wei-ping zhang, phd 张纬萍 dept. of pharmacology, school of medicine, zhejiang university...

Wei-Ping ZhangWei-Ping Zhang, PhD, PhD

张纬萍张纬萍Dept. of Pharmacology, Dept. of Pharmacology,

School of Medicine, Zhejiang UniversitySchool of Medicine, Zhejiang [email protected]@zju.edu.cn

2012.11.1

General ConsiderationsGeneral Considerationsfor for antimicrobial agentsantimicrobial agents

OverviewOverview

I. ChemotherapyI. Chemotherapy

II. Chemotherapeutic agentsII. Chemotherapeutic agents

III. Mechanisms under the action of III. Mechanisms under the action of chemotherapeutic agentschemotherapeutic agents

IV. Classification of antimicrobial agentsIV. Classification of antimicrobial agents

V. Bacterial ResistanceV. Bacterial Resistance

VI. Clinical pharmacology of antimicrobial VI. Clinical pharmacology of antimicrobial agentsagents

The Birth of Modern Chemotherapy: Dreams of a “Magic Bullet”

I. Chemotherapy

Louis Pasteur 1822-1895

Robert Koch 1843-1910

Rebecca Lancefield 1896-1981

Paul Ehrlich introduced an arsenic-containing chemical called salvarsan （阿斯凡纳明） to treat syphilis （梅毒） (1910).

–“Magic bullet” for treatment of syphilis

I. Chemotherapy

1928 Fleming discovers penicillin1928 Fleming discovers penicillin

History of Antimicrobial TherapyHistory of Antimicrobial TherapyI. Chemotherapy

1928

History of Antimicrobial TherapyHistory of Antimicrobial Therapy• 1928 Fleming discovers penicillin

• 1932 Domagk discovers sulfonamides

• 1940s Penicillin and streptomycin used widely, cephalosporins discovered

• 1947 Chloramphenicol discovered, first broad spectrum agent

• 1950s Tetracycline in use

• 1952 Erythromycin discovered (macrolides)

• 1956 Vancomycin used for penicillin-resistant S. aureus

• 1957 Kanamycin discovered (aminoglycosides)

• 1962 Nalidixic acid discovered (quinolones)

• 1980s Fluoroquinolones, broad spectrum cephalosporins

• 2000s Newer agents to combat resistant pathogens

I. Chemotherapy

History of Antimicrobial TherapyHistory of Antimicrobial Therapy

I. Chemotherapy

Endless way ………………

Superbug……drug resistance

MRSAMRSA ，， NAM-1NAM-1

Pharm

acokineti

Pharm

acokineti

cscs

Adverse

Adverse

effects

effects

pathogenicitypathogenicity

ImmunologicalImmunologicalresponsesresponses

Ther

apeu

tic

Ther

apeu

tic

Effec

ts

Effec

ts

Res

ista

nce

Res

ista

nce

Host FactorsHost Factors ：： patient’s age, patient’s age, gender, constitgender, constitution, hepatic, ution, hepatic, renal function renal function

II. Chemotherapeutic agents


Antimicrobial drugsAntimicrobial drugs

Antibacterial drugsAntibacterial drugs

Antifungal drugsAntifungal drugs

Antiviral drugsAntiviral drugs

Antiparasitic durgsAntiparasitic durgs

Antineoplastic / anticancer drugsAntineoplastic / anticancer drugs

Ideal antimicrobial drugsIdeal antimicrobial drugs

High sensitivityHigh sensitivity Nontoxic or low-toxic (safety)Nontoxic or low-toxic (safety) NonresistanceNonresistance Satisfied pharmacokinetic propertiesSatisfied pharmacokinetic properties Good priceGood price


Antibacterial drugs (Antibacterial drugs ( 抗菌药抗菌药 ))

kill bacteria and arresting its growthkill bacteria and arresting its growth

antibioticsantibiotics and and synthetic antimicrobisynthetic antimicrobi

al agentsal agents such as sulfonamides such as sulfonamides(( 磺胺磺胺类类 )) and quinolones and quinolones (( 喹诺酮类喹诺酮类 ))..


