ABSTRACT

The study evaluated the quality of two brands of locally manufactured antimicrobial susceptibility discs in common use in southeastern Nigeria with the imported brand. The two brands are Optun disc, and Maxicare together with the Abtek brand which is the foreign one. The performances of these brands in agar disc diffusion assay against clinical isolates of staphylococcus aureus, pseudomonas aeruginosa and Escherichia coli were compared with the Abtek, the imported brand. Un-interpretable Zones of inhibition defined as large zones of inhibition that merged together or complete wiping out of bacterial growth at the time of reading of the plate, were common with the Optun disc brand. The imported brand, Abtek, did not produce any such result. While Gentamicin on Abtek produced a mean diameter of zone of inhibition of 19mm, 18mm, and 9mm against S. aureus, P. aeruginosa and E.coli respectively, the same antibiotic disc with the same stated antibiotic concentration on Optun disc produced 25mm, 20mm and 24mm with higher zone of inhibition against the test organisms or bacteria, Maxi disc is the only one that conformed to the International Standard of not having more than eight discs per 90mm plate. In our opinion, Maxicare disc can be recommended for clinical use in Nigeria with further improvement. The outcome of this study indicates the need for improved standardization in the production of these locally manufactured susceptibility discs.