Antimicrobial Chemotherapy Antibiotics

Transcription

1 약과건강 - 항생물질 Antimicrobial Chemotherapy Antibiotics Sun-Young Chang, Ph.D. 1 Lab of Microbiology College of Pharmacy Ajou University

2 Chemotherapeutic Agents chemical agents used to treat disease destroy pathogenic microbes or inhibit their growth within host most are antibiotics microbial products or their derivatives that kill susceptible microbes or inhibit their growth 2

3 Penicillin first discovered by Ernest Duchesne (1896), but discovery lost accidentally discovered by Alexander Fleming (1928) observed penicillin activity on contaminated plate did not think could be developed further effectiveness demonstrated by Florey, Chain, and Heatley (1939) Fleming, Florey, and Chain received Nobel Prize in 1945 for discovery and production of penicillin 3

4 4 Bacteriocidal Action of Penicillin

5 Later Discoveries Streptomycin, an antibiotic active against tuberculosis, was discovered by Selman Waksman (1944) Nobel Prize was awarded to Waksman in 1952 for this discovery by 1953 chloramphenicol, terramycin, neomycin, and tetracycline isolated 5

6 34.2 General Characteristics of Antimicrobial Drugs side effects undesirable effects of drugs on host cells narrow-spectrum drugs attack only a few different pathogens broad-spectrum drugs attack many different pathogens cidal agent - kills microbes static agent - inhibits growth of microbes 6

7 Disk Diffusion Tests disks impregnated with specific drugs are placed on agar plates inoculated with test microbe drug diffuses from disk into agar, establishing concentration gradient observe clear zones (no growth) around disks 7

8 8

9 34.4 Antimicrobial Drugs 1. inhibitors of cell wall synthesis 2. protein synthesis inhibitors 3. metabolic antagonists 4. nucleic acid synthesis inhibition 9

10 1. Inhibitors of Cell Wall Synthesis Penicillins Cephalosporines Vancomycin and Teicoplasmin 10

11 1. Inhibitors of Cell Wall Synthesis Penicillins Cephalosporines Vancomycin and Teicoplasmin 11

12 12

13 Transpeptidation

14 Penicillins most crucial feature of molecule is the b-lactam ring essential for bioactivity many penicillin resistant organisms produce b-lactamase (penicillinase) which hydrolyzes a bond in this ring 14

15 mode of action Penicillins blocks the enzyme that catalyzes transpeptidation (formation of cross-links in peptidoglycan) prevents the synthesis of complete cell walls leading to lysis of cell acts only on growing bacteria that are synthesizing new peptidoglycan 15

16 Vancomycin glycopeptide antibiotics vancomycin has been important for treatment of antibiotic-resistant staphylococcal and enterococcal infections previously considered drug of last resort so rise in resistance to vancomycin is of great concern 16

17 17 Vancomycin

18 2. Protein Synthesis Inhibitors Aminoglycosides Tetracyclines Macrolides (Erythromycin) Chloramphenicol 18

19 Aminoglycoside Antibiotics large family which all contain a cyclohexane ring and amino sugars bind to 30S ribosomal subunit and interfere with protein synthesis by directly inhibiting the process and by causing misreading of the messenger RNA resistance and toxicity 19

20 Tetracyclines all have a four-ring structure to which a variety of side chains are attached are broad spectrum, bacteriostatic combine with 30S ribosomal subunit inhibits bind of aminoacyl-trna molecules to the A site of the ribosome 20

21 Macrolides contain 12- to 22-carbon lactone rings linked to one or more sugars e.g., erythromycin broad spectrum, usually bacteriostatic binds to 23S rrna of 50S ribosomal subunit inhibits peptide chain elongation used for patients allergic to penicillin 21

22 22 Erythromycin, a Macrolide Antibiotics

23 Chloramphenicol now is chemically synthesized binds to 23s rrna on 50S ribosomal subunit and inhibits peptidyl transferase reaction toxic with numerous side effects so only used in life-threatening situations 23

24 3. Metabolic Antagonists Sulfonamides or Sulfa Drugs Trimethoprim 24

25 Sulfonamides or Sulfa Drugs structurally related to sulfanilamide, a paminobenzoic acid (PABA) analog PABA used for the synthesis of folic acid and is made by many pathogens sulfa drugs are selectively toxic for these pathogens because they compete with PABA for the active site of an enzyme involved in folic acid synthesis, resulting in a decline in folic acid concentration pathogen dies because folic acid is a precursor to purines and pyrimidines which are nucleic acid building blocks 25

26 26 Sulfa Drugs

27 Purine Biosynthesis initial products are ribonucleotides deoxyribonucleotides formed by reduction of nucleoside diphosphates or nucleoside triphosphates 27

