Key words antifungal, antimicrobial, disk, disk diffusion, kirby bauer method, susceptibility testing sample. Autoplay when autoplay is enabled, a suggested video will. Modified kirbybauer disc diffusion test method is a reference method which could be used as a routine technique to test the sensitivity of the isolate in the clinical laboratory. The disk diffusion method of kirby and bauer has been standardized and is a viable alternative to broth dilution methods for laboratories without. Kirbybauer disk diffusion susceptibility test protocol, an alternate method for measuring zones. The agar disc diffusion assay was determined in triplicate according to the. Singledisk diffusion testing kirbybauer of susceptibility. 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.
Thirtytwo percent of 756 clinical isolates of proteus mirabilis were of intermediate susceptibility to chloramphenicol, a higher percentage than for any other species. It uses antibiotic discs to test the extent to which. Laboratory protocols level 2 training course susceptibility. Lecture 9 antimicrobial susceptibility testing disk diffusion. The kirby bauer test for antibiotic susceptibility, called the disc diffusion test, is a standard that has been used for years. Kirby bauer method and the liquid media based microbroth dilution method. Seasonality impels the antibiotic resistance in kelani. Reliability of the kirbybauer disc diffusion method for. The kirbybauer method is currently widely used by clinical laboratories and best incor porates many of the features recommended by the world health organization. Method for antifungal disk diffusion susceptibility. Protocol for using the kirbybauer disk diffusion susceptibility test in the microbiology lab. We have tested the closeness of this relationship by comparing 20,000 simultaneous. A comparison of disc diffusion and microbroth dilution.
The inoculum for the disk diffusion method is prepared using a suitable broth. The kirbybauer disc method this method is also called the agar diffusion method or the disk diffusion method. The kirbybauer test for antibiotic susceptibility, called the disc diffusion test, is a standard that has been used for years. The agar used is meullerhinton agar that is rigorously tested for composition and ph. This medium is prepared according to manufacturers instructions, dispensed in tubes at 45 ml and sterilized. Reliability of the kirby bauer disc diffusion method for detecting methicillinresistant strains of staphylococcus aureus w. The disk diffusion test, or agar diffusion test, or kirbybauer test is a test of the antibiotic sensitivity of bacteria. Of particular importance is the concept of efficacy ratios. This method relies on the inhibition of bacterial growth measured under standard conditions. This is a method to determine the sensitivity of microorganisms to specific antimicrobial drugs.
Disc diffusion or the kirbybauer test is one of the classic microbiology techniques, and it is still very commonly used. 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. Measure from the center of the antimicrobial disk to a point on the circumference of the zone where a distinct edge is. First developed in the 1950s, it was refined and by w. Kirby bauer disk diffusion susceptibility test protocol, an alternate method for measuring zones. Because cloxacillin, nafcillin, and oxacillin are structurally and pharmacologically related to methicillin, detection ofresistance. Further the depth of the agar in the plate is a factor to be considered in the disc diffusion method. Kirbybauer disk diffusion susceptibility test protocol. Pdf on apr 1, 20, vikas gautam and others published reliability of kirbybauer disk diffusion method for detecting carbapenem resistance in acinetobacter baumanniicalcoaceticus complex. Modified kirbybauer disc diffusion method for antimicrobial. The uses and limitations of disc diffusion in the antibiotic. Stokes disc diffusion technique is not as highly standardized as the kirby bauer technique and is used in laboratories particularly when the exact amount of antimicrobial in a disc cannot be guaranteed due to difficulties in obtaining discs and storing them correctly or when the other conditions required for the kirby bauer technique cannot be met. Even though the majority of labs are following the correct protocol, some of you still dont have the current guidelines.
Disc diffusion in agar is a common method of testing the sensitivity of bacteria to antibiotics. 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. Bauer, then standardized by the world health organization in 1961. It uses antibiotic discs to test the extent to which bacteria are affected by those antibiotics. It has been superseded in clinical labs by automated tests. Disk diffusion susceptibility testing kirbybauer method. Jan 17, 2016 interpreting the results of the bauer kirby method of antibiotic susceptibility testing.
The disk diffusion method of kirby and bauer has been standardized and is a viable alternative to broth dilution methods for laboratories. 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. The disc diffusion method was originally described in 1966, and is well standardized and has been widely evaluated. Dec 08, 2009 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. Antimicrobial susceptibility assay was done using kirby bauer disk diffusion technique. Resistance for norfloxacin, ciprofloxacin, levofloxacin, kanamycin monosulfate km, tetracycline tc, and sulfamethoxazole st was measured with kirby bauer disc diffusion method. In order to eliminate or minimize variability in this testing, bauer et al. The kirbybauer test, known as the diskdiffusion method, is the most widely used antibiotic susceptibility test in. Modified kirby bauer disc diffusion test method is a reference method which could be used as a routine technique to test the sensitivity of the isolate in the clinical laboratory. Agar diffusion tests are often used as qualitative methods to determine whether a bacterium is resistant, intermediately resistant or susceptible.
