title: Reproducibility of control organism zone diameters for batches of IsoSensitest agar manufactured from 1996 to 2000 using the BSAC disc susceptibility test method.
abstract: The BSAC Working Party on Susceptibility Testing has recently suggested that the performance of IsoSensitest agar has changed since 1991. Twenty batches of IsoSensitest agar that had been manufactured between 1996 and 2000 were tested using the BSAC standardized disc susceptibility testing method. Antibiotic discs containing amoxicillin 10 microg, ceftazidime 30 microg, gentamicin 10 microg, ciprofloxacin 1 microg and colistin sulphate 25 microg were tested on each batch of media 12 times against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 where appropriate. There was a small reduction in zone sizes for most antibiotics on batches of media that were near their expiration date, but otherwise zone sizes were remarkably consistent. We could find no evidence to suggest that a change in the performance of IsoSensitest agar for the disc diffusion method had occurred since 1996.
authors.affiliation: Department of Microbiology, Royal Gwent Hospital, Gwent Healthcare NHS Trust, Newport NP20 2UB, UK.
authors.forename: Janine
authors.initials: J
authors.lastname: Landrygan
authors.forename: Peter A
authors.initials: PA
authors.lastname: James
authors.forename: Dawn
authors.initials: D
authors.lastname: Brooks
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Kubiak
mesh_terms: D000362:Agar / Q000032:analysis*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003470:Culture Media / Q000032:analysis; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D008826:Microbial Sensitivity Tests / Q000379:methods* / Q000706:statistics & numerical data* / Q000639:trends; D011550:Pseudomonas aeruginosa / Q000254:growth & development; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D000362:Agar