上克通大睾 Concept 1:antibiotic spectrum Shanghai Jiao Tong University Different antibiotics target different kinds of bacteria Antimicrobial spectrum Antimicrobial spectrum of a drug means the species of microorganisms that the drug can inhibit or kill. ©Narrow spectrum The agents act against a single or limited group of microorganisms (isoniazid:mycobacteria Extended spectrum The agent that are effective against gram-positive organisms and also against a number of gram- negative bacteria (ampicillin). ©Broad spectrum The agent affect a wide variety of microbial species (tetracycline)
Shanghai Jiao Tong University Concept 1: antibiotic spectrum Different antibiotics target different kinds of bacteria Antimicrobial spectrum Antimicrobial spectrum of a drug means the species of microorganisms that the drug can inhibit or kill. Narrow spectrum The agents act against a single or limited group of microorganisms (isoniazid: mycobacteria ) Extended spectrum The agent that are effective against gram-positive organisms and also against a number of gram- negative bacteria (ampicillin). Broad spectrum The agent affect a wide variety of microbial species (tetracycline)
Concept 2: 上游充通大学 Bacteriostatic vs.Bactericide Shanghai Jiao Tong University Antibiotics differ by mode of action ©Bacteriostatic: arrest the growth or replication of the microorganism. Sulfanilamide ©Bactericide: The agents which can kill the microorganisms are called bactericidal drugs;a drug may be bacteriostatic for one organism but bactericidal for another. Fluoroquinolones,Penicillins
Shanghai Jiao Tong University Concept 2: Bacteriostatic vs. Bactericide Antibiotics differ by mode of action Bacteriostatic: arrest the growth or replication of the microorganism. Sulfanilamide Bactericide: The agents which can kill the microorganisms are called bactericidal drugs; a drug may be bacteriostatic for one organism but bactericidal for another. Fluoroquinolones, Penicillins, …
上游充通大￥ Concept 3: Shanghai Jiao Tong University Bactericidal-MBC,bacteriostatic-MIC Chemotherapy index(Cl) To evaluate the safety of chemotherapeutic drugs, the value is LD5o/ED50 Minimal inhibitory concentration (MIC) MIC is the lowest concentration of antimicrobial agents that prevents visible growth in 18-24 hours incubation
Shanghai Jiao Tong University Concept 3: Bactericidal-MBC, bacteriostatic-MIC Chemotherapy index (CI) To evaluate the safety of chemotherapeutic drugs, the value is LD50 /ED50 Minimal inhibitory concentration (MIC) MIC is the lowest concentration of antimicrobial agents that prevents visible growth in 18-24 hours incubation
h 上游充通大睾 inoculum of test bacteria growth medium+ antibiotic antibiotic 16 4 2 0.5 0.25 0.12mg/1 concentration overnight incubation read MIC MIC of antibiotic =1 mg/l subculture to drug-free 16 8 2 0.5· 0.25 0.12mg/ agar overnight incubation MIC of read MBC antibiotic 2 mg/l Fig.30.35 More precise measures of the amount of antibiotic the standard method as outlined in this illustration,the MIC result is required to inhibit and kill a bacterial population can be estimated available after 24 hours and the MBC result after 48 hours.A by establishing the minimum inihibitory concentration(MIC)and number of variables such as the inoculum size,the growth medium minimum bactericidal concentration(MBC)of the antibiotic.Using and the interpretation of the results affect the results of MIC tests
Shanghai Jiao Tong University
上游充通大￥ Concept 4: 后 Shanghai Jiao Tong University Post antlbiotic effect The antibiotic inhibits microbial multiplication beyond the time when the MIC is reached in plasma. ·Aminoglycosides ·Macrolides Allows reduction in dosing schedule
Shanghai Jiao Tong University Concept 4: Post antibiotic effect The antibiotic inhibits microbial multiplication beyond the time when the MIC is reached in plasma. • Aminoglycosides • Macrolides Allows reduction in dosing schedule