1/26/2016 Antihelminthic drugs Tests to Guide Chemotherapy -Prevent ATP production -Alter membrane permeability Learning Objective -Interfere with nutrient absorption -Paralyze the helminths Describe two tests for microbial susceptibility to chemotherapeutic agents. Susceptibility to Antimicrobials The Diffusion Methods Disk-diffusion method(Kirby-Bauer test) Different in different species and -Tests the effectiveness of chemotherapeutic strains agents Changes with time,even during therapy Several tests are used to indicate an The chemotherapeutic agent diffuses into the agar effective therapeutic agent The further the agent diffuses the lower the concentration -Broth dilution tests If the agent is effective,a zone of no growth around the disk occurs -Disk-Diffusion Method -E-test to the agent1/26/2016 9 • Antihelminthic drugs – Prevent ATP production – Alter membrane permeability – Interfere with nutrient absorption – Paralyze the helminths Tests to Guide Chemotherapy Learning Objective Describe two tests for microbial susceptibility to chemotherapeutic agents. Susceptibility to Antimicrobials • Different in different species and stra ns i • Changes with time, even during therapy • Several tests are used to indicate an effective therapeutic agent – B th dil ti t sts Broth dilution tests – Disk-Diffusion Method – E-test The Diffusion Methods • Disk-diffusion method (Kirby-Bauer test) – Tests the effectiveness of chemotherapeutic agents • Paper disks with a chemotherapeutic agent are placed on agar containing the test organism • The chemotherapeutic agent diffuses into the agar • The further the agent diffuses the lower the concentration • If the agent is effective, a zone of no growth around the disk occurs • Zone of inhibition around the disk determines the sensitivity of the organism to the antibiotic • The zone diameter is measured and the larger the zone of inhibition the more sensitive the microbe is to the agent