wound drainage after each use and dry thoroughly.
If you are not able to keep your wound covered with a clean, dry bandage at all times, do not participate in activities where you have skin to skin contact with other persons (such as athletic activities) until your wound is healed.
Clean equipment and other environmental surfaces with which multiple individuals have bare skin contact with a commercial disinfectant that specifies Staphylococcus aureus on the product label or a 1:100 dilution of household bleach (1 tablespoon bleach in 1 quart of water) and is suitable for the type of surface being cleaned. Always follow the product label instructions.
Clusters of community-acquired MRSA have been reported in prisons and jails, daycares, athletic teams, and among men who have sex with men. Health care providers should report to the County of Orange Health Care Agency Epidemiology program at 714-834-8180 any unusual clusters of patients with MRSA infections. Health care providers should track the characteristics of skin lesions seen in their own practices and note patterns of antibiotic resistance, which can help identify unusual trends and guide appropriate treatment decisions.
If you have any additional questions, please contact the Epidemiology & Assessment Unit, County of Orange Health Care Agency by telephone: (714) 834-8180, or by email: EPI@ochca.com.
Resources for Physicians and Other Health Care Providers
Resources for Patients