The purpose of this test is to determine the sensitivity or resistance of a pathogenic aerobic or facultative anaerobic bacterium to various antimicrobial compounds in order to assist a physician for selecting treatment options for his or her patients. When a 6mm filter paper disk impregnated with a known concentration. Similar to the kirbybauer assay, a confluent lawn of a bacterial isolate is inoculated onto the surface of an agar plate. Can disc diffusion susceptibility tests assess the. The kirbybauer disc method this method is also called the agar diffusion method or the disk diffusion method.
Inoculation of bacterial lawn is made from broth culture diluted to. The disk diffusion method of kirby and bauer has been standardized and is a viable alternative to broth dilution methods for laboratories. Modified kirbybauer disc diffusion method for antimicrobial. Antimicrobial susceptibility testing by disc diffusion method. Placing antibiotic disc in muellerhinton agar medium. Laboratory protocols level 2 training course susceptibility.
To determine the susceptibility of a microbial species against different antibiotic agents. The disc diffusion or kirbybauer method involves spreading bacteria on an agar plate and placing paper discs impregnated with antibiotic on the plate. Before throwing out that old antibiotic in freezer, give it quick test this versatile assayit may save you some money. Neither the supplements nor the procedural modification are. White filter paper disks 6 mm in diameter are impregnated with known amounts of antimicrobial agents. Kirbybauer disk diffusion susceptibility test protocol asm. Jul 28, 2010 however, no agarbased susceptibility testing method has been standardized for the testing of dermatophytes. Students perform a modification of the kirbybauer disk diffusion assay, allowing them to use a standardized protocol that relies on basic laboratory skills, collect quantitative data including enumeration, then use the ttest and anova to test hypotheses. Kirby bauer testing measures sensitivity of bacteria to antibiotics by culturing bacteria on solid growth media surrounding sources of drug. Uses of antibiotic sensitivity testing antibiotic sensitivity test. Agar well diffusion method is widely used to evaluate the antimicrobial activity of plants or microbial extracts.
Kirbybauer disc diffusion assay lenzmeier research laboratory page 2 analysis of antibiotics. Testing an antibiotic using a disk diffusion assay kirby bauer method. The kirbybauer test, known as the diskdiffusion method, is the most widely used antibiotic susceptibility test in determining what choice of antibiotics should be used when treating an infection. Method for antifungal disk diffusion susceptibility. The agar used is meullerhinton agar that is rigorously tested for composition and ph. First, a pure culture of bacteria is isolated from the patient. The kirbybauer test for antibiotic susceptibility, called the disc diffusion test, is a standard that has been used for years. Even though the majority of labs are following the correct protocol, some of you still dont have the current guidelines. Method for antifungal disk diffusion susceptibility testing of yeasts. Antibiotic susceptibility test was performed using kirby bauer disc diffusion method following the guidelines laid down by the clinical laboratory standard instituteclsi 26. Jun 02, 2011 kirbybauer disc diffusion method antibiotic susceptibility testing skill based learning dr.
Bauer, then standardized by the world health organization in 1961. Kirbybauer antibiotic sensitivity biology libretexts. Agar plug diffusion method is often used to highlight the antagonism between microorganisms, and the procedure is similar to that used in the diskdiffusion method. Disc diffusion or the kirbybauer test is one of the classic microbiology techniques, and it is still very commonly used. October4th,2016 igemstockholm2016 kirbybauer disk diffusion test aim. The procedure followed is simply that a filter disk impregnated with an antibiotic is applied to the surface of an agar plate containing the organism to be tested. Kirby bauer test standards muellerhinton agar ph of 7. Interpreting the results of the bauer kirby method of antibiotic susceptibility testing duration. Agarbased disk diffusion assay for susceptibility testing of. The etest is an alternative method used to determine mic, and is a combination of the kirby bauer disk diffusion test and dilution methods. First developed in the 1950s, it was refined and by w. Antibiotic susceptibility test was performed using kirbybauer disc diffusion method following the guidelines laid down by the clinical laboratory standard instituteclsi 26. It is not suitable for bacteria that are slowgrowing, need special nutrients, or require co2 or anaerobic incubation. A laboratory test which determines how effective antibiotic therapy is against a bacterial infections.
