Increased Risk for MRSA Skin and Soft Tissue Infections Among HIV-Infected Persons

Nancy F. Crum-Cianflone, MD, MPH

Disclosures

January 15, 2010

Discussion

HIV-infected persons have an elevated risk for both MRSA colonization and infection.[1,2,3,4] Recent studies have suggested that patients with HIV have an 18 times higher rate of MRSA infections compared with that in the general population.[3,4] The incidence of MRSA infections among HIV-infected persons has been estimated as 9-12 cases per 1000 patient-years.[4,5]Clinical manifestations of MRSA infections among HIV-infected persons mirror those seen in the general population; most patients present with skin and soft-tissue infections (SSTIs) including furuncles, abscesses, and/or cellulitis.[3,6,7,8] Complicated disease also may occur, including necrotizing soft-tissue infections, fasciitis, bacteremia, and endocarditis.[9,10]

The reasons for the increased risk for MRSA infections among HIV patients is unknown, but may be related to an increased use of antibiotics in this population (eg, beta-lactam antibiotics), intravenous drug use, high-risk sexual behaviors, and poor immune status. The use of TMP-SMX for PCP prophylaxis has been associated with a reduced risk for MRSA infection.[1,3,11,12] Further prospective studies on the risk factors for MRSA infections among HIV-infected persons are needed.

In addition to the higher risk for MRSA infections, HIV-infected persons also appear to have a high risk for recurrent SSTIs after an initial MRSA infection.[5,7,13] Recent studies have demonstrated a remarkably high (41%-71%) rate of SSTI recurrence in HIV-infected adults initially presenting with MRSA, with a median time to recurrence of approximately 4 months.[5,13] One retrospective study found that higher HIV RNA levels and the lack of an initial performance of an incision and drainage procedure may be associated with recurrence.[5]

Another possible factor associated with recurrent infections is persistent colonization. In addition to nasal carriage, some studies have emphasized the importance of perineal MRSA carriage.[14] Studies examining novel carriage sites as well as the effectiveness of decolonization strategies and their impact on recurrent infections are needed.

Management of SSTIs due to MRSA includes incision and drainage of focal purulent collections. Routine culture with antibiotic susceptibility should be performed. Given the elevated rates of MRSA in the HIV population, empiric therapy with an anti-MRSA agent is likely warranted pending culture results, especially in complicated cases.

Initial antibiotic choices include doxycycline, minocycline, TMP-SMX, or linezolid for oral therapy; clindamycin can be used if shown to be susceptible by D-testing. Intravenous agents include vancomycin, daptomycin, linezolid, or tigecycline. Newer agents are on the horizon. Antimicrobial therapy should subsequently be modified based on antimicrobial susceptibility results. Recent reports have shown increasing rates of multidrug resistant community-acquired MRSA strains among HIV patients, which should be considered when selecting initial therapy, especially in complicated cases.[15]

Given the high risk for recurrence, HIV patients should be counseled to present early with any new skin lesion that may represent recurrent MRSA. Efforts to reduce colonization can be considered among HIV patients, although the efficacy of MRSA decolonization strategies in this setting remains unknown. If the patient has indications for TMP-SMX use (typically for PCP prophylaxis), this may provide an additional benefit in reducing MRSA colonization and infection.[11,12,16] Finally, although definitive studies are lacking, consideration for good HIV control (robust CD4+ counts with suppressed HIV RNA levels) may be helpful in reducing MRSA infections among HIV patients; however, prospective studies are needed.

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