AntibioticsAntibiotics （抗生素）（抗生素） Produced by various species of miProduced by various species of mi

croorganisms (bacteria, fungi , acticroorganisms (bacteria, fungi , acti

nomycetes) and semi-syntheticnomycetes) and semi-synthetic

Suppress the growth of other micrSuppress the growth of other micr

oorganisms.oorganisms.


Antibacterial spectrumAntibacterial spectrum （抗菌谱）（抗菌谱）• Narrow?Narrow?• Broad?Broad?

Chemotherapetic index (CI)Chemotherapetic index (CI) （治疗指（治疗指数）数）

• CI= LDCI= LD50 50 / ED/ ED50 50

• CI= LDCI= LD5 5 / ED/ ED9595


Bacteriostatic drugs Bacteriostatic drugs （抑菌药）（抑菌药）inhibit the growth of microorganisms inhibit the growth of microorganisms

e.g. Sulfonamides, Tetracyclinee.g. Sulfonamides, Tetracycline

Bactericidal drugs Bactericidal drugs （杀菌药）（杀菌药）• kill microorganismskill microorganisms

e.g. Penicillin, Aminoglycosidese.g. Penicillin, Aminoglycosides


Bactericidal vs Bacterostatic


Minimum inhibitory concentration Minimum inhibitory concentration (MIC)(MIC)

最低抑菌浓度最低抑菌浓度

Minimum bactericidal concentration Minimum bactericidal concentration (MBC)(MBC)

最低杀菌浓度最低杀菌浓度

Post antibiotic effect Post antibiotic effect (PAE) (PAE)

抗生素后效应抗生素后效应

Resistance Resistance （（耐药性耐药性））

Cross Resistance Cross Resistance （（交叉耐药性交叉耐药性））

First expose effect First expose effect （（首次接触效应首次接触效应））



最低抑菌浓度最低抑菌浓度

最低杀菌浓度最低杀菌浓度

Incubate 18 to 24 hr at 37℃

Measure Measure diameters ofdiameters ofnongrowthnongrowthzoneszones

Disk diffusion method for testing bacteria for susceptibility to specific antimicrobial drugs. Disk diffusion method for testing bacteria for susceptibility to specific antimicrobial drugs.


III. Mechanism of action

1. Inhibit synthesis of bacterial cell walls1. Inhibit synthesis of bacterial cell walls

2. Affecting permeability of cell membrane a2. Affecting permeability of cell membrane a

nd leading to leakage of intracellular compnd leading to leakage of intracellular comp

oundsounds

3. Inhibit protein synthesis3. Inhibit protein synthesis

4. Affect bacterial nucleic acid metabolism4. Affect bacterial nucleic acid metabolism

5. Block essential enzymes of folate metabol5. Block essential enzymes of folate metabol

ism ism


1.1. Inhibiting synthesis of bacterial cell wallsInhibiting synthesis of bacterial cell walls e.g. penicillins, e.g. penicillins, -lactams-lactams



乙酰胞壁酸乙酰胞壁酸 -5-5 肽肽乙酰胞壁酸乙酰胞壁酸 -5-5 肽肽

UDP-UDP- 乙酰葡萄糖胺乙酰葡萄糖胺

2. Affecting permeability of membrane2. Affecting permeability of membrane

Ionic- sorbent （离子吸附剂离子吸附剂） e.g. Aminoglycosides e.g. Aminoglycosides （氨基糖苷类）（氨基糖苷类）

Binding to ergosterol Binding to ergosterol （麦角固醇）（麦角固醇） e.g. Nystatin (e.g. Nystatin ( 制霉菌素制霉菌素 ))

Amphotericin BAmphotericin B （（两性霉素两性霉素））

Cationic detergentCationic detergent

e.g. polymyxinse.g. polymyxins （多粘菌素）（多粘菌素）


Lipopoly-saccharide

Outermembrane

Peptidoglycan

Cytoplasmicmembrane

polymyxinspolymyxins

2. Affecting permeability of membrane 2. Affecting permeability of membrane


Ribosomal structure

• Bacteria 30S + 50S 70S30S subunit

• binds mRNA in initiation complex• holds growing peptide chain

50S subunitaccepts / translocates charged tRNAs

• "A" site --> Aminoacyl-tRNA (acceptor) site • "P" site --> Peptidyl-tRNA (donor) site

