Binh An Diep, PhD; Henry F. Chambers, MD; Christopher J. Graber, MD, MPH; John D. Szumowski, MD, MPH; Loren G. Miller, MD, MPH; Linda L. Han, MD; Jason H. Chen, BA; Felice Lin, BA; Jessica Lin, BA; Tiffany HaiVan Phan, BA; Heather A. Carleton, MPH; Linda K. McDougal, MS; Fred C. Tenover, PhD; Daniel E. Cohen, MD; Kenneth H. Mayer, MD; George F. Sensabaugh, DCrim; Françoise Perdreau-Remington, PhD
Acknowledgment: The authors thank Dr. David A. Talan for providing isolates and clinical data.
Grant Support: By U.S. Public Health Service grant R01/CCR923381 (Dr. Chambers); University of California, Berkeley, Faculty Research Grant (Dr. Sensabaugh); unrestricted grant from Pfizer (Dr. Perdreau-Remington); Microbial Pathogenesis and Host Defense Postdoctoral Fellowship (5T32AI060537-02) (Dr. Diep) and HIV Translational Research Fellowship (5T32AI060530-02) (Dr. Graber) from the University of California, San Francisco; and U.S. Public Health Service grant R01/CCR923419 (Dr. Miller).
Potential Financial Conflicts of Interest: None disclosed.
Reproducible Research Statement: Study protocol, statistical code, and portions of deidentified data are available from Dr. Diep (e-mail, firstname.lastname@example.org).
Requests for Single Reprints: Binh An Diep, PhD, Department of Medicine, University of California, San Francisco, San Francisco General Hospital, 1001 Potrero Avenue, Building 30, Room 3300, San Francisco, CA 94110; e-mail, email@example.com.
Current Author Addresses: Drs. Diep, Chambers, Graber, and Perdreau-Remington; Ms. Phan; and Ms. Carleton: University of California, San Francisco, San Francisco General Hospital, 1001 Potrero Avenue, Building 30, Room 3300, San Francisco, CA 94110.
Dr. Szumowski: Beth Israel Deaconess Medical Center, Deaconess 311, 330 Brookline Avenue, Boston, MA 02215.
Dr. Miller: Harbor-UCLA Medical Center, 1000 West Carson Street, Box 466, Torrance, CA 90509.
Dr. Han: State Laboratory Institute, 305 South Street, Jamaica Plain, MA 02130.
Mr. Chen, Ms. F. Lin, Ms. J. Lin, and Dr. Sensabaugh: School of Public Health, MC#7360, University of California, Berkeley, CA 94720.
Ms. McDougal and Dr. Tenover: Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333.
Dr. Cohen: Fenway Community Health, 7 Haviland Street, Boston, MA 02115.
Dr. Mayer: Brown University/Miriam Hospital, 164 Summit Avenue, Providence, RI 02906.
Author Contributions: Conception and design: B.A. Diep, C.J. Graber.
Analysis and interpretation of the data: B.A. Diep, C.J. Graber, J.D. Szumowski, L.G. Miller, L.L. Han, F.C. Tenover, D.E. Cohen, K.H. Mayer, G.F. Sensabaugh, F. Perdreau-Remington, H.F. Chambers.
Drafting of the article: B.A. Diep.
Critical revision of the article for important intellectual content: B.A. Diep, C.J. Graber, H.F. Chambers, G.F. Sensabaugh, F. Perdreau-Remington, J.D. Szumowski, L.G. Miller, L.L. Han, J.H. Chen, F. Lin, J. Lin, T.H. Phan, H.A. Carleton, L.K. McDougal, F.C. Tenover, D.E. Cohen, K.H. Mayer.
Final approval of the article: B.A. Diep, H.F. Chambers, C.J. Graber, J.D. Szumowski, L.G. Miller, L.L. Han, J.H. Chen, F. Lin, J. Lin, T.H. Phan, H.A. Carleton, L.K. McDougal, F.C. Tenover, D.E. Cohen, K.H. Mayer, G.F. Sensabaugh, F. Perdreau-Remington.
Provision of study materials or patients: H.F. Chambers, F. Perdreau-Remington, L.G. Miller, L.L. Han, D.E. Cohen, K.H. Mayer.
Statistical expertise: B.A. Diep, C.J. Graber, L.G. Miller.
Obtaining of funding: H.F. Chambers, G.F. Sensabaugh, F. Perdreau-Remington.
