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Community-Acquired Methicillin-Resistant Staphylococcus aureus: An Emerging Pathogen

  • Battolili Saïd-Salim (a1), Barun Mathema (a1) and Barry N. Kreiswirth (a1)


The prevalence of MRSA in the nosocomial setting has been well studied, and its control remains a challenge for infection control professionals. Complicating this problem is the increasing number of reports on the spread of community-acquired MRSA (CA-MRSA). CA-MRSA strains differ from hospital-acquired MRSA (HA-MRSA) strains in that they are generally susceptible to most antibiotics. These strains share the presence of staphylococcal cassette chromosome mec (SCCwec) type IV in their genomes, are frequently virulent, and predominantly cause skin and soft tissue infections. The genome sequence of the prototypic CA-MRSA strain, MW2, revealed the presence of additional virulence factors not commonly present in other S. aureus strains.

We determined the genetic relatedness of 30 geographically diverse CA-MRSA isolates clustered based on SCCmec type IV by sequence analysis of the polymorphic repeat region of the protein A gene (spa typing). These results indicated that most strains shared a common spa type (131), identical to MW2. Because this group tends to infect healthy individuals with no known risk factors for nosocomial acquisition of MRSA, we refer to it as CA-MRSA without risk factors. A second group, CA-MRSA with risk factors, consists of two related genotypes, spa types 1 and 7, which differ by one nucleotide change. These strains have caused severe infections in HIV-positive patients in Los Angeles and New York.

Although CA-MRSA strains share genetic determinants, they are not clonal but rather are derived from different genetic backgrounds. The genetic characteristics and the epidemiology of CA-MRSA with and without risk factors are discussed.


Corresponding author

Public Health Research Institute, 225 Warren Street, Newark, NJ 07103-3535


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1.National Nosocomial Infections Surveillance System. National Nosocomial Infections Surveillance (NNIS) System report: data summary from January 1990-May 1999, issued June 1999. Am J Infect Control 1999;27:520532.
2.Lowy, FD. Staphylococcus aureus infections. N Engl J Med 1998;339:520532.
3.Outbreaks of community-associated methicillin-resistant Staphylococcus aureus skin infections: Los Angeles County, California, 2002-2003. MMWR 2003;52:88.
4.Fey, PD, Said-Salim, B, Rupp, ME, et al.Comparative molecular analysis of community- or hospital-acquired methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2003;47:196203.
5.Herold, BC, Immergluck, LC, Maranan, MC, et al.Community-acquired methicillin-resistant Staphylococcus aureus in children with no identified predisposing risk. JAMA 1998;279:593598.
6.Chang, S, Sievert, DM, Hageman, JC, et al.Infection with vancomycin-resistant Staphylococcus aureus containing the vanA resistance gene. N Engl J Med 2003;348:13421347.
7.Pillai, SK, Sakoulas, G, Wennersten, C, et al.Linezolid resistance in Staphylococcus aureus: characterization and stability of resistant phenc-type. J Infect Dis 2002;186:16031607.
8.Hiramatsu, K, Katayama, Y, Yuzawa, H, Ito, T. Molecular genetics of methicillin-resistant Staphylococcus aureus. Int J Med Microbiol 2002;292:6774.
9.Ito, T, Katayama, Y, Asada, K, et al.Structural comparison of three types of staphylococcal cassette chromosome mec integrated in the chromosome in methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2001;45:13231336.
10.Rubin, RJ, Harrington, CA, Poon, A, Dietrich, K, Greene, JA, Moiduddin, AThe economic impact of Staphylococcus aureus infection in New York City hospitals. Emerg Infect Dis 1999;5:917.
11.Chambers, HEThe changing epidemiology of Staphylococcus aureus? Emerg Infect Dis 2001;7:178182.
12.Shopsin, B, Mathema, B, Martinez, J, et al.Prevalence of methicillin-resistant and methicillin-susceptible Staphylococcus aureus in the community. J Infect Dis 2000;182:359362.
13.Charlebois, ED, Bangsberg, DR, Moss, NJ, et al.Population-based community prevalence of methicillin-resistant Staphylococcus aureus in the urban poor of San Francisco. Clin Infect Dis 2002;34:425433.
14.Groom, AV, Wolsey, DH, Naimi, TS, et al.Community-acquired methicillin-resistant Staphylococcus aureus in a rural American Indian community. JAMA 2001;286:12011205.
15.Gross-Schulman, S, Dassey, D, Mascola, L, Anaya, C. Community-acquired methicillin-resistant Staphylococcus aureus. JAMA 1998;280:421422.
16.Daum, RS, Ito, T, Hiramatsu, K, et al.A novel methicillin-resistance cassette in community-acquired methicillin-resistant Staphylococcus aureus isolates of diverse genetic backgrounds. J Infect Dis 2002;186:13441347.
17.L'Heriteau, F, Lucet, JC, Scanvic, ABouvet, E. Community-acquired methicillin-resistant Staphylococcus aureus and familial transmission. JAMA 1999;282:10381039.
18.Jones, TF, Kellum, ME, Porter, SS, Bell, M, Schaffner, W. An outbreak of community-acquired foodborne illness caused by methicillin-resistant Staphylococcus aureus. Emerg Infect Dis 2002;8:8284.
19.Salmenlinna, S, Lyytikainen, O, Vuopio-Varkila, J. Community-acquired methicillin-resistant Staphylococcus aureus, Finland. Emerg Infect Dis 2002;8:602607.
20.Salgado, CD, Farr, BM, Calfee, DP. Community-acquired methicillin-resistant Staphylococcus aureus: a meta-analysis of prevalence and risk factors. Clin Infect Dis 2003;36:131139.
21.Berman, DS, Eisner, W, Kreiswirth, B. Community-acquired methicillin-resistant Staphylococcus aureus infection. N Engl J Med 1993;329:1896.
22.Centers for Disease Control and Prevention. Four pediatric deaths from community-acquired methicillin-resistant Staphylococcus aureus: Minnesota and North Dakota, 1997-1999. JAMA 1999;282:11231125.
23.Baba, T, Takeuchi, F, Kuroda, M, et al.Genome and virulence determinants of high virulence community-acquired MRSA. Lancet 2002;359:18191827.
24.Oliveira, DC, Tomasz, A, de Lencastre, H. Secrets of success of a human pathogen: molecular evolution of pandemic clones of methicillin-resistant Staphylococcus aureus. Lancet Infect Dis 2002;2:180189.
25.Roberts, RB, de Lencastre, A, Eisner, W, et al.Molecular epidemiology of methicillin-resistant Staphylococcus aureus in 12 New York hospitals: MRSA Collaborative Study Group. J Infect Dis 1998;178:164171.
26.Dinges, MM, Orwin, PM, Schlievert, PM. Exotoxins of Staphylococcus aureus. Clin Microbiol Rev 2000;13:1634.
27.Naimi, TS, LeDell, KH, Boxrud, DJ, et al.Epidemiology and clonality of community-acquired methicillin-resistant Staphylococcus aureus in Minnesota, 1996-1998. Clin Infect Dis 2001;33:990996.


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