Q: What can I do about MRSA infections?

Skin and soft tissue infections are frequently encountered in primary and urgent care settings. Many patients presenting with such an infection complain of a spider bite. In most cases, the “bite” is actually a cutaneous abscess caused by Staphylococcus aureus.1 Community-associated methicillin- resistant S aureus (CA-MRSA) has become an increasingly common cause of skin infections and abscesses.2,3

CA-MRSA involves unique bacterial strains and has several features that distinguish it from health care-associated (HA) MRSA. CA-MRSA is resistant primarily to beta-lactam antibiotics. Infection most often manifests as a minor skin abscess in a healthy person.1,4 HAMRSA, in contrast, is resistant to multiple antibiotics and is traditionally linked to surgery or hospitalization;1,5 however, recent studies have found CA-MRSA in the hospital setting.5 The increasing prevalence of skin infections caused by CA-MRSA is approaching epidemic levels in many areas.3

TRANSMISSION

CA-MRSA transmission between persons, likely by skin-to-skin contact, occurs between household contacts, sports team members, day-care center contacts, and people living in close quarters (such as soldiers or prison inmates).1,4,6 Recurrent cutaneous abscesses have been observed. However, discerning whether recurrences represent a new infection or colonization and self-inoculation is difficult.1,3

PREVENTION

Standard infection-control practices such as hand washing, covering draining lesions, and frequent laundering of linens and clothing are the mainstays of prevention.1 The importance of good personal hygiene and infection-control practices must be stressed to patients and parents. In addition, health care providers and sports team coaches should restrict an affected patient from activities, especially if the patient has a draining lesion that cannot be adequately covered.6

For patients with a history of recurrent CA-MRSA infections, decolonization methods that may lessen recurrences include using an OTC antibiotic cleanser with chlorhexidine for several days or applying mupirocin (Bactroban) ointment within the anterior nares and under the fingernails twice a day for about 7 days.1,7,8 Most techniques of decolonization are based on anecdotal evidence and studies of HA-MRSA; efficacy on CA-MRSA is unknown.1,3,7 In cases of recurrent infection, consultation with an infectious disease specialist may be beneficial.1

TREATMENT

Incision and drainage (I&D) remains the primary and most effective treatment for abscesses.1,4,8,9 Most small abscesses will resolve after I&D alone. However, antibiotic therapy is recommended when the abscess is 5 cm or larger, signs of systemic infection are present, significant overlying cellulitis is noted, or patient-specific risk factors (such as immune suppression or extremes of age) are present.1,3,9 Several antibiotics are recommended for outpatient treatment of CA-MRSA, including trimethoprimsulfamethoxazole (TMP/SMX; Bactrim, Septra), tetracyclines (doxycycline [Doryx, Monodox, Vibramycin] or minocycline [Dynacin, Minocin, Myrac]), and clindamycin (Cleocin).1,3,8

If TMP/SMX or doxycycline is used in patients with overlying cellulitis, adding a beta-lactam antibiotic for Streptococcus coverage is recommended. 1,2 Concern about using clindamycin is based on its potential for treatmentinduced antibiotic resistance.1,2,3

BOTTOM LINE

CA-MRSA is rapidly becoming the leading cause of skin and soft tissue abscesses in many areas. I&D remains the primary treatment for these abscesses, possibly with antibiotic therapy. Treatment for recurrent infections may include use of antibiotic cleansers and ointment. Prevention and infection-control practices must be stressed to help control the growing epidemic of CA-MRSA infections. JAAPA

Gregory Wanner is a physician assistant in the Department of Emergency Medicine, Underwood- Memorial Hospital, Woodbury, New Jersey. He has indicated no relationships to disclose relating to the content of this article.

Katie Iverson, PA-C, MPAS, department editor

REFERENCES

1. Gorwitz RJ, Jernigan DB, Powers JH, Jernigan JA. Strategies for clinical management of MRSA in the community: summary of an experts' meeting convened by the Centers for Disease Control and Prevention. CDC Web site. http://www.cdc.gov/ncidod/dhqp/pdf/ar/CAMRSA_ExpMtgStrategies.pdf. Accessed December 3, 2007.

2. Moran GJ, Krishnadasan A, Gorwitz RJ, et al. Methicillinresistant S. aureus infections among patients in the emergency department. N Engl J Med. 2006;355(7):666-674.

3. Daum RS. Clinical practice. Skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus. N Engl J Med. 2007;357(4):380-390.

4. Miller LG, Quan C, Shay A, et al. A prospective investigation of outcomes after hospital discharge for endemic, community-acquired methicillin-resistant and -susceptible Staphylococcus aureus skin infection. Clin Infect Dis. 2007;44(4):483-492.

