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.

Testing the efficacy of Mueller Hinton agar over Nutrient agar for optimal antibiotic sensitivity testing response by selected clinical bacterial pathogens

“…The use of different codes and in some cases, different concentrations for the same antibiotics (as in brands being used in this study) reflects a state of much confusion which makes it difficult to make a direct and comprehensive comparison of the performance of these two brands. Ekundayo and Omodamiro [21] also reported similar challenges in their related study. These discrepancies may be a reflection of lack of clear policy guidelines on antibiotic usage or failure of manufacturers to comply with such guidelines.…”

“…The excess of two discs may have accounted for un-interpretable zones of inhibition (i.e large zones of inhibition that merged together or completely wiped out bacterial growth at the time of reading the plates) which were encountered in the course of reading the antibiograms. Some authors who did a related study also reported this experience [21].…”

Prevalence of Staphylococcus aureus among Clinical Isolates and their Responses to Selected Antibiotics at Centre Hospitalier Universitaire de Kigali (CHUK)

“…The following table summarizes results based on presence or absence of S. aureus and the age of the patient. Table 1 shows that the interval with both higher positive and negative results is [20][21][22][23][24][25][26][27][28][29] with 43.3 % and 32.5% respectively. The Table 1 also shows that 30 patients had S. aureus infection and 270 were free from it.…”

“…The procedure of the AST was done as described by Ekundayo et al [21]. After incubation, the plates were examined and the zone of inhibition was measured.…”

Comparative Study on Effectiveness of Commercial Antibiotic Discs in Federal Capital Territory (FCT), Nigeria

“…Clinically, antimicrobial susceptibility testing results provide guidance in the choice of antimicrobial agents in patient care [1]. The accuracy of results from antimicrobial susceptibility testing can be affected by multiple factors including the media, antimicrobial discs or preparations, inoculum's size, plate reading and incubation conditions [2].…”