RT Journal Article SR Electronic T1 Comparison of antibiotic discs from different sources. JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 779 OP 783 DO 10.1136/jcp.28.10.779 VO 28 IS 10 A1 Brown, D F A1 Kothari, D YR 1975 UL http://jcp.bmj.com/content/28/10/779.abstract AB Antibiotic discs from Oxoid, Mast, AB Biodisk, Difco, and Baltimore Biological Laboratories were compared, where discs of similar antibiotic content were available, in diffusion-sensitivity tests against organisms of known sensitivity. Discs from Oxoid and Mast gave zones 1-5 mm larger than discs from other manufacturers with penicillin 2 units, ampicillin 10 mug, cephalothin 30 mug, methicillin 10 mug, carbenicillin 100 mug, erythromycin 15 mug, chloramphenicol 50 mug, and trimethoprim 1-25 mug, while discs containing aminoglycoside antibiotics, lincomycin, fusidic acid, tetracycline, nalidixic acid, penicillin 10 units, and polymyxin B gave similar zone sizes whatever the source. Where tested, different batches of single discs from the same source did not vary significantly in antibiotic content as indicated by variation in zone size; but with some antibiotics Multodisks gave larger zones than single discs from the same source. The implications of these differences are discussed.