Micro 22 Unit 3 Chapter 20

Front 1

Antimicrobial Drugs

Back 1

- drugs that may be synthetic or nonsynthetic and inhibit the growth of microbes within a host

Front 2

Chemotherapy

Back 2

- using drugs to treat disease caused by microbes

Front 3

Antibiotic

Back 3

a substance produced by microrganisms that in small amounts inhibits the growth of another microorganism

Front 4

Selective Toxicity

Back 4

- a drug that kills harmful microbes without damaging the host

- this is done by affecting some aspect of the pathogen that is not part of the host's physiology

Front 5

Spectrum of a Drug

Back 5

- range of organisms affected by a drug

Front 6

Broad Spectrum Drug

Back 6

- affects both Gram - and Gram + organisms

- more likely to affect an unidentified pathogen, but may damage beneficial flora and thus have a greater chance of superinfection (infection by another pathogen)

Front 7

Narrow Spectrum Drug

Back 7

- affects one or the other

Front 8

Superinfection

Back 8

- infection by another pathogen when beneficial flora are killed

- occurs when a pathogen develops resistance to the drug being used or when normally resistant microbiota multiply excessivey

Front 9

Synergism

Back 9

- combined effect of two drugs used at the same time is greater than the sum of their individual effects

ie. Damage to bacterial cell walls by penicillin makes it easier for streptomycin to enter

Front 10

Antagonism

Back 10

- combined effect of two drugs used at same time is less than the sum of their individual effects

ie. Tetracycline is bacteriostatic and interferes with the action penicillin.

Tetracyclin halts growth so penicillin can't do anything since the bacteria is not synthesizing peptidoglycan.

Front 11

Superbugs

Back 11

- bacteria that resistant to large numbers of antibiotics

1. MRSA

2. KPC

3. VRE

4. ESBLs

5. MRPA

Front 12

MRSA

Back 12

Methicillin Resistant Staphylococcus Aureus

Front 13

KPC

Back 13

Klebsiella Pneumonia Carabapenemase producing

Front 14

VRE

Back 14

Vancomycin Resistant Enterococcus

Front 15

ESBLs

Back 15

Extended Spectrum Beta Lactamase producing bacteria

Front 16

MRPA

Back 16

Multidrug-Resistant Pseudomonas Aeruginosa

Front 17

Name the microbes that produce the most antibiotics

Back 17

Streptomyces spp.

Front 18

Describe the problems of chemotherapy for viral, fungal, protozoan, and helminthic infections.

Back 18

- fungal, protozoan, and helminthic infections are more difficult to treat because these organisms have eukaryotic cells.

- viral infections are difficult because the pathogen is within the human host's cell and the virus is directing the human cell to make viruses.

Front 19

Identify five modes of action of antimicrobial drugs. (Study Foundationg Figure 20.2)

Back 19

1. Inhibition of Cell Wall Synthesis (penicillins)

2. Inhibition of Protein Synthesis (streptomycin)

3. Inhibition of Nucleic Acid Replication and Transcription (quinolones, rifampin)

4. Injury to Plasma Membrane (polymyxin B)

5. Inhibition of Essential Metabolite Synthesis (sulfanimide)

Front 20

Explain why drugs can be specific for bacteria (and not human cells or virions)

Back 20

This is because these drugs affect a physiologcial aspect of bacteria that hosts don't have.

1. Bacteria have 70s ribosomes, we have 80s ribosomes

2. they have Peptidoglycan in their cell walls, humans don't have cell walls

Front 21

Explain how a drug can be more toxic to a pathogen than to the host.

Back 21

This is because these drugs affect a physiological aspect of bacteria that hosts don't have.

same as above.

Front 22

Describe how Sulfa drugs inhibit microbial growth

Back 22

Sulfa drugs block the ability of folic acid to be synthesized. They do this by blocking PABA binding on the active site of enzymes. Folic acid is a precursor for bacteria to produce DNA/RNA .

Front 23

Action of Antimicrobial Drugs: Inhibiting Cell Wall Synthesis

Back 23

Penicillin - prevents the synthesis of intact peptidoglycan. Only actively growing cells are affected by these antiobiotics.

Penicillin has very little toxicity for host cells because we don't have peptidogylcan.

Front 24

Action of Antimicrobial Drugs: Inhibiting Protein Synthesis

Back 24

- Eukaryotes 80s ribosomes

- Prokaryotes 70s ribosomes allows for selective toxicity.

- Mitochondria contain 70s ribosomes also which may have adverse efects on the cells of the host.

- Streptomycin

Front 25

Action of Antimicrobial Drugs: Inhibiting Nucleic Acid Synthesis

Back 25

- some drugs have an extremely limited usefulness because they interfere with mammalian DNA and RNA also

- quinolones, rifampin

Front 26

Action of Antimicrobial Drugs: Inhibiting the Plasma Membrane

Back 26

- brings about changes in permeability of plasma membrane resulting in loss of important metabolites from the microbial cell

- combine with sterols in functional plasma membrane to disrupt the membrane

- act on fungal diseases

- polymyxin B

Front 27

Action of Antimicrobial Drugs: Inhibiting the Synthesis of Essential Metabolites

Back 27

- enzymatic acitvity can be compettitively inhibited by a substance (antimetabolite) that closely resembles the normal substrate for the enzyme

ie. suldanamine blocks PABA from binding and synthesizing folic acid (a coneznyme for the synthesis of amino acids)

Front 28

Penicillin (and how they work against bacteria)

Back 28

refers to a group of over 50 chemically related antibiotics containing a B-lactam ring called the nucleus.