5. Maree CL, Daum RS, Boyle-Vavra S, et al. Communityassociated methicillin-resistant Staphylococcus aureus isolates causing healthcare-associated infections. Emerg Infect Dis. 2007;13(2):236-242.

6. Methicillin-resistant Staphylococcus aureus infections among competitive sports participants—Colorado, Indiana, Pennsylvania, and Los Angeles County, 2000-2003. MMWR Morb Mortal Wkly Rep. 2003;52(33):793-795.

7. Simor AE, Phillips E, McGeer A, et al. Randomized controlled trial of chlorhexidine gluconate for washing, intranasal mupirocin, and rifampin and doxycycline versus no treatment for the eradication of methicillin-resistant Staphylococcus aureus colonization. Clin Infect Dis. 2007;44(2):178-185.

8. Gilbert DN, Moellering RC, Eliopoulos GM, Sande MA. The Sanford Guide to Antimicrobial Therapy 2007. 37th ed. Sperryville, VA: Antimicrobial Therapy; 2007:47-48,73.

9. Hankin A, Everett WW. Are antibiotics necessary after incision and drainage of a cutaneous abscess? Ann Emerg Med. 2007;50(1):49-51.

Patient Information

Q: What can I do about MRSA infections?

WHAT IS A SKIN ABSCESS?

An abscess is a skin infection that causes a pocket of pus under the skin. The skin is usually swollen, red, and painful. The pus may leak out of the abscess. Other names for an abscess are a boil or a furuncle.

WHAT CAUSES AN ABSCESS?

An abscess forms when bacteria get trapped inside your body. Bacteria are normally on the skin. A scratch or a cut is a break in your skin that can trap bacteria in your body. Most abscesses are not caused by spider bites. Most abscesses are caused by bacteria called
Staphylococcus aureus. This type of abscess
is sometimes called a staph (pronounced
staff) infection.

WHAT IS MRSA?

Methicillin-resistant Staphylococcus aureus, called MRSA, is a staph infection that cannot be cured with some antibiotics. Two types of MRSA are community-associated MRSA and health care-associated MRSA. Community-associated MRSA usually causes skin abscesses. Health care-associated MRSA is usually a more severe infection.

HOW CAN A PERSON BE INFECTED WITH MRSA?

You can be infected with MRSA if your skin comes in close contact with someone who has an abscess. You can be infected with MRSA if you share sports or gym equipment with someone who has an abscess. You can be infected with MRSA by living in a crowded place, such as a dorm or prison, with people who have the infection. You can be infected with MRSA if you do not wash your hands often and do not wash your body and clothes properly.

WHO CAN DEVELOP AN ABSCESS?

Anyone can get an abscess. You may be more likely to get an abscess if you have an illness that affects your immune system. You may be more likely to get an abscess if you have gotten an abscess in the past. Some people who are infected with MRSA may get many abscesses. Some people may get abscesses often.

HOW ARE ABSCESSES TREATED?

The best treatment is a procedure called incision and drainage. Your PA or doctor cuts open the abscess and drains out the pus. If the abscess is not ready to be drained, your PA or doctor may suggest using warm, moist compresses on the area to help draw out the infection. Most abscesses heal without taking any medication. But you may need an antibiotic if the abscess was large or you have an illness that affects your immune system. Make sure you finish the antibiotic. Do not share the antibiotic with someone else.

HOW CAN I PREVENT AN ABSCESS?

You can prevent an abscess by following some simple rules of cleanliness. Wash your hands frequently with soap and warm or hot water. Take a shower every day. Keep a draining wound covered with dry, clean bandages. Change the bandages often. Wear special gloves when washing the area or changing the bandages. Wash the area around the draining wounds with soap and water. Do not touch the pus from an abscess. The pus may contain bacteria that can make the infection grow. Wash all clothes, towels, and bed linens often with detergent and hot water. Use bleach, if possible. Dry all these items in the clothes dryer on the hot setting. Do not share razors, towels, clothes, or sports equipment.

Talk with your PA or doctor about prevention, especially if you or someone in your family develops abscesses often. Your health care provider may tell you to wash with an antibacterial soap that has chlorhexidine in it. Your health care provider may also tell you to apply an antibiotic ointment to the areas on your body where the bacteria can live. The soap and antibiotic ointment can eliminate some of the bacteria that will cause an abscess.

WHERE CAN I GET MORE INFORMATION?

You should talk to your PA or doctor about skin infections. You can get more information about communityassociated MRSA from the Internet. The Centers for Disease Control and Prevention has a Web site with a lot of information about MRSA and other skin infections. This Web site is www.cdc.gov. JAAPA