title: In vitro and in vivo evaluations of oxacillin efficiency against mecA-positive oxacillin-susceptible Staphylococcus aureus.
abstract: Community-type Staphylococcus aureus strains that are positive for mecA and PBP2a but appear phenotypically susceptible to oxacillin are increasingly reported worldwide. Four S. aureus clinical isolates carrying the mecA gene with oxacillin MICs of <2 microg/ml were tested for oxacillin efficiency by population analyses and experimental thigh infections. These isolates harbored staphylococcal cassette chromosome mec type IV and belonged to two genotypes. Two of the four isolates were found by population analysis to be truly oxacillin susceptible. All four isolates exhibited significant reductions in the numbers of colonies grown after dicloxacillin treatment of experimental thigh infections, as also did a mecA-negative S. aureus control strain. These observations indicate that some of the phenotypically oxacillin susceptible mecA-positive Staphylococcus aureus isolates may be at least partially responsive to oxacillin.
authors.affiliation: Department of Medical Microbiology, University Hospital of Larissa, Mezourlo, Larissa, Greece.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Ikonomidis
authors.forename: George
authors.initials: G
authors.lastname: Michail
authors.forename: Afroditi
authors.initials: A
authors.lastname: Vasdeki
authors.forename: Maria
authors.initials: M
authors.lastname: Labrou
authors.forename: Vasilis
authors.initials: V
authors.lastname: Karavasilis
authors.forename: Constantinos
authors.initials: C
authors.lastname: Stathopoulos
authors.forename: Antonios N
authors.initials: AN
authors.lastname: Maniatis
authors.forename: Spyros
authors.initials: S
authors.lastname: Pournaras
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D004009:Dicloxacillin / Q000494:pharmacology; D005798:Genes, Bacterial; D006801:Humans; D008297:Male; D016106:Methicillin Resistance / Q000235:genetics; D051379:Mice; D010068:Oxacillin / Q000494:pharmacology*; D010403:Penicillin Resistance / Q000235:genetics; D046915:Penicillin-Binding Proteins / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus; D014640:Vancomycin; D004009:Dicloxacillin; D010068:Oxacillin