28 4. Nucleic Acid Synthesis Inhibition a variety of mechanisms block DNA replication inhibition of DNA polymerase inhibition of DNA helicase block transcription inhibition of RNA polymerase drugs not as selectively toxic as other antibiotics because bacteria and eukaryotes do not differ greatly in the way they synthesize nucleic acids 28

29 Quinolones Synthetic drugs containing the 4- quinolone ring nalidixic acid was first quinolone to be synthesized (1962) generations of fluoroquinolones produced now act by inhibiting bacterial DNA-gyrase and topoisomerase II broad spectrum, bactericidal, wide range of infections 29

30 Quinolone Antimicrobial Agents 30

31 34.9 Drug Resistance an increasing problem once resistance originates in a population it can be transmitted to other bacteria a particular type of resistance mechanism is not confirmed to a single class of drugs microbes in abscesses or biofilms may be growing slowly and not be susceptible resistance mutants arise spontaneously and are then selected 31

32 32 Biofilm formation

33 33 Biofilm

34 Drug Resistant Superbug a methicillin-resistant Staphylococcus aureus (MRSA) that developed resistance to vancomycin this new vancomycin-resistant S. aureus (VRSA) was also resistant to most other antibiotics isolated from foot ulcers on a diabetic patient Acquired from conjugation with vancomycin-resistant enterococci (VRE) were isolated from same patient these drug resistant organisms are a serious threat to human health 34

35 35 Antibiotic Resistance Mechanism

36 약과건강 - 감염질환 Infectious Microbes, Host Defense and Mucosal Vaccines Sun-Young Chang, Ph.D. Lab of Microbiology College of Pharmacy Ajou University

37 The types of biological entities studied by microbiologists

38 The Course of an Infectious Disease 3

39 Proposed Chain of Avian Influenza (H5N1) Infection Swine flue (H1N1) 4

40 Transmission of Infectious Disease 5

41 Pathogen Transmission four main modes of transmission airborne contact vehicle vector borne 6

42 Airborne Transmission pathogen suspended in air and travels 1 meter droplet nuclei small particles (1 4 µm diameter) can remain airborne for long time can travel long distances usually propelled from respiratory tract of source organisms by sneezing, coughing, or vocalization dust particles also important route of airborne transmission 7

43 8

44 Contact Transmission coming together or touching of source/reservoir and host direct contact (person-to-person) physical interaction between source/reservoir and host e.g., kissing, touching, and sexual contact indirect contact involves an intermediate (usually inanimate) e.g., eating utensils, bedding droplet spread large particles (>5 µm) that travel <1 meter 9

45 Vehicle Transmission vehicles inanimate materials or objects involved in pathogen transmission common vehicle transmission single vehicle spreads pathogen to multiple hosts e.g., water and food fomites common vehicles such as surgical instruments, bedding, and eating utensils 10

46 Vector-Borne Transmission external (mechanical) transmission passive carriage of pathogen on body of vector no growth of pathogen during transmission internal transmission carried within vector harborage transmission pathogen does not undergo changes within vector biologic transmission pathogen undergoes changes within vector 11

47 Infectious Disease Transmission 12

48 Vaccines Edward Jenner ( ) Jonas Salk ( ) Louis Pasteur ( ) Albert Sabin ( ) Shibazaburo Kitazato ( ) Maurice Hilleman ( )

49 Immunity is Host Defense Virus Pathogen Influenza Super Bacteria (EHEC) Host Defense

50 Beginning of Vaccine and Immunology Edward Jenner (1747~1823) 1796: Edward Jenner creates the vacci ne against small-pox 1979: Small-pox is eradicated

51 Vaccine Power of Immunity Polio Vaccine Measles Vaccine (Cases) 40 Introduction of Vaccine 800 Incidence / Introduction of Vaccine (Year) (Year)

52 BCG for tuberculosis, Japanese encephalitis

53 Main Force of the Immune System NK NKT DC Mf TCTL TCTL NK Cells Antigen Presenting Cells Cytotoxic T Cells Th2 Th1 B B PC Helper T Cells B Cells Protection Strong Indi viduality Team Work Symbiosis

54 Microbial Pathogens Invade Host via Mucosal Surface Influenza (85nm) Inhalation Eschrichia coli 0157 (2-5mm) Ingestion HIV (100 nm) Sexual Contact

55

56 New Stream in Immunology Basis for the Paradigm of Mucosal Immunity Digestive and Respiratory Apparatus as Largest Immunological Orga ns Ingestion and Inhalation Skin Mucosa Immunocmpetent Cells 1-5x10 11 Cells Continuous Exposure to Outside Environment Microflora: 100 Trillion Organisms with 300 Spices (total 1kg of microflora per body)

