Microbiology Ch 20 Antibiotics and Antimicrobial drugs

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By: Sheri Sannella
Created: 2011-10-30
Size: 60 flashcards
Views: 78

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First antibiotic discovered; by whom

Penicillin
Fleming

Define antibiotic

Chemical naturally produced by one microorganism that kills/inhibits another. Can also be a semi synthetic antibiotic, which is a naturally occurring antibiotic that has been slightly chemically altered.

What was Fleming growing on the petri dish that was affected by the penicillin?

Staphylococcus aureus

Of all the antimicrