Evaluation Of The Quality Of Locally Manufactured Antimicrobial Susceptibility Testing Discs Used In South Eastern Nigeria

Abstract

Locally manufactured antimicrobial susceptibility discs are becoming increasingly used in both private and government hospital laboratories in Nigeria. Data on the quality of these locally manufactured antimicrobial discs are not available. In order to provide some data, we evaluated the quality of three brands of locally manufactured antimicrobial susceptibility discs in common use in southeastern Nigeria. The three brands are Brodisk, Jirehdisk and Optudisc. The performances of these brands in agar disc diffusion assay against clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli were compared with that of 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 Optudisc and Jiredisk brands. The imported brand, Abtek, did not produce any such results. While Gentamycin on Abtek produced a mean diameter of zone of inhibition of 15mm, 19mm and 16mm against S. aureus, P. aeruginosa and E. coli respectively, the same antibiotic disc with the same stated potency on Brodisk an Jiredisk produced no zone of inhibition against the test bacteria. Amoxylin and Augmentin discs on Abtek produced zones of inhibition of 13mm
and 21mm against S. aureus respectively. Amoxylin disc on Brodisk did not produce any zone of inhibition against the bacterial strain while Augmentin disc on Jirehdisk produced un-interpretable result. Of the three locally made brands, Brodisk is the only one that conformed to the international standard of not having more than eight discs per
90mm plate. In our opinion, Brodisk 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.

African Journal of Clinical and Experimental Microbiology Vol. 9 (3) 2008: pp. 122-128