The in vitro testing of bacterial cultureswith antibiotics
The in vitro testing of bacterial cultureswith antibiotics todetermine. K Hari Krishnan Tirunelveli Medical College
Antibiotic Sensitivity Testing K Hari Krishnan Tirunelveli Medical College
To guide the clinician in selecting the best antibioticagent for anindividual patient. To control the useof in clinical practice. To accumulate epidemiological information on the resistance of microorganisms of public health importance within the community. To reveal the changingtrendsin the local isolates. K Hari Krishnan Tirunelveli Medical College
Bacteria havethe ability to develop resistance following repeated or subclinical (insufficient) doses, so more advanced antibiotics and synthetic antibiotics are continually required to overcome them. K Hari Krishnan Tirunelveli Medical College
ASTis essential for the selection of the K Hari Krishnan Tirunelveli Medical College
– For the testing of isolates from “healthy” patients with intact immune defenses. – For such as uncomplicated urinary tract infections. – In the treatment of seriousinfectionssuch as endocarditis or osteomyelitis. – For infections in high-risk patient groups such as immunocompromisedpatients (e. g. . transplant patients). – Those who are critically ill. K Hari Krishnan Tirunelveli Medical College
Antibiotic. Sensitivity. Tests Diffusion Kirby-Bauer Method Diffusion& Dilution Stokes Method Qualitative. Methods Tube Dilution Agar Dilution E-Test Quantitative. Methods K Hari Krishnan Tirunelveli Medical College
Enterobacteriaceae Staphylococcus Intestinal Urinary Blood & Tissues Pseudomonas aeruginosa Ampicillin Sulfonamides Ampicillin Piperacillin Oxacillin Chloramphenicol Trimethoprim Chloramphenicol Gentamycin Erythromycin Cotrimoxazole Tobramycin Tetracycline Ampicillin Tetracycline Cefalotin Nitrofurantoin Gentamycin Drug s Benzylpenicillin Chloramphenicol Tetracycline K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
– A paper disk with adefined amount of antibiotic is used to generate adynamicallychanginggradient ofantibiotic concentrationsin the agarin the vicinity of the disk. K Hari Krishnan Tirunelveli Medical College
The contained in areservoir is allowed to and interact in aplate freshly seeded with the test organisms. The disk is applied to the surface of an agarplate inoculated with the test organism. – The diffuses out of the disk to form gradient. starts to divide and grow and – The progresses toward acritical massof cells. K Hari Krishnan Tirunelveli Medical College
is formed at the critical time where a particular concentration of the antibiotic is just able to inhibit the organism before it reaches an overwhelming cell mass or critical mass. K Hari Krishnan Tirunelveli Medical College
Any commercially available discs with the proper diameter and potency canbe used. Stocks of antibiotic discs canbe stored at -20⁰C for 1 month. – On removal from the refrigerator, the containers should be left at room temperature for about 1 hour to allow the temperature to equilibrate. K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
Used to determinethe of antibiotic to inhibit or kill the microorganism. Achieved bydilution of antibiotic in either agaror brothmedia. K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
The lowest concentration of drugthat of the bacteria isolated from the patient. The MIC is determined byinoculating the organism isolated from the patient into a series of tubes or cups containing progressive dilutions of the drug. K Hari Krishnan Tirunelveli Medical College
Patient's organism is added to tubes containing decreasing amounts of the antibiotic Incubation At 37°Covernight Lowest concentration of drug that inhibits growth is the MIC K Hari Krishnan Tirunelveli Medical College
MIC K Hari Krishnan Tirunelveli Medical College
The lowest concentration of drugthat the bacteria isolated from the patient. K Hari Krishnan Tirunelveli Medical College
Serial dilutions of the drug are preparedniagarand poured into plates. – Many strains canbe inoculated on each plate containing an antibiotic dilution. K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
Broth microdilution platecontains – Eachrow: • standard dilutions of eight by letters A-H). in each row (denoted – Each column • contains a standard right to left. concentration that doubles whenmoving from The minimum inhibitory concentration (MIC) is determined bythe first well where there is no visible growth. K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
Epsilometer Test Quantitative method of antibiotic se ytesting. tvnitsi Applies both dilution of antibiotic and diffusion of antibiotic into the medium. K Hari Krishnan Tirunelveli Medical College
Combines the principles of disk diffusion and agar dilution methods Diffusion E-Test Dilution K Hari Krishnan Tirunelveli Medical College
A predefined stable antibioticgradientspresent i on athin inert carrier strip. Using innovative dry chemistry technology, E-Test is used to determine the on-scale Minimum Inhibitory Concentration (MIC). K Hari Krishnan Tirunelveli Medical College
The intersection of the inhibitory zone edgeand the calibrated carrier strip indicates the MIC with inherent K Hari Krishnan Tirunelveli Medical precision and accuracy. College
MIC K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
– Pneumococci – Haemophilus – Helicobacter pylori – Meningococci – Gonococci – Fungi – Mycobacteria K Hari Krishnan Tirunelveli Medical College
K Hari Krishnan Tirunelveli Medical College
Antibiotic Sensitivity Testing K Hari Krishnan Tirunelveli Medical College
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