title: The arginine catabolic mobile element and staphylococcal chromosomal cassette mec linkage: convergence of virulence and resistance in the USA300 clone of methicillin-resistant Staphylococcus aureus.
abstract: The epidemic character of community-associated methicillin-resistant Staphylococcus aureus, especially the geographically widespread clone USA300, is poorly understood. USA300 isolates carry a type IV staphylococcal chromosomal cassette mec (SCCmec) element conferring beta-lactam antibiotic class resistance and a putative pathogenicity island, arginine catabolic mobile element (ACME). Physical linkage between SCCmec and ACME suggests that selection for antibiotic resistance and for pathogenicity may be interconnected. We constructed isogenic mutants containing deletions of SCCmec and ACME in a USA300 clinical isolate to determine the role played by these elements in a rabbit model of bacteremia. We found that deletion of type IV SCCmec did not affect competitive fitness, whereas deletion of ACME significantly attenuated the pathogenicity or fitness of USA300. These data are consistent with a model in which ACME enhances growth and survival of USA300, allowing for genetic "hitchhiking" of SCCmec. SCCmec in turn protects against exposure to beta-lactams.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, San Francisco General Hospital, University of California, San Francisco 94110, USA.
authors.forename: Binh An
authors.initials: BA
authors.lastname: Diep
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Stone
authors.forename: Li
authors.initials: L
authors.lastname: Basuino
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Graber
authors.forename: Alita
authors.initials: A
authors.lastname: Miller
authors.forename: Shelley-Ann
authors.initials: SA
authors.lastname: des Etages
authors.forename: Alison
authors.initials: A
authors.lastname: Jones
authors.forename: Amy M
authors.initials: AM
authors.lastname: Palazzolo-Ballance
authors.forename: Françoise
authors.initials: F
authors.lastname: Perdreau-Remington
authors.forename: George F
authors.initials: GF
authors.lastname: Sensabaugh
authors.forename: Frank R
authors.initials: FR
authors.lastname: DeLeo
authors.forename: Henry F
authors.initials: HF
authors.lastname: Chambers
mesh_terms: D000818:Animals; D016470:Bacteremia / Q000382:microbiology; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D044404:Genomic Islands; D020071:Interspersed Repetitive Sequences; D008297:Male; D016106:Methicillin Resistance; D010802:Phylogeny; D011817:Rabbits; D017384:Sequence Deletion; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D004269:DNA, Bacterial