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Chapter 10

Antimicrobial drug

a chemical substance that destroys disease-causing microorganisms with minimal damage to host tissues

Chemotherapeutic agents

are compounds that destroy pathogenic microorganisms or inhibit their growth and are used in the treatment of diseases

Who developed the concept of chemotherapy to treat microbial diseases

Paul Ehrlich

Selective toxicity

chemotherapeutic agents that could kill pathogens without harming the host

What did Ehrlich use on syphilis

arsenic chemical

Who discovered the first antibiotic

Alexander Fleming

Who developed the first antibiotic for human use

Florey and Chain

antibiotics

microbial products or their derivatives that can kill susceptible microorganisms or inhibit their growth

three targets antibacteria drugs affect in prokaryotic cells

cell wall, ribosomes and metabolism

What three organisms are more difficult to treat

helminthic infections, fungal, protozoan,

Why are fungus, protozoa and helminthic infections more difficult to treat?

because they have eukaryotic cells

What do fungal infections drugs target?

The plasma membrane differences

What single infection is the MOST difficult to treat

Viral infection

drug that interferes with critical stages in the virus life cycle is

amantadine

2 drugs that inhibit the synthesis of virus specific nucleic acids

zidovudine, acyclovir

What inhibits virus replication

Interferon proteins

One thing an effective chemoterapeutic agent must have

selective toxicity

narrow spectrum drugs

affect only a select group of microbes

broad spectrum drugs

affect a large number of microbes

3 sources of bacteria

natural, semisynthetic or synthetic

2 general effects of antibiotics

static and cidal

When does superinfections occur

superinfections occur when a pathogen develops resistance to the drug being used or when normally resistant microbiota multiply excessively

3 places where drugs come from (italicized)

Streptomyces, Penicillum and Cephalosporium (mold)

bactericidal

killiing microorganisms

bacteriostatic

inhibiting their growth

All penicillins contain a _-____________ ____

B-Lactum Ring

Penicillins inhibit

peptidoglycan synthesis

natural penicillins are produced by

penicillum

natural penicillins are effective against

gram-positive cocci and spirochetes

Penicillinases aka

B-Lactamases

Penicillinases

bacterial enzymes that destroy natural penicillins

what produces penicillinases

staphylococcus species

MRSA are resistant to

oxacillin and methicillin

two types of semisynthetic penicillins

ampicillinn and methicillin

What does the monobactam aztreonam affect?

only gram-negative bacteria

Cephalosporins do two things

1) inhibit cell wall synthesis
2) are used against penicillin-resistant strains

Three examples of Polypeptide antibiotic

Bacitracin, Vancomycin, cycloserine

Bacitracin is used against

gram positive bacteria (Topical only)

Vancomycin and cycloserine are used for

killing drug resistant gram-positive staphylococci

What can be used against MRSA

Vancomycin and cycloserine

Three antimycobacterial antibiotics

Isoniazid (INH), Ethambutol, Streptomycil

4 antibacterial antibiotics

penicillin, penicillinase resistant penicillin, the monbactam aztreonam, polypeptide antibiotics

5 inhibitors of protein synthesis

chloramphenicol, aminoglycosides, tetracyclines, macrolides, oxamoldinones, antisense nucleic acids

2 types of aminoglycosides

streptomycin and gentamicin

3 things streptomycin is effective against

mycobacteria, plague and gram-negative bacteria

3 things GENTAMICIN IS EFFECTIVE AGAINST

PSEUDOMONAS, PROTEUS, E.COLI

how are tetracyclines produced

by some species of the Actinomycete genus, Streptomyces

Erythromycin is a type of

macrolide

what is the method of action of erythromycin

inhibit protein synthesis by binding to the bacterial ribosomes

what is erythromycin effective against (3)

gram positive bacteria, mycoplasma, few gram negative bacteria

what is oxamolidinones effective against

only gram positive bacteria

define antisense nucleic acids

designed to be complementary to specific RNA molecules of pathogens and thus block protein synthesis

Two things that cause damage to plasma membranes

polymyxin B and bacitracin

polymyxin is effective against

gram-negative bacteria

antimetabolites inhibit

metabolic pathways

How do antimetabolites work

they mimic a normal molecule

What ddo sulfonamides do

inhibit folic acid synthesis

another name for sulfonamides

sulfa drugs

Why are humans not effected by sulfonamides

they obtain the vitamin from food

3 things used as antiviral drugs

amantadine, rimantadine, weak organic bases

why are weak organic bases used as antiviral drugs

they can neutralize the acidic environment of phagolysosomes and thereby prevent viral uncoating

protease

an enzyme needed by HIV during its replication cycle

What does Isoniazid (INH) do

inhibits mycolic acid synthesis in mycobacteria

INH is administered with what to treat tuberculosis

rifampin or ethambutol

3 inhibitors of nucleic acid

rifamycin and quinolones and fluoroquinolones

what does Rifamycin (rifampin) inhibit

mRNA synthesis

What do quinolones and fluoroquinolones inhibit

DNA synthesis for treatment of urinary tract infections

What is bacterial gyrase for

needed for correct coiling of replicating bacterial DNA

disadvantage of DNA RNA inhibiting antibiotics

may interfere with human DNA and RNA and be toxic and develops antibiotic resistace

What do antiviral drugs target

the different stages of viral reproduction

how do you block attaachment of viruses to host cells

by peptide and sugar analogs of either attachment or receptor proteins

most drugs affect the...

nucleic acid synthesis of the virus

superbugs

Pathogens that are resistant to most antimicrobial agents

Cross resistance

typically occurs when drugs are similar in structure so the bacteria resists all of them

multiple resistance

resistance to more than one drug at a time

an example of synergism within drugs

penicillin and streptomycin are used for bacterial endocarditis. one damages the cell wall so the other can enter

an example of an antagonistic combination of drugs

penicillin (works on growing bacteria) and tetracycline (stops growth)

Three pathogens that have low-permeability membrane barriers

Pseudomonas aeruginosa, Mycobacterium tuberculosis, enterococcus

what kind of bacteria contain plasmids

gram negative

7 gram negative bacteria with R-factor plasmids

E. coli, Proteus, Serratia, Enterobacter, Salmonella, Shigella and pseudomonas

example of penicillinase bacteria

neisseria gonorrhoeae

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