They prevent the cross-linking of peptidoglycans which interferes with the construction of cell walls, mostly Gram +.

Front 29

Natural Penicillins

Back 29

Penicillins extracted from cultures of the mold Penicillium. It is useful against most staphylococci, streptococci, and several spirochetes.

Muscular Injection: rapid excretion

Oral: stomach dimishes its concentrations

Have long retention times in the body, but the concentration is so low that organisms must be very sensitive to it. They are susceptible to Penicillinases which cleave the B-lactam ring.

Front 30

Semysynthetic Penicillins

Back 30

Developed:
1. Interrupts synthesis of Penicillium and obtain only the common penicillin nucleus for use

2. Removal of side chains from completed natural molecules and then chemically add other chains that make them more resistant to penicillinase.

Front 31

The Diffusion Methods

Back 31

1. Disk Diffusion Method

2. E Test

sensitive, intermediate, or resistant

Front 32

Disk Diffusion Method

Back 32

1. Inoculate agar plate with pathogen

2. Place paper disks dipped in different disinfectants on surface of agar

3. Incubate

4. Compare Zones of Inhibition

Larger the zone = more senstivity to drug

Front 33

Disadvantages of the Diffusion Methods

Back 33

1. less soluable drugs may have a smaller zone of inhibtion

2. does not determine if drug is -cidal or -static

Front 34

E test

Back 34

enables a lab technician to estimate the minimal inhibitory concentration (MIC), the lowest antibiotic concentration that prevents visible bacterial growth

- a plastic-coated strip contains a gradient of antibiotic concentrations, and the MIC can be read from a scale printed on the strip

Front 35

Broth Dilution Test

Back 35

determines MIC (minimal inhibitory concentration) and MBC (minimal bactericidal concentration)

- sequence of decreasing concentrations of the drug in a broth, which is then inoculated with test bacteria

Front 36

Importance of the Broth Dilution Test

Back 36

- it avoids the excessive use of expensive antibiotics and minimizes the chance of toxic reactions that larger-than-necessary doses might cause

Front 37

Drug Resistance Develops in the Pathogens

Back 37

Some microbes develop drug resistance through mutation. Once they acquire this drug resistance, they can transfer these drug resistance genes to other bacteria through conjugation.

Each generation of bacteria become more drug resistance as people fail to take the proper medication. For example, if a person stops taking their medication after 2 days because they feel better even though it was prescribed for 4 then those few remaining drug resistance surviving bacteria will have a change to repopulate.

Front 38

Study Foundation Figure: 20.20 Bacterial Resistance to Antibiotics

Back 38

1. Blocking entry

2. Inactivation by enzymes

3. Alteration of target molecule

4. Efflux of antibiotic

Front 39

Acinetobacter baumanii

Back 39

- has developed resistance by means of all five of the major target sites illustrated in Foundation Figure 20.20

Front 40

Inactivation of the Drug

Back 40

d

Front 41

penicilllinase (beta-lactamase)

Back 41

Bacterial enzymes that destroy natural penicillins.

Semisynthetic penicillins are made to resist penicillinases/have a broader spectrum of activity.

Front 42

Drug Resistance Factors

Back 42

- carried by plasmids, or small segments of DNA called transposons, which can jump from one piece of DNA to another.

Front 43

Drug Susceptibility

Back 43

- the ability of a drug to affect a pathogen, the lack of resistance to a drug

Front 44

Drug Resistance

Back 44

- pathogen is not affected by a drug (opposite of drug susceptibility)

Front 45

Drug Susceptiblity Testing

Back 45

- determines which drugs might control an infection

- includes:

1. Kirby-Bauer Disk Diffusion Method

2. E test

3. Broth Dillution Test

Front 46

Synthetic Drugs

Back 46

- drug produced in lab/factory through chemical reactions

Front 47

Biosynthesis

Back 47

- production of a chemical by a living organism

Front 48

Explain antibiotic misuse as stated on page 572.

Back 48

1. Outdated/impure antibiotics

2. counterfeit antibiotics

3. Dose regimens are shorter than needed to eradicate infection, encouraging the survival of resistant strains of bacteria

4. unneccessary or inappropriate prescriptions

5. antibiotics used in animal feeds to promote growth increases drug resistance pathogens

Front 49

How can drug resistance be delayed?

Back 49

1. finishing full regimen of antibiotic prescriptions

2. never use left over antibiotics

3. healthcare workers should avoid unneccessary prescriptions and ensure that choice and dosage are appropriate for the situation

4. prescribe most specific antibiotic possible, instead of broad-spectrum antimicrobials

5. inserting needle into cotton to prevent aerosols from being inhaled

Front 50

Identify 3 Areas of Research on New Chemotherapeutic Agents

Back 50

1. peptides

2. bacteriocins

3. bacteriophages