Collection and assembly of data: B.A. Diep, C.J. Graber, J.D. Szumowski, J.H. Chen, F. Lin, J. Lin, T.H. Phan, H.A. Carleton, L.K. McDougal, L.L. Han.
Infection with multidrug-resistant, community-associated, methicillin-resistant Staphylococcus aureus (MRSA) has been reported but seems to be isolated.
To determine the incidence of a multidrug-resistant MRSA clone (USA300) in San Francisco, and to determine risk factors for the infection.
Population-based survey and cross-sectional study using chart review.
9 hospitals in San Francisco (population-based survey) and 2 outpatient clinics in San Francisco and Boston (cross-sectional study).
Persons with culture-proven MRSA infections in 2004 to 2006.
Annual incidence, spatial clustering, and risk factors for multidrug-resistant USA300 infection. Pulsed-field gel electrophoresis, polymerase chain reaction assays, and DNA sequencing were used to characterize MRSA isolates.
The overall incidence of multidrug-resistant USA300 infection in San Francisco was 26 cases per 100 000 persons (95% CI, 16 to 36 cases per 100 000 persons); the incidence was higher in 8 contiguous ZIP codes with a higher proportion of male same-sex couples. Male–male sex was a risk factor for multidrug-resistant USA300 infection (relative risk, 13.2 [CI, 1.7 to 101.6]; P < 0.001) independent of past MRSA infection (relative risk, 2.1 [CI, 1.2 to 3.7]; P = 0.007) or clindamycin use (relative risk, 2.1 [1.2 to 3.6]; P = 0.007). The risk seemed to be independent of HIV infection. In San Francisco, multidrug-resistant USA300 manifested most often as infection of the buttocks, genitals, or perineum. In Boston, the infection was recovered exclusively from men who had sex with men.
The study was retrospective, and sexual risk behavior was not assessed.
Infection with multidrug-resistant USA300 MRSA is common among men who have sex with men, and multidrug-resistant MRSA infection might be sexually transmitted in this population. Further research is needed to determine whether existing efforts to control epidemics of other sexually transmitted infections can control spread of community-associated, multidrug-resistant MRSA.
Researchers have recently identified multidrug-resistant USA300, a clone of community-acquired, methicillin-resistant Staphylococcus aureus (MRSA) that is resistant to multiple antibiotics.
The authors demonstrate that the incidence of multidrug-resistant USA300 MRSA is highest in the areas of San Francisco where more male same-sex couples reside. The infection frequently manifests as an abscess or cellulitis in the buttocks, genitals, or perineum, and male–male sex was a risk factor.
Data were passively reported or retrospectively collected and are therefore subject to bias.
Multidrug-resistant USA300 MRSA infection is especially common among men who have sex with men. It might be sexually transmitted in this population.
Annual incidence of multidrug-resistant USA300 infection and percentage of male same-sex couples, by San Francisco ZIP code.
The key indicates the annual incidence of multidrug-resistant USA300 infection per 100 000 persons. The number within each ZIP code is the percentage of male same-sex couples, calculated by dividing the number of male same-sex, unmarried-partner households by the number of coupled (married and unmarried) households for each ZIP code, based on 2000 U.S. Census (Summary File 3) data (33). *Location of the San Francisco General Hospital HIV clinic.
Table 1. Distribution of Methicillin-Resistant Staphylococcus aureus Genotypes and Antimicrobial Resistance Profiles at the San Francisco General Hospital HIV Clinic
Table 2. Risk Factors for Multidrug-Resistant USA300 Infections among Outpatients in San Francisco and Boston*
Table 3. Adjusted Relative Risk for Multidrug-Resistant USA300 Infections among Outpatients Treated at the San Francisco General Hospital HIV Clinic*
Appendix Table. Primers Used in Sequencing of Multiresistance Conjugative Plasmid pUSA03
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Diep BA, Chambers HF, Graber CJ, Szumowski JD, Miller LG, Han LL, et al. Emergence of Multidrug-Resistant, Community-Associated, Methicillin-Resistant Staphylococcus aureus Clone USA300 in Men Who Have Sex with Men. Ann Intern Med. ;148:249–257. doi: 10.7326/0003-4819-148-4-200802190-00204
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Published: Ann Intern Med. 2008;148(4):249-257.
Infectious Disease, MRSA.
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