• Mammals 40S + 60S 80S

3. Inhibiting protein synthesis 3. Inhibiting protein synthesis


3. Inhibiting protein synthesis3. Inhibiting protein synthesis

PP AA


3. Inhibiting protein synthesis3. Inhibiting protein synthesis

PP AA


氨基糖苷类四环素

大环内酯类

氨基糖苷类

氯霉素林可霉素

4. Affecting bacterial nucleic acid metabolism4. Affecting bacterial nucleic acid metabolism

quinolones

(-)(-)

Break back Break back segmentsegment

(+)(+)

(-)(-)


Rifampicin ( 利福平 ): inhibit DNA-dependent RNA polymerase

Ridarabine ( 阿糖腺苷 ), Ganciclovir ( 更昔洛韦 ) inhibit DAN polymerase

Pteridine + PABA

Blocked by sulfonamides

Dihydropteroic acid

Dihydrofolic acid

glutamate

Tetrahydrofolic acid

Blocked by trimethoprim

NADPH

NADPH

Dihydropteroatesynthase

Dihydrofolatereductasease

5. block essential enzymes of folate metabolism5. block essential enzymes of folate metabolism


蝶啶对氨基苯甲酸

二氢蝶酸

甲氧苄啶

According to bio-activityAccording to bio-activity

Anti GAnti G++ antibiotic antibiotic Anti GAnti G-- antibiotic antibiotic Broad-spectrum antibioticBroad-spectrum antibiotic Anti mycobacterium (Anti mycobacterium ( 分支杆菌分支杆菌 ) antibiotic) antibiotic Anti anaerobe Anti anaerobe （厌氧菌）（厌氧菌） antibioticantibiotic -lactamase inhibitor -lactamase inhibitor （（内酰胺酶抑制内酰胺酶抑制

剂）剂）

IV. Classification of antimicrobial drugsIV. Classification of antimicrobial drugs

According to the chemical structureAccording to the chemical structure ：：1.1. -lactams (-lactams (-- 内酰胺类）；内酰胺类）； PenicillinsPenicillins （青霉（青霉

素类）；素类）； CephalosporinsCephalosporins （头孢菌素类）（头孢菌素类） ;;

2.2. Aminoglycosides(Aminoglycosides( 氨基糖苷类氨基糖苷类 ););

3.3. MacrolidesMacrolides （大环内酯类）（大环内酯类） ; Lincosamides; Lincosamides（林可胺类）（林可胺类） ;Vancomycins;Vancomycins （万古霉素类）（万古霉素类）

4.4. TetracyclinesTetracyclines （四环素类）；（四环素类）； Chloramphenicol (Chloramphenicol ( 氯霉素氯霉素 ))

Antimicrobial drugsAntimicrobial drugs -Characteristics -Characteristics


5. Quinolones (5. Quinolones ( 喹诺酮类喹诺酮类 ))

6. Sulphonamides (6. Sulphonamides ( 磺胺类磺胺类 ))

7. Nitrofurans (7. Nitrofurans ( 硝基呋喃类硝基呋喃类 ))

8. Antimycobacterial agents (8. Antimycobacterial agents ( 抗结核分抗结核分支杆菌类支杆菌类 ) )

9. others: 9. others:

OxazolidinonesOxazolidinones （恶唑烷酮类）（恶唑烷酮类） StreptograminsStreptogramins （链阳菌素类）（链阳菌素类）


Intrinsic resistanceIntrinsic resistance – – Inherent featuresInherent features ，， usually expressed by usually expressed by chromosomal geneschromosomal genes

Acquired resistanceAcquired resistance – – Emerge from previously sensitive bacterial Emerge from previously sensitive bacterial populationspopulations – – Caused by mutations in chromosomal Caused by mutations in chromosomal genesgenes – – Or by acquisition of plasmids or Or by acquisition of plasmids or transposonstransposons

V. Bacterial Resistance

• The drug is not active.The drug is not active.

• The target is altered.The target is altered.

