title: [Phenotypic methods for detection of methicillin-resistant Staphylococcus aureus].
abstract: BACKGROUND
  Cefoxitin is a potent inducer of the mecA gene. It is currently as a screening recommended method for presumptive identification of isolates of methicillin resistant Staphylococcus aureus (MRSA). The aim of the study was to compare the sensitivity and specificity of the cefoxitin disc diffusion (30 μg) to oxacillin agar screening from detection of the mecA gene by PCR.
  
  
  METHODS
  Three hundred thirty-one strains of S. aureus isolated from blood cultures of patients from hospitals in Lima were used in the study. The following tests were performed: oxacillin screening agar (plates were inoculated with 4% NaCl and 6 mg/L of oxacillin), cefoxitin disc diffusion test (30 ug) and PCR to amplify the mecA gene.
  
  
  RESULTS
  The mecA gene was detected in 165 out of 331 S. aureus isolates. Thus, the frequency of detection of MRSA was 50%. The evaluation of the cefoxitin disc diffusion test showed a 96.3% and 90.9% of sensitivity and specificity, respectively.
  
  
  CONCLUSIONS
  Cefoxitin disc diffusion test correlated well with detection of the mecA gene by PCR. Therefore, this test can be an alternative to PCR for detection of MRSA in limited resources settings.
authors.affiliation: Gertrudis Horna, Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano He-redia, Lima Perú. Av.Honorio Delgado # 430 - Urb Ingenieria - SMP - Lima- Perú. sara.horna@upch.pe.
authors.forename: G
authors.initials: G
authors.lastname: Horna
authors.forename: L
authors.initials: L
authors.lastname: Astocondor
authors.forename: J
authors.initials: J
authors.lastname: Jacobs
authors.forename: C
authors.initials: C
authors.lastname: García
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002440:Cefoxitin / Q000494:pharmacology*; D005189:False Positive Reactions; D006801:Humans; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; C046756:5'-N-methylcarboxamideadenosine; D002440:Cefoxitin; D000241:Adenosine; D010068:Oxacillin