Susceptibility of Staphylococcus aureus to topical agents in the United States: a sentinel study.
BACKGROUND
Mupirocin has been used topically for treating skin and skin structure infections and for nasal decolonization before surgical interventions. Pleuromutilin compounds, including retapamulin, provide similar treatment/interventional options. Rates of resistance of Staphylococcus aureus to mupirocin and other agents used to treat skin and skin structure infections vary between countries and medical centers, including those in the United States. These resistance rates may be associated with higher usage and/or improper epidemiologic practices.


OBJECTIVE
This study aimed to determine rates of resistance to topical and other class agents against S aureus isolates collected from SSSIs.


METHODS
Isolates were obtained from outpatients at 6 US dermatology centers in 5 states. Demographic data were collected from medical records, and each patient completed a study questionnaire on recent history of skin infections, antibiotic use, and hospitalization. Each isolate was tested against cephalothin, clindamycin, erythromycin, gentamicin, mupirocin, tetracycline, retapamulin, and trimethoprim/sulfamethoxazole.


RESULTS
Although methicillin-resistance rates varied between centers (range, 15.8%-35.5%), macrolide resistance was ~50% at all of the sites in this study. Mupirocin-resistant isolates were observed much more frequently from 1 center (33.9%), and nearly all demonstrated high-level resistance. Only 1 retapamulin-resistant isolate (0.5%) was observed, with a minimum inhibitory concentration of 16 µg/mL. The other agents had relatively low resistance rates, which varied between centers and were dependent on susceptibility to methicillin.


CONCLUSIONS
Although the rate of mupirocin-resistant S aureus isolates collected in this investigation was >10%, retapamulin resistance was infrequent. Surveillance of topical agents to determine resistance rates against targeted bacteria is necessary.
International Health Management Associates, Inc, Schaumburg, Illinois. Electronic address: xxx@ihmainc.com.
Douglas J
DJ
Biedenbach
International Health Management Associates, Inc, Schaumburg, Illinois.
Samuel K
SK
Bouchillon
International Health Management Associates, Inc, Schaumburg, Illinois.
Seth A
SA
Johnson
International Health Management Associates, Inc, Schaumburg, Illinois.
Daryl J
DJ
Hoban
International Health Management Associates, Inc, Schaumburg, Illinois.
Meredith
M
Hackel
D000287:Administration, Topical; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000627:therapeutic use; D002981:Clindamycin; D004224:Diterpenes; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D016712:Mupirocin / Q000494:pharmacology* / Q000627:therapeutic use; D013207:Staphylococcal Skin Infections / Q000188:drug therapy* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013530:Surgical Wound Infection / Q000517:prevention & control; D014481:United States
D000900:Anti-Bacterial Agents; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004224:Diterpenes; D002981:Clindamycin; C508887:retapamulin; D016712:Mupirocin
Staphylococcus aureus; bacterial resistance; mupirocin; retapamulin; skin and skin structure infections