• The drug does not reach its target. The drug does not reach its target.

Bacterial Resistance- MechanismsBacterial Resistance- Mechanisms


Production of aminoglycoside-modifying Production of aminoglycoside-modifying enzymes andβ-lactamase;enzymes andβ-lactamase;

1.The drug is not active.1.The drug is not active.


2.The target is altered2.The target is altered

Mutation of the natural targMutation of the natural targ

et (quinolone resistance)et (quinolone resistance)

Substitution with a resistanSubstitution with a resistan

t alternative to the native, st alternative to the native, s

usceptible target (methicilliusceptible target (methicilli

nn （甲氧西林）（甲氧西林） resistance) resistance)


Target modification (riTarget modification (ri

bosomal protection tybosomal protection ty

pe of resistance to mape of resistance to ma

crolides and tetracyclicrolides and tetracycli

nes)nes)

2.The target is altered2.The target is altered


Absence, mutation or lAbsence, mutation or l

oss of the appropriate oss of the appropriate

transportertransporter or or porins porins

(( 膜孔蛋白）膜孔蛋白）

3.The drug does not reach its target 3.The drug does not reach its target


Active efflux system Active efflux system (( 主主动排出系统动排出系统 ) )

Efflux transporterEfflux transporter（转运子）（转运子）

Accessory protein Accessory protein （附加蛋白）（附加蛋白）

Outer membrane chaOuter membrane channelnnel （外膜蛋白）（外膜蛋白）

3.The drug does not reach its target 3.The drug does not reach its target


Active efflux systemActive efflux system （主动排出系统）（主动排出系统）

transportertransporter Accessory proteinAccessory protein

Outer membraneOuter membranechannelchannel


Mutations Mutations 突变突变 Transduction Transduction 转导转导 Transformation Transformation 转化转化 Conjugation Conjugation 接合接合

The transfer of Resistance genes The transfer of Resistance genes


From human From human human human

From bacteria From bacteria bacteria bacteria

IntracellularIntracellular

Mutations Mutations 突变突变


May occur in the gene encodingMay occur in the gene encoding

The target proteinThe target protein

A protein involved in drug transportA protein involved in drug transport

A protein important for drug activation A protein important for drug activation

A regulatory gene or promoter affecting A regulatory gene or promoter affecting expression of the target, a transport protein, expression of the target, a transport protein, or an inactivating enzyme or an inactivating enzyme

Mutations Mutations 突变突变


Transduction Transduction 转导转导


•Transformation Transformation 转化转化 •Conjugation Conjugation 接合接合


Multi-drug resistance Multi-drug resistance (MDR) (MDR)

1.1. Methicillin-resistant staphylococcus Methicillin-resistant staphylococcus aureus, MRSAaureus, MRSA

甲氧西林耐药金黄色葡萄球菌甲氧西林耐药金黄色葡萄球菌

Methicillin-resistant coagulase Methicillin-resistant coagulase negative staphylococci, MRCNS negative staphylococci, MRCNS 甲氧西林凝固酶阴性葡萄球菌甲氧西林凝固酶阴性葡萄球菌

PBP-2a PBP-2a （（ a 78kD new PBa 78kD new PBPP ））


Multi-drug resistance MDR Multi-drug resistance MDR

2.2. Penicillin-resistant streptococcus pneumoniae, Penicillin-resistant streptococcus pneumoniae,

PRSPPRSP ，，青霉素耐药肺炎链球菌青霉素耐药肺炎链球菌• PBP-1a, PBP-2a, PBP-2x, PBP-2b PBP-1a, PBP-2a, PBP-2x, PBP-2b （（ 78-100 kD78-100 kD ））• Active efflux system Active efflux system （（ express mef(A)express mef(A) 对大环内酯对大环内酯

类）类）

3.3. Vancomycin-resistant Enterococcus, VREVancomycin-resistant Enterococcus, VRE

万古霉素耐药肠球菌万古霉素耐药肠球菌• PBP avidity ↓PBP avidity ↓

• van-A, van-B, van C-1, van C-2, van D, van Evan-A, van-B, van C-1, van C-2, van D, van E


