JAC Advance Access originally published online on February 19, 2008
Journal of Antimicrobial Chemotherapy 2008 61(4):966-967; doi:10.1093/jac/dkn061
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Letters to the Editor |
Comment on: Community-associated MRSA (CA-MRSA): an emerging pathogen in infective endocarditis
1 Section of Infectious Diseases, Department of Medicine, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan 2 National Yang-Ming University, Taipei, Taiwan 3 Institute of Environmental Education, National Kaohsiung Normal University, Kaohsiung, Taiwan
* Correspondence address. Section of Infectious Diseases and Department of Medicine, Kaohsiung Veterans General Hospital, 386 Ta-Chung 1st Road, Kaohsiung 813, Taiwan. Tel: +886-7-3468299; Fax: +886-7-3468292; E-mail: hctsai1011{at}yahoo.com.tw
Keywords: methicillin-resistant Staphylococcus aureus , definitions , S. aureus
Sir,
Although community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) have distinct microbiological, epidemiological and molecular characteristics different from those of healthcare-associated MRSA (HA-MRSA), currently, there are no validated definitions for CA-MRSA. We read with interest the newly proposed definitions published by Millar et al.1 In their article, comparing the differences between CA-MRSA and HA-MRSA, the authors also reviewed all published cases of CA-MRSA endocarditis to date.
There are several errors in the article by Millar et al.1 First, of the 23 patients with infective endocarditis due to CA-MRSA, 2 of the 7 cases in the Haque2 series (Cases 3 and 7) were in fact healthcare-associated, although all 7 cases were Panton–Valentine leucocidin (PVL)-positive and carried the SCCmecA type IV gene. In Taiwan, the most common SCCmec types in CA-MRSA infections were types IV and VT.3–5 MRSA colonized a substantial proportion of healthy children and accounted for 25% to 75% of the childhood CA-MRSA infections.3,4 However, SCCmec type IV can also be hospital-acquired and accounted for 40% to 43% of MRSA infections in two studies.4,6 This suggests that SCCmec type IV alone is not sufficient to indicate community acquisition and should not be the only criterion for CA-MRSA.
Secondly, in the table comparing clinical characteristics and outcome for patients with methicillin-susceptible S. aureus (MSSA) native valve endocarditis with those of MRSA and CA-MRSA native valve endocarditis (Table 3), it is unclear why only 81% of the CA-MRSA was community-acquired. What then is the definition of CA-MRSA if it does not satisfy the criteria of ‘community acquisition’?
We concur with the authors that emergence of CA-MRSA infection impacts significantly on the outcome and management of infective endocarditis. However, a comprehensive definition of CA-MRSA is still currently lacking, reflecting the complexity of this pathogen in its clinical, epidemiological and microbiological characteristics. We caution that a combination of characteristics, rather than a single one (such as SCCmec type IV genotype), should be used to define CA-MRSA.
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1 Millar BC, Prendergast BD, Moore JE. Community-associated MRSA (CA-MRSA): an emerging pathogen in infective endocarditis. J Antimicrob Chemother (2008) 61:1–7.
2 Haque NZ, Davis SL, Manierski CL, et al. Infective endocarditis caused by USA300 methicillin-resistant Staphylococcus aureus (MRSA). Int J Antimicrob Agents (2007) 30:72–7.[CrossRef][Web of Science][Medline]
3 Chen CJ, Huang YC. Community-acquired methicillin-resistant Staphylococcus aureus in Taiwan. J Microbiol Immunol Infect (2005) 38:376–82.[Medline]
4 Chen CJ, Huang YC, Chiu CH, et al. Clinical features and genotyping analysis of community-acquired methicillin-resistant Staphylococcus aureus infections in Taiwanese children. Pediatr Infect Dis J (2005) 24:40–5.[CrossRef][Web of Science][Medline]
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Boyle-Vavra S, Ereshefsky B, Wang CC, et al. Successful multiresistant community-associated methicillin-resistant Staphylococcus aureus lineage from Taipei, Taiwan, that carries either the novel staphylococcal chromosome cassette mec (SCCmec) type VT or SCCmec type IV. J Clin Microbiol (2005) 43:4719–30.
6 Huang YH, Tseng SP, Hu JM, et al. Clonal spread of SCCmec type IV methicillin-resistant Staphylococcus aureus between community and hospital. Clin Microbiol Infect (2007) 13:717–24.[CrossRef][Medline]
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  B. C. Millar, B. D. Prendergast, and J. E. Moore Community-associated MRSA (CA-MRSA): an emerging pathogen in infective endocarditis--authors' response J. Antimicrob. Chemother., April 1, 2008; 61(4): 967 - 968. [Full Text] [PDF]
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