title: Evaluation of the BIOCEN GC agar medium base in antimicrobial susceptibility testing of Neisseria gonorrhoeae.
abstract: BACKGROUND
  Since 1995, the Cuban Reference Laboratory for Neisseria has been monitoring the antibiotic susceptibility of gonococci, following the methodology of the National Committee for Clinical Laboratory Standards, which uses GC agar medium base supplemented with 1% Vitox. We evaluated three lots of GC agar medium base produced by BIOCEN, Cuba, in antibiotic susceptibility testing of reference and wild strains of gonococci.
  
  
  METHODS
  The susceptibilities to five antibiotics were evaluated five times on three lots of GC agar medium base from BIOCEN. Four and one gonococcal reference strains were tested by MIC dilution and disc diffusion methods, respectively. Later, the antimicrobial susceptibilities of ten wild Neisseria gonorrhoeae strains were tested in triplicate. As internal control, a GC agar medium from Difco was used.
  
  
  RESULTS
  All antibiotic MICs obtained on four lots of GC agar medium from different manufacturers fell within the proposed quality control limits for reference strains analyzed. The disc diffusion data for the reference strain of N. gonorrhoeae ATCC 49226 to five antibiotics provided essentially identical results in all lots of GC agar medium base. For wild strains of gonococci, identical modal MIC values and zone size diameters within a 3-mm range were observed in all the antibiotics tested.
  
  
  CONCLUSIONS
  Excellent agreement in susceptibility testing methods among different lots of GC agar medium base from BIOCEN and Difco was obtained for all reference and wild gonococcal strains and antibiotics tested. We proposed that GC medium from BIOCEN can be used in antimicrobial susceptibility testing of N. gonorrhoeae by MIC dilution and disc diffusion tests.
authors.affiliation: Department of Bacteriology, Tropical Medicine Institute Pedro Kourí (IPK), La Habana, Cuba. llanes@ipk.sld.cu
authors.forename: Rafael
authors.initials: R
authors.lastname: Llanes
authors.forename: Calixto
authors.initials: C
authors.lastname: Domínguez
authors.forename: Alberto
authors.initials: A
authors.lastname: Prat
authors.forename: Claudio
authors.initials: C
authors.lastname: Rodríguez
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Valdés
authors.forename: Oderay
authors.initials: O
authors.lastname: Gutiérrez
authors.forename: Daymi
authors.initials: D
authors.lastname: Guzmán
mesh_terms: D000362:Agar / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001431:Bacteriological Techniques; D003462:Cuba; D004352:Drug Resistance, Microbial; D008826:Microbial Sensitivity Tests; D009344:Neisseria gonorrhoeae / Q000378:metabolism*; D015203:Reproducibility of Results; D013045:Species Specificity
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D000362:Agar