In 1940, heatley introduced the use of adsorbent paper for carrying antimicrobial solutions. The disc diffusion method for antibiotic susceptibility testing is the kirby bauer method. The kirbybauer test, known as the diskdiffusion method, is the most widely. Disk diffusion susceptibility testing kirby bauer method i have been asked many times to interpret the susceptibility results from labs outside addl. Because of convenience, efficiency, and cost, the disc diffusion method is probably the most widely used method for determining antimicrobial resistance around the world. October4th,2016 igemstockholm2016 kirby bauer disk diffusion test aim. The use of disc diffusion susceptibility tests to determine the antibacterial activity of engineered nanoparticles enps is questionable because their low diffusivity practically prevents them from penetrating through the culture media.
In this study, we investigate the ability of such a test, namely the kirbybauer disc diffusion test, to determine the antimicrobial activity of au and ag. Kirbybauer disk diffusion susceptibility test protocol asmscience. Kirbybauer testing measures sensitivity of bacteria to antibiotics by culturing bacteria on solid growth media surrounding sources of drug. This method relies on the inhibition of bacterial growth measured under standard conditions. Kirbybauer disk diffusion susceptibility test protocol protocol pdf the kirbybauer disk diffusion susceptibility test determines the sensitivity or resistance of pathogenic bacteria to various antimicrobial compounds in order to assist physicians in selecting treatment options their patients. It has been superseded in clinical labs by automated tests. Kirbybauer antibiotic testing also called kb testing or disk diffusion antibiotic sensitivity testing uses antibioticcontaining wafers or disks to test whether particular bacteria are susceptible to specific antibiotics. Dec 08, 2009 protocol pdf the kirby bauer disk diffusion susceptibility test determines the sensitivity or resistance of pathogenic bacteria to various antimicrobial compounds in order to assist physicians in selecting treatment options their patients. The purpose of the kirbybauer disk diffusion susceptibility test is to. In this test, small filter paper disks 6 mm impregnated with a standard amount of antibiotic are placed onto an agar plate to which bacteria have been swabbed. The procedure, which is accepted by the national committee for clinical laboratory standards nccls, is a modification of that described by bauer, kirby, sherris, and turck. Correspondingly, izd variations of the agar disk diffusion method lay within an izd variation of 3 to 4 mm. Students perform a modification of the kirby bauer disk diffusion assay, allowing them to use a standardized protocol that relies on basic laboratory skills, collect quantitative data including enumeration, then use the ttest and anova to test hypotheses.
The etest is an alternative method used to determine mic, and is a combination of the kirbybauer disk diffusion test and dilution methods. The procedure followed is simply that a filter disk impregnated with an antibiotic is applied to the surface of an agar plate containing the organism to be tested and the plate is incubated at 37c for 2448 hours. Kirbybauer disk diffusion susceptibility test protocol. Methods for in vitro evaluating antimicrobial activity. Clinical and laboratory standards institute, 950 west valley road, suite 2500, wayne, pennsylvania 19087 usa, 2009. Kirbybauer test antimicrobialimpregnated paper disks are placed on plate inoculated to form a bacterial lawn. The disk diffusion method is performed using muellerhinton agar mha, which. Measure from the center of the antimicrobial disk to a point on the circumference of the zone where a distinct edge is. In this disc technique both the test and control organisms are inoculated on the same plate. To check the efficacy of antibiotics against bacteria, we recommend using a disc diffusion assay, also known as kirby bauer assay. The purpose of the kirbybauer disk diffusion susceptibility test is to determine the sensitivity or resistance of pathogenic aerobic and facultative anaerobic bacteria to various antimicrobial compounds in order to assist a physician in selecting. Testing the effectiveness of antimicrobials microbiology. Bsac disc diffusion method for antimicrobial susceptibility testing version 2.
The purpose of the kirby bauer disk diffusion susceptibility test is to determine the sensitivity or resistance of pathogenic aerobic and facultative anaerobic bacteria to various antimicrobial compounds in order to assist a physician in selecting. Testing an antibiotic using a disk diffusion assay kirby bauer. The disk diffusion method of kirby and bauer has been standardized and is a viable alternative to broth dilution methods for laboratories without the resources to utilize the newer automated methods for broth microdilution testing. The disk diffusion test, or agar diffusion test, or kirbybauer test discdiffusion antibiotic susceptibility test, discdiffusion antibiotic sensitivity test, kb test, is a test of the antibiotic sensitivity of bacteria. A comparison of disc diffusion and microbroth dilution.