57 Why do we need mucosal vaccine? <<<

58 Systemic vaccine vs Mucosal vaccine Systemic immune responses IgM IgG IgA Mucosal immune responses IgM IgG IgA

59 Systemic vaccine vs Mucosal vaccine Systemic immune responses Nasal Oral IgM IgG IgA Mucosal immune responses Needle-free Vaccine IgM IgG IgA

60 Mouse Study Method for Sublingual Delivery Mice were anesthetized by i.p. injection. Forceps were placed under the tongue and mouth was stretched open. Ag were administered by micropipette. (total volume is kept to < 10ml) Human Study Soluble type Ag Gel type Ag

61 Needle-free Transcutaneous Vaccination Skin Epidermis Dermis TCI Antigen (+Adjuvant) Langerhans cell (LC) CD11c + CD8 neg/low CD205 high CD11b + MHC II high Langerin Dermal dendritic cell (ddc) CD11c + CD8 neg/low CD205 inter CD11b high MHC II high Advantages as a vaccine route A needle-free method for delivering vaccines Safe and effective route in humans (Nat. Med., 2000) Protective immunity against mucosal challenge with toxin or live virus A novel strategy to induce both systemic and mucosal immune responses

62 Mucosal Immunity for Development of Needle-free Vaccine Painless Safety Efficacy

63

64 Proposed causes of dysbiosis of the microbiota

65 Vitamin on the immune system Skin Vitamin D 3 Small intestine (Gut) Vitamin A Epidermis Langerhans cell UVB Peripheral lymph node Vitamin D3 Vitamin A ADH RALDH Antigen Epithelium Mesenteric lymph node Naïve T cell Vitamin A Naïve B cell Dermal langerin + DC Dermis Venule Vitamin D3 1,25(OH) 2 D3 Blood 1,25(OH) 2 D3 Naïve T cell CCR10 Retinoic acid (RA) Lamina propria Venule M cell CD103 + DCs Blood RA Treg RA RA IgA ASC CCR9 α 4 β 7

66 Plus-Strand and Negative-Strand Viral Genomes 31

67 32

68 Viruses with Minus-Strand RNA Genomes (Group V) e.g., Influenza Virus 33

69 Negative-Strand Viruses cannot serve as mrna must bring into RNA-dependent RNA polymerase the newly synthesized plus strand serves as template for genome synthesis and mrna as well 34

70 Influenza Virus causative agent of the flu transmitted by inhalation or ingestion three types of viruses A, B, C seven to eight segments of linear RNA Hemagglutin binds host receptors Neuraminidase hydrolyzes mucus, cleaves virus from host receptor 35

71 Influenza Virus Life Cycle enters in endosome low ph causes conformational change in hemagglutin protein hydrophobic ends swing outward and fusion of membranes nucleocapsid released genome template for genome synthesis and mrna synthesis virus buds from host cell acquiring envelope 36

72 Influenza Virus Life Cycle 37

73 Tamiflu (Oseltamivir) anti-influenza agent a neuraminidase inhibitor though not a cure for influenza, has been shown to shorten course of illness 38

74 Anti-flu Drugs amantidine used to prevent influenza infections blocks penetration and uncoating of influenza virus Amantadine 39

75 Viruses with Single-Stranded RNA Genomes (Group VI-Retroviruses) HIV 40

76 Retroviruses convert ssrna into dsdna using reverse transcriptase dsdna integrates into host cell genome and serves as template for mrna synthesis and genome synthesis 41

77 Retroviruses - HIV human immunodeficiency virus (HIV) cause of acquired immunodeficiency syndrome (AIDS) global important pandemic ***A pandemic is an epidemic of infectious disease that is spreading through human populations across a large region; for instance multiple continents, or even worldwide. 42

78 HIV member of genus Lentivirus HIV-1 (most AIDS), HIV-2 HIV-1 enveloped virus two copies of RNA genome reverse transcriptase and integrase 43

79 44 HIV-1 Life Cycle

80 Anti-HIV Drugs reverse transcriptase (RT) inhibitors : azidothymidine (AZT), lamivudine (3TC) nucleoside RT inhibitors non-nucleoside RT inhibitors protease inhibitors: Ritonavir, saquinvir mimic peptide bond that is normally attacked by the protease fusion inhibitors prevent HIV entry into cells most successful are drug cocktails to curtail resistance : AZT, 3TC, ritonavir 45

81 How anti-hiv agents block HIV replication 46

82 Vision The effective control of poverty-related infectious diseases in developing countries through the accelerated and sustainable introduction of new-generation vaccines. Mission To combat infectious diseases through innovations in vaccine design, development and introduction, addressing the needs of people in developing countries.

83

84 감사합니다.