4. The 34. The 3rdrd generation-cephalosporins -resistant generation-cephalosporins -resistant

• Extended spectrumβ-lactamases, ESBLExtended spectrumβ-lactamases, ESBL

超广谱超广谱 β- β- 内酰胺酶内酰胺酶 • Class I chromosone mediated β-lactamases Class I chromosone mediated β-lactamases

II 类染色体介导的类染色体介导的 β- β- 内酰胺酶内酰胺酶 • E.g. E.g. 大肠埃希菌、克雷伯肺炎杆菌、阴沟肠杆菌大肠埃希菌、克雷伯肺炎杆菌、阴沟肠杆菌



5.5. Carbapenem (Carbapenem ( 碳青霉烯碳青霉烯 ) –resistant) –resistant ：对亚胺：对亚胺培南的铜绿假单胞菌敏感培南的铜绿假单胞菌敏感

• OprD porinOprD porin• Metalβ-lactamases Metalβ-lactamases （金属（金属 β- β- 内酰胺酶内酰胺酶））6. Quinolone-resistant escherichia coli6. Quinolone-resistant escherichia coli （大肠（大肠

埃希菌）埃希菌） , AREC, AREC• Active efflux systemActive efflux system• Cross-resistanceCross-resistance



superbug or super bacterium

Estimated TB incidence rates, 2009

VI. Clinical pharmacology of antimicrobial agents

Treatment with the drug resistence

Antimicrobial agents combinationsAntimicrobial agents combinations

According to their actions, According to their actions, antimicrobial agantimicrobial agentsents can be classified: can be classified:

① ① bactericidalbactericidal agents for growing bacteria agents for growing bacteria ② ② bactericidalbactericidal agents for resting bacteria agents for resting bacteria ③ ③ fast bfast bacteriostatic acteriostatic agents agents ④ ④ slow bslow bacteriostatic acteriostatic agentsagents



According to their actions, According to their actions, antimicrobial agantimicrobial agentsents can be classified: can be classified:

① ① bactericidalbactericidal agents for growing bacteria agents for growing bacteria ② ② bactericidalbactericidal agents for resting bacteria agents for resting bacteria ③ ③ fast bfast bacteriostatic acteriostatic agents agents ④ ④ slow bslow bacteriostatic acteriostatic agentsagents

① ①+ : synergism②+ : synergism② ① ①+ : antagonism③+ : antagonism③ ① ①+ : addition or indifference④+ : addition or indifference④ ③ ③+ : addition ④+ : addition ④


• Two is better than one?Two is better than one?– Empiric therapyEmpiric therapy– Polymicrobial infectionPolymicrobial infection– Increase efficacy--synergismIncrease efficacy--synergism– Prevent emergence of resistancePrevent emergence of resistance

• Combination therapyCombination therapy– Mycobacterium tuberculosisMycobacterium tuberculosis– HIVHIV– Pseudomonas aeruginosaPseudomonas aeruginosa(( 铜绿假单胞菌铜绿假单胞菌 ))– ? Invasive aspergillosis? Invasive aspergillosis （（侵入性曲霉菌病侵入性曲霉菌病））



First-line agentsFirst-line agents

Isoniazid(INH,Isoniazid(INH, 异烟肼异烟肼 ))

Rifampin(Rifampin( 利福平利福平 ))

Pyrazinamide(Pyrazinamide( 吡嗪酰吡嗪酰胺胺 ))

Ethambutol(Ethambutol( 乙胺丁醇乙胺丁醇 ))

Streptomycin(Streptomycin( 链霉素链霉素 ) )

Second-line agentsSecond-line agents

Para-aminosalicylicPara-aminosalicylic

(( 对氨水杨酸对氨水杨酸 ))

Ethionamide(Ethionamide( 乙硫异烟乙硫异烟胺胺 ))

Amikacin(Amikacin( 阿米卡星阿米卡星 ))

Capreomycin(Capreomycin( 卷曲霉素卷曲霉素 ))

FluoroquinolonesFluoroquinolones

(( 氟喹诺酮类氟喹诺酮类 ))


wei-ping zhang, phd 张纬萍 dept. of pharmacology, school of medicine, zhejiang university...

Documents