Measuring drug susceptibility boundless microbiology. Muellerhinton agar mha is the best medium to use for routine antimicrobial susceptibility testing using kirbybauer disc diffusion method for nonfastidious bacteria both aerobe and facultative anaerobe. The kirby bauer agar diffusion method is well documented and is the standardized method for determining antimicrobial susceptibility. It involves making an agar culture of the strain of interest on its appropriate culture medium by tight streaks on the plate surface. Advantages of a standardized disk diffusion based assay for evaluating the antifungal susceptibility of dermatophytes include the ease of use, reproducibility, accuracy, and low cost 1, 3, 10, 15, 16, 22. Disk diffusion testing gonorrhea std information from cdc. Comparison of broth microdilution, etest, and agar disk. Antimicrobial susceptibility testing ast types and.
Muellerhinton agar mha is the best medium to use for routine antimicrobial susceptibility testing using kirby bauer disc diffusion method for nonfastidious bacteria both aerobe and facultative anaerobe. Reliability of the kirbybauer disc diffusion method for. The resulting concentration gradient establishes the organisms supposed susceptibility to supposed agent. Students perform a disk diffusion assay according to the protocol recommended. Using a forceps, place each specific antibiotic paper disk presoakedyou dont need to do anything on the gramnegative plate as shown on the next page. Kirby bauer method and the liquid media based microbroth dilution method. The kirby bauer test for antibiotic susceptibility also called the disc diffusion test is a standard that has been used for years. There are a number of different methods of ast such as agar dilution, broth dilution and disc diffusion assays. Recommended for antimicrobial disc diffusion susceptibility testing of common, rapidly growing bacteria by the bauerkirby method, as standardized by the clinical and laboratory standards instituteclsi. All aspects of the kirby bauer procedure are standardized to ensure consistent and accurate results. The number of plates required per strain tested will depend on the anticipated zone inhibition diameters of the antimicrobial agents to be tested. The kirby bauer test, known as the disk diffusion method, is the most widely used antibiotic susceptibility test in determining what choice of antibiotics should be used when treating an infection.
What differences between kirbybauer test and disk diffusion. Introduction the mic minimal inhibitory concentration of a bacterium to a certain antimicrobial agent gives a quantitative estimate of the susceptibility. Kirby bauer test and disk diffusion test are the same thing. The disk diffusion method of kirby and bauer has been standardized and is a viable. Disk diffusion susceptibility testing kirbybauer method. Use of media other than muellerhinton agar may result in erroneous results. The disc diffusion method for antibiotic susceptibility testing is the kirbybauer method.
Similarly to the procedure used in disk diffusion method, the agar plate surface is inoculated by spreading a volume of the microbial inoculum over the entire agar surface. Even though the majority of labs are following the correct protocol, some of you still dont have the. Protocol for using the kirbybauer disk diffusion susceptibility test in the microbiology lab. The kirby bauer test for antibiotic susceptibility, called the disc diffusion test, is a standard that has been used for years. It uses antibiotic discs to test the extent to which bacteria are affected by those antibiotics. Antimicrobial susceptibility testing microbiology resource.
Further the depth of the agar in the plate is a factor to be considered in the disc diffusion method. Similar to the kirby bauer assay, a confluent lawn of a bacterial isolate is inoculated onto the surface of an agar plate. Bsac disc diffusion method for antimicrobial susceptibility. Kirby bauer disk diffusion susceptibility test protocol, an alternate method for measuring zones. Bauerkirby disk diffusion this is one of the more commonly used methods of antimicrobial susceptibility testing. The kirbybauer test for antibiotic susceptibility also called the disc diffusion test is a standard that has been used for years. Complies with requirements of the world health organization and is specified in the fda. If the zones of adjacent antimicrobial disks overlap, the zone diameter can be determined by measuring the radius of the zone. Kirbybauer disk diffusion susceptibility test protocol, an alternate method for measuring zones. Diffusion method of antimicrobial susceptibility test was developed in 1940s. The disk diffusion test, or agar diffusion test, or kirbybauer test is a test of the antibiotic sensitivity of bacteria. Kirby bauer antibiotic sensitivity student health center. Using a disk diffusion assay to introduce statistical methods.