Chapter 42 Antimicrobial Agents,A/P Zhi-Zhong Xie, Ph.D.,Section Chemotherapeutic drugs,ntimakrobil抗菌剂,kemu,erpju:tik化疗药物,Main contents,Common terms of antibacterial agents The mechanisms of action of antibacterial agents Bacterial resistance Application principle of antibacterial agents,ntimakrobil,Some Basic Concepts,Chemotherapy：It is defined as pharmacotherapy for diseases caused by a variety of pathogens, including pathogenic microorganisms (bacteria, fungi, viruses), parasite and cancer. Chemotherapeutic drugs: anti-pathogenic microorganism, anti-parasite, and anti-tumor drugs. Anti-pathogenic microorganism drugs include antibacterial agents, anti-viral agents and anti-fungal agents,pdnk,makrorgn,zm,抗病原微生物,About bacteria,Bacteria is different in morphology, structure, growth characteristics and dyeing property. So it can be classified upon these difference, like coccus, bacillus, spirilla, etc. Bacteria is usually classified into Gram positive bacteria and Gram negative bacteria base on the difference of the structure of cell wall.,sprl 螺旋菌,mrfldi形态学,kks 球菌,bsls 杆菌,Gram-positive bacteria Gram-positive cocci Gram-positive bacilli,Medically relevant gram-negative cocci include the three organisms that cause transmitted diseases (Neisseria gonorrhoeae), a meningitis (Neisseria meningitidis), and respiratory symptoms (Moraxella catarrhalis). Gram-negative bacilli include Salmonella, Escherichia, Pseudomonas, Bacteroides, Shigella, Proteus, Enterobacter, Citrobacter, Serratia, Yersinia species, etc.,Gram-positive coccus include Diplococci, like Streptococcus pneumoniae and Neisseria gonorrhoeae, Streptococci like Streptococcus pyogenes, Staphylococci like Staphylococcus aureus. Gram-positive bacilli include Clostridium, Corynebacterium, Listeria, Propionibacterium, etc.,Gram-negative bactaria Gram-negative cocci Gram-negative bacilli,bsilai,The classification of bacteria,:rs,Pharyngolaryngitis frlrndats,furuncle and carbuncle,stflkks,slmnl沙门氏菌属、 ,erikj 埃希氏杆菌属、 ,psju:dumns 假单胞菌属、 ,bktridi:z拟杆菌属、 iel志贺氏菌属、 prutju:s变形杆菌属、 ,entrubkt肠杆菌属、,Antibacterial spectrum,Narrow-spectrum antibiotics G+: -lactam antibiotics (Natural penicillins : Penicillin G, First generation cephalosporins), First generation Macrolides, Lincomycin & Clindamycin, vancomycin & teicoplanin G- (esp. G- bacilli) : Aminoglycosides ,minliksaid氨基糖苷类 Broad-spectrum antibiotics,Semi-synthetic penicillins (Ampicillin, Carbenicillin, etc.) , & Cephalosporins, sflsprn头孢菌素 Semisynthetic Macrolides (clarithromycin, roxythromycin, etc.) Tetracyclines ,ttrsakln四环素 Chloramphenicol Sulfonamides & Trimethoprim, Quinolones,slfnmadz 磺胺类& traimeprim甲氧苄啶,In the case of an infectious disease, which one should be used first?,kl:rmfenikl氯霉素,G+ & G-,mycoplasma, chlamydia, rickettsia, spirochete and actinomycete besides bacteria,喹诺酮kwinlun,kr,bnsln氨苄青霉素,Antibacterial activity,Antibacterial activity: Ability of a drug to inhibit or kill bacteria.,Bacteriostatic drugs: Drugs can inhibit the growth of bacteria. e.g. Macrolides, Lincomycin & Clindamycin, Tetracyclines, Chloramphenicol, Sulfonamides, Trimethoprim.,Bactericidal drugs (germicide): Drugs can kill bacteria. e.g. -lactam antibiotics, vancomycin & teicoplanin, Aminoglycosides, Quinolones,bk,tirisaidl,d:misaid灭菌剂,-内酰胺,vkmasn万古霉素tkplenn替考拉宁,minliksaid,喹诺酮kwinlun,kl:rmfenikl,Mechanism of action,Cell wall,Nucleic acid,Ribosome,Cytomembrane,Bacterial Structures,Bacteria are prokaryotes, whereas human cells are eukaryotes.,prokrt,jukriut,autolysin,autolytic enzymes,rabsom,saitumembrein,Mechanism of action,Agents that inhibit synthesis of bacterial cell walls,e.g. -lactams, vancomycin & teicoplanin Can kill bacteria (Bactericidal drugs) Only inhibit synthesis of bacterial cell walls but not destroyed the wall Only have effect on proliferating bacteria Have little effects on human cells Produce synergistic effect when used with aminoglycosides, however, produces antagonistic effect with macrolides.,Why?,sndstk协同作用,minliksaid,n,tnstk拮抗作用,mkrlaid,Mechanism of action,Agents that act directly on cell membrane,They disrupt bacterial cell membrane, affecting permeability and leading to leakage of intracellular compounds, and bacteria death. e.g. Aminoglycosides and the detergents such as polymyxins. Belong to bactericidal drugs and kill both the proliferating and quiescent bacteria Produce synergistic effect when used with -lactams, macrolides or Sulfonamides.,minliksaid,plimiksin多粘菌素,slfnmad,sndstk协同作用,Mechanism of action,Agents that inhibit protein synthesis,Agents that affect the function of 30S or 50S ribosomal subunits to cause a reversible inhibition of protein synthesis These bacterio