African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5211

Full Length Research Paper

Comparison of mecA gene-based PCR with CLSI cefoxitin and oxacillin disc diffusion methods for detecting methicillin resistance in Staphylococcus aureus clinical isolates

Soodabeh Rostami1, Mojtaba Moosavian2*, Saeed Shoja1, Maryam Torabipour1 and Zahra Farshadzadeh3
1Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Iran. 2Deparment of Microbiology, School of Medicine, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences. Iran. 3Department of Microbiology, Tehran University of Medical Sciences. Iran.
Email: [email protected]

  •  Accepted: 26 April 2013
  •  Published: 21 May 2013


The emergence of heterogeneous populations of methicillin-resistant Staphylococcus aureus (MRSA) causes major problems in routine screening for MRSA. Cefoxitin is a potent inducer of the mecA regulatory system and can be use for detection of heterogeneous populations of MRSA. Detection of the mecA gene by PCR was considered to be the “gold standard”. In this study we determined the sensitivity and specificity of the oxacillin disk diffusion test, cefoxitin disk diffusion test and oxacillin agar screening for detection of MRSA. A total of 124 non-duplicate isolates of S. aureus were included in the study. Methicillin resistance was measured using oxacillin (1μg) and cefoxitin(30μg) disc diffusion method and oxacillin agar screening test (6 mg/ml oxacillin) according to CLSI guideline and PCR for the mecA gene. Compared with the molecular detection of methicillin resistance the overall sensitivities and specificities of the phenotypic tests for cefoxitin disc diffusion were 100%, for oxacillin disc diffusion were 91.7 and 92.8% and for oxacillin agar screening were 95 and 95.5%, respectively. We concluded that in the absence of availability of molecular biology techniques, the cefoxitin disc was the best detector of methicillin resistance in S. aureus related to the other phenotypic tests.


Key words: Methicillin-resistant Staphylococcus aureus, mecA, Cefoxitin, polymerized chain reaction