The Bauer Kirby procedure is a standardized method for the determination of antimicrobial susceptibility based on the agar gel disc diffusion principle.^1-3 This method is published as a consensus standard by the National Committee for Clinical Laboratory Standards (NCCLS) and is periodically reviewed and updated.⁴

The inoculum concentration has been shown to be an important factor in obtaining valid results with the Bauer Kirby procedure.^2-5 The original Bauer- Kirby procedure employed inoculum prepared from log phase cultures. This requires incubation in broth for several hours to achieve the desired inoculum density, equivalent to the 0.5 McFarland turbidity standard, which produces approximately 1 x 10⁸ CFU/mL.^3-5 Several studies have subsequently shown that direct standardization of the inoculum, i.e., without incubation, is an acceptable alternative.^5-7 The direct adjustment of inoculum preparation is the preferred method for fastidious organisms that may grow slowly in broth. The M2-T4 edition of the NCCLS disc diffusion standard contained a revised procedure for Haemophilus influenzae, in which a new medium, Haemophilus Test Medium (HTM), was employed.⁸ This procedure recommended matching the inoculum density to the 0.5 McFarland standard using a photometric device.

The BBL Prompt Inoculation System is a device that allows direct standardization of inoculum without adjustment of turbidity or preincubation.^9-11 This method is considered acceptable for routine testing purposes.⁴ It has been shown that the Prompt system is also satisfactory for preparing inoculum for H. influenzae in the Bauer-Kirby procedure.

Agar diffusion methods employing dried filter paper discs impregnated with specific concentrations of antimicrobial agents were developed in the 1940s. In order to eliminate or minimize variability in this testing, Bauer et al. developed a standardized procedure in which Mueller Hinton Agar was selected as the test medium.^1,2

Various regulatory agencies and standards-writing organizations subsequently published standardized reference procedures based on the Bauer-Kirby method. Among the earliest and most widely accepted of these standardized procedures were those published by the U.S. Food and Drug Administration (FDA)³ and the World Health Organization (WHO).^4,5 The procedure was adopted as a consensus standard by the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) and is periodically updated.^6,7 The latest CLSI documents should be consulted for current recommendations.

Blank Discs, 1/4" diam. S&S-470

Taxo A discs are impregnated with a low level of bacitracin. According to the work of Maxted, of Levinson and Frank, and others, the group A streptococci may be differentiated from the other Lancefield groups of hemolytic streptococci by the formation of a zone of inhibition around the disc.

Taxo A discs are impregnated with a low level of bacitracin. According to the work of Maxted, of Levinson and Frank, and others, the group A streptococci may be differentiated from the other Lancefield groups of hemolytic streptococci by the formation of a zone of inhibition around the disc.

Gordon and McLeod described the oxidase test for detecting colonies of Neisseria.¹ Kovacs described the oxidase test for Pseudomonas.²

Neisseria, Pseudomonas and certain other microorganisms possess an oxidizing enzyme which acts in the presence of air on certain aromatic amines to produce colored compounds.^3,4 Color changes are produced by the indicator in contact with a colony of the organism.

Because the reagent used for the test is very unstable in liquid form, the original test procedures required that the reagent be made fresh, the dye being active only a few hours. The reagent remains quite stable, however, when impregnated into paper discs, dried, and stored in the refrigerator or freezer.

Taxo P Discs are impregnated with ethylhydrocupreine hydrochloride (optochin), a drug used for pneumonia therapy before sulfonamides became available. The growth of pneumococci, but not of other streptococci, is markedly inhibited by this chemical.^1,2 Pneumococci may, therefore, be differentiated from other alpha-hemolytic streptococci by the formation of a zone of inhibition around a Taxo P disc placed on a blood agar plate heavily inoculated with a pure culture suspected to be Streptococcus pneumoniae.

Taxo P Discs are impregnated with ethylhydrocupreine hydrochloride (optochin), a drug used for pneumonia therapy before sulfonamides became available. The growth of pneumococci, but not of other streptococci, is markedly inhibited by this chemical.^1,2 Pneumococci may, therefore, be differentiated from other alpha-hemolytic streptococci by the formation of a zone of inhibition around a Taxo P disc placed on a blood agar plate heavily inoculated with a pure culture suspected to be Streptococcus pneumoniae.

Taxo P Discs are impregnated with ethylhydrocupreine hydrochloride (optochin), a drug used for pneumonia therapy before sulfonamides became available. The growth of pneumococci, but not of other streptococci, is markedly inhibited by this chemical.^1,2 Pneumococci may, therefore, be differentiated from other alpha-hemolytic streptococci by the formation of a zone of inhibition around a Taxo P disc placed on a blood agar plate heavily inoculated with a pure culture suspected to be Streptococcus pneumoniae.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

The ability of an organism to ferment a specific carbohydrate incorporated in a basal medium, resulting in production of acid and gas, has been used to characterize bacteria and aid in differentiation.

In 1949, Soto developed miniaturized fermentation tests using carbohydrate-impregnated paper discs.¹ Sanders et al. subsequently developed a screening method for identification of Enterobacteriaceae using reagent-impregnated discs.²

Taxo Carbohydrate Discs are paper discs impregnated with a variety of fermentable carbohydrates. When added to inoculated basal media, the patterns of fermentation reactions aid in identification of test organisms.

Blank Discs, 1/2" diam.

Taxo™ ONPG Discs are used for the detection of lactose fermenters, especially those that do not promptly ferment lactose in some routine identification media such as Triple Sugar Iron Agar (TSI Agar) or Kligler Iron Agar.

These discs are used for semi-quantitative in vitro susceptibility testing by the agar disc diffusion test procedure of common, rapidly growing and certain fastidious bacterial pathogens. These include the Enterobacteriaceae, Staphylococcus spp., Pseudomonas spp., Acinetobacter spp., Enterococcus spp., Vibrio cholerae and, by modified procedures, Haemophilus influenzae, Neisseria gonorrhoeae, Streptococcus pneumoniae and other streptococci. NOTE: Special procedures are required for testing pneumococci, enterococci and methicillin/oxacillin-resistant staphylococci, for performing ß-lactamase tests and for screening and confirmatory tests for ESBLs; see the “RESULTS” section.

These discs are used for semi-quantitative in vitro susceptibility testing by the agar disc diffusion test procedure of common, rapidly growing and certain fastidious bacterial pathogens. These include the Enterobacteriaceae, Staphylococcus spp., Pseudomonas spp., Acinetobacter spp., Enterococcus spp., Vibrio cholerae and, by modified procedures, Haemophilus influenzae, Neisseria gonorrhoeae, Streptococcus pneumoniae and other streptococci. NOTE: Special procedures are required for testing pneumococci, enterococci and methicillin/oxacillin-resistant staphylococci, for performing ß-lactamase tests and for screening and confirmatory tests for ESBLs; see the “RESULTS” section.