title: Subtyping of Chilean Methicillin-Resistant Staphylococcus aureus strains carrying the staphylococcal cassette chromosome mec type I.
abstract: The cassette chromosome mec (SCCmec) present in methicillin-resistant Staphylococcus aureus (MRSA) has two essential components, the ccr gene complex and the mec gene complex. Additionally, SCCmec has non-essential components called J regions which are used for MRSA subtyping. This study was performed to determine subtypes MRSA strains carrying SCCmec type I based on polymorphism of regions located downstream of the mecA gene. A total of 98 MRSA strains carrying SCCmec type I isolated from patients hospitalized at the County Hospital of Valdivia (Chile) between May 2007 and May 2008, were analyzed by multiplex PCR designed to amplify the mecA gene and 7 DNA hypervariable regions located around the mecA gene. MRSA strains were classified into seventeen genotypes accordingly to amplification patterns of DNA hypervariable regions. Five genotypes showed amplification patterns previously described. The remaining twelve genotypes showed new amplification patterns. Genotypes 18 and Genotype 19 were the most frequently detected. Regions HVR, Ins117 and pI258 stand out as being present in more than 60% of tested isolates. The acquisition of hypervariable regions by MRSA is a continuous horizontal transfer process through which the SCCmec have been preserved intact, or even may give rise to new types and subtypes of SCCmec. Therefore it is possible to infer that most MRSA strains isolated at the County Hospital of Valdivia (Chile) were originated from two local clones which correspond to Genotype 18 and Genotype 19.
authors.affiliation: Instituto de Microbiología Clínica, Facultad de Medicina, Universidad Austral de Chile , Valdivia , Chile.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Medina
authors.forename: Carola
authors.initials: C
authors.lastname: Otth
authors.forename: Laura
authors.initials: L
authors.lastname: Otth
authors.forename: Heriberto
authors.initials: H
authors.lastname: Fernández
authors.forename: Celeste
authors.initials: C
authors.lastname: Muñoz
authors.forename: Maria
authors.initials: M
authors.lastname: Cruz
authors.forename: Angela
authors.initials: A
authors.lastname: Zaror
authors.forename: Ruby
authors.initials: R
authors.lastname: Henriquez
authors.forename: Maria
authors.initials: M
authors.lastname: Arce
authors.forename: Myra
authors.initials: M
authors.lastname: Wilson
keywords: SCCmec MRSA; Subtypified MRSA; polymorphism MRSA
references.citation: Drug Resist Updat. 2003 Feb;6(1):41-52
references.pmid: 12654286
references.citation: J Med Microbiol. 1998 Apr;47(4):341-51
references.pmid: 9569001
references.citation: Antimicrob Agents Chemother. 2000 Jul;44(7):1906-10
references.pmid: 10858352
references.citation: Antimicrob Agents Chemother. 1999 Jun;43(6):1449-58
references.pmid: 10348769
references.citation: J Clin Microbiol. 2001 Feb;39(2):779-81
references.pmid: 11158151
references.citation: J Antimicrob Chemother. 2007 Jul;60(1):42-8
references.pmid: 17468509
references.citation: J Clin Microbiol. 2005 Oct;43(10):5026-33
references.pmid: 16207957
references.citation: J Clin Microbiol. 1997 Oct;35(10):2580-7
references.pmid: 9316911
references.citation: J Bacteriol. 1991 Dec;173(23):7416-22
references.pmid: 1718947
references.citation: Antimicrob Agents Chemother. 2004 Jul;48(7):2637-51
references.pmid: 15215121
references.citation: J Clin Microbiol. 2002 Aug;40(8):3093-7
references.pmid: 12149390
references.citation: Trends Microbiol. 2001 Oct;9(10):486-93
references.pmid: 11597450
references.citation: Antimicrob Agents Chemother. 2001 May;45(5):1323-36
references.pmid: 11302791
references.citation: Rev Med Chil. 2007 May;135(5):596-601
references.pmid: 17657328
references.citation: Antimicrob Agents Chemother. 2002 Jul;46(7):2155-61
references.pmid: 12069968