In addition to a typical certificate of analysis coa, we also test our antibiotics through a modified version of the kirby bauer method, also known as the disk diffusion method. Mar 10, 2012 kirbybauer test is a agar disk diffusion method kirby bauer agar disk diffusion method provides qualitative interpretive category results of susceptible, interme diate, and resistant bacterial isolates. Testing an antibiotic using a disk diffusion assay kirby. Bsac disc diffusion method for antimicrobial susceptibility testing version 2. Kirby bauer testing measures sensitivity of bacteria to antibiotics by culturing bacteria on solid growth media surrounding sources of drug. In addition, the use of nonsupplemented muellerhinton agar in lieu of supplemented muellerhinton agar should make antifungal susceptibility testing more readily. The microbroth dilution method has become more widely used due to its ability to become automated, however, the kirby bauer method may be able to detect subpopulations of resistant bacteria that would be visualized as inner colonies in the zone of diffusion. The disc diffusion method for antibiotic susceptibility testing is the kirby bauer method. Media are supplemented with 12% sodium chloride nacl if intended for.
Kirbybauer disk susceptibility test biology libretexts. The significance of the intermediate category of the singledisk diffusion test kirby bauer of antibiotic susceptibility has never been clearly defined. Pdf reliability of kirbybauer disk diffusion method for. Josephs hospital, tampa, fl 33607 abstract antimicrobial susceptibility testing by the disc diffusion method is discussed with emphasis on the need for standardization of methodology.
The breakpoint separating susceptible and intermediate isolates nearly. Mankind has made very good use of these antimicrobials in its fight against infectious disease. Kirbybauer disk diffusion susceptibility test protocol asmscience. Kirbybauer test for antibiotic susceptibility a true antibiotic is an antimicrobial chemical produced by microorganisms against other microorganisms. Disk diffusion susceptibility testing kirby bauer method i have been asked many times to interpret the susceptibility results from labs outside addl. Antimicrobial susceptibility testing by the kirbybauer disc diffusion. Pdf the significance of the intermediate category of the singledisk. Bsac disc diffusion method for antimicrobial susceptibility. 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. A microorganism is judged sensitive or resistant according to the diameter of the zone of inhibition of cultural growth, which is then correlated statistically with the minimal inhibitory concentration mic. Antimicrobial susceptibility testing by the kirbybauer disc.
Enumerate the methods used for antimicrobial susceptibility testing ast 6. Bauer kirby disk diffusion this is one of the more commonly used methods of antimicrobial susceptibility testing. Pdf singledisk diffusion testing kirbybauer of susceptibility of. Kirbybauer antibiotic sensitivity biology libretexts. 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. The kirbybauer test for antibiotic susceptibility also called the disc diffusion test is a standard that has been used for years.
Aug 15, 20 in addition to a typical certificate of analysis coa, we also test our antibiotics through a modified version of the kirby bauer method, also known as the disk diffusion method. Antimicrobial susceptibility testing by the disc diffusion method is discussed with emphasis on the need for standardization of methodology. Jun 01, 20 kirbybauer disc diffusion assay lenzmeier research laboratory page 1 kirbybauer disk diffusion susceptibility test for antibiotics, disinfectants and antiseptics the disk diffusion technique is used to determine the antibacterial activity of antibiotics and disinfectants. If the zones of adjacent antimicrobial disks overlap, the zone diameter can be determined by measuring the radius of the zone. Have detailed theoretical knowledge on how to perform the main methods in a laboratory 8. The kirby bauer method is currently widely used by clinical laboratories and best incor. The disk diffusion method is performed using muellerhinton agar mha, which.
Bauerkirby disk diffusion this is one of the more commonly used methods of antimicrobial susceptibility testing. Interpreting the results of the bauer kirby method of antibiotic susceptibility testing. In this document, we attempt to answer many of the frequently asked questions regarding antimicrobial susceptibility testing. Kirby bauer antibiotic sensitivity student health center. Kirbybauer disk diffusion susceptibility test protocol asm. Because of convenience, efficiency, and cost, the disc diffusion method is probably the most widely used method for determining antimicrobial resistance around the world. 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.
However, the agar diffusion method can be used for determination of mic values provided the necessary reference curves for conversion of inhibition zones into mic values are available. It is relatively simple from a technicological standpoint and accurate and reproducible so. Pdf the significance of the intermediate category of the singledisk diffusion test kirbybauer of antibiotic susceptibility has never been. Antibiotic susceptibility test disc diffusion method duration. The resistance of staphylococcus aureus to methicillin and related drugs can be reliably determined by using the kirbybauer method of susceptibility testing if the incubation temperature is 35 c or below, but resistance may be missed at 37 c. Sherris department of pathology and laboratory medicine, mount zion hospital and medical center, san francisco, california 94120.
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