Community - Acquired Methicillin - Resistant Staphylococcus aureus Infection

Figure

A 14-month-old infant was brought by his mother for evaluation of fever (temperature, 39.4C [103F]) and a tender, indurated, warm area with surrounding edema and a centrally located papule in the left groin. The mother had noticed the lesion earlier that day and thought it had increased in size. The infant had no history of significant medical problems.

There was no drainage from the lesion. Two more small papules were noted on the buttocks. Physical findings were otherwise unremarkable.

Wound culture was positive for methicillin-resistant Staphylococcus aureus (MRSA). Initial treatment with intravenous vancomycin was switched to intravenous clindamycin after culture results showed MRSA. The patient's symptoms resolved after 2 days of treatment.

Community-acquired MRSA (CA-MRSA) is currently the most common cause of skin and soft tissue infections in the United States.¹The clinical features of MRSA cellulitis include erythema, swelling, and tenderness with papules that may develop into abscesses. Children and day-care workers are among several groups that are considered at high risk for MRSA infections.²

The strains that cause CAMRSA and hospital-acquired MRSA (HA-MRSA) infections are distinct.¹ CA-MRSA strains are more easily transmitted than HA-MRSA strains. The increased virulence of CA-MRSA strains is attributed to certain toxins, particularly Panton-Valentine leukocidin, which is associated with increased invasiveness and abscess formation. ³ However, there is no significant difference in the clinical presentation between the 2 types of MRSA infections.

Purulent skin and soft tissue infections without systemic signs, such as fever, are managed with incision and drainage with or without oral antibiotics.³ Many clinicians recommend bathing affected children in water that contains small amounts of chlorine bleach ("bleach baths").

The most popular options for outpatient antibiotic therapy are clindamycin and trimethoprim/ sulfamethoxazole. Other choices may include linezolid or a tetracycline, although these are often not advised in children younger than 9 years because of the possibility of tooth discoloration. Options for inpatient parenteral antibiotics include vancomycin, clindamycin, and trimethoprim/sulfamethoxazole.³ CA-MRSA strains are usually susceptible to clindamycin and more susceptible to non-?-lactam antibiotics than HA-MRSA strains.³

Preventive measures include good hand washing, thorough draining and cleaning of wounds, washing clothes after contact with contaminated skin, and avoiding sharing items with sick contacts.

References:

• Klevens RM, Morrison MA, Nadle J, et al. Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA. 2007;298: 1763-1771.

• Kaplan SL. Community-acquired methicillin-resistant Staphylococcus aureus infections in children. Semin Pediatr Infect Dis. 2006;17:113-119.

• Daum RS. Clinical practice. Skin and soft-tissue infections caused by methicillin-resistant Staphylococcus aureus [published correction appears in N Engl J Med. 2007;357:1357]. N Engl J Med. 2007; 357:380-390.