title: Comparison of different phenotypic and genotypic methods for the detection of methicillin-resistant Staphylococcus aureus.
abstract: BACKGROUND
  Staphylococcus aureus is known as a powerful pathogen that causes various infections. Emergence of methicillin-resistant S. aureus (MSRA) is responsible for nosocomial and community-acquired infections worldwide.
  
  
  OBJECTIVE
  The present study aimed to evaluate the performance and ability of eight different phenotypic and genotypic methods for the detection of MSRA.
  
  
  METHODS
  A total of 186 S. aureus isolates were defined as methicillin-susceptible S. aureus (MSSA; 95) and MSRA (91) using polymerase chain reaction (PCR) as the gold standard. Susceptibility to methicillin was investigated using oxacillin, methicillin, cefotetan, cefoxitin, and cefmetazole disks, by oxacillin Adata Tab and strips. For all S. aureus isolates minimal inhibitory concentrations of oxacillin were determined using the broth microdilution method according to Clinical and Laboratory Standards Institute guidelines.
  
  
  RESULTS
  Among the diagnostic methods studied, broth microdilution and the cefoxitin disk had the highest specificity (98.9 and 94.7%), sensitivity (100 and 98.9%), and concordance with PCR results (98.9 and 93.6%). The cefotetan and cefmetazole disks had the lowest concordance with PCR results.
  
  
  CONCLUSIONS
  Our results suggest that microdilution and cefoxitin disk methods have high sensitivities compared with other methods for detection of MSRA. The cefoxitin disk method may be preferred in clinical laboratories because it is easy to perform and does not require special equipment.
authors.affiliation: Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Farahani
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Parviz
authors.initials: P
authors.lastname: Mohajeri
authors.affiliation: Department of Pharmacology and Toxicology, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Babak
authors.initials: B
authors.lastname: Gholamine
authors.affiliation: Department of Biological Statistics, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Mansour
authors.initials: M
authors.lastname: Rezaei
authors.affiliation: Department of Pharmacology and Toxicology, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Abbasi
keywords: Cefoxitin; Detection method; Genotypic; Methicillin; Methicillin-resistant S. aureus; Phenotypic; Staphylococcus aureus