Ghulam Mujtaba Siddiqui, Abdul Hannan.
Comparison of standard Kirby-Bauer and modified Kirby-Bauer disk diffusion methods for the detection of methicillin resistance among staphylococcus.
Pak J Pathol Nov ;7(2):37-41.

Methicillin-resistance (MR) amongst Staphylococcus has posed a serious problem of hospital and community-acquired infections. The problem becomes greater in view of the fact that there are several methods proposed for the detection of this resistance. To resolve this problem, 623 clinical isolates (Staphylococcus aureus n=499, Staphylococcus epidermidis n=112, Staphylococcus saprophyticus n=12) were tested by the standard KirbyBauer method (using 5 ug methicillin disk, plain Mueller-Hinton agar, 35°C, 16-18 h incubation). The minimum inhibitory concentration (MIC) of methicillin was performed as the standard method for comparing the results of these two disk diffusion methods.The standard Kirby-Bauer method was found to pick up only 71 (11.3%) strains as MR. However, the modified Kirby-Bauer methods picked up 132 (21.1%) methicillin-resistant strains which was exactly the number picked up with the MIC determination. To avoid missing any MR Staphylococcus and hence preventing treatment failure, it is recommended to adopt the modified Kirby-Bauer instead of the standard Kirby-Bauer method for the determination of resistance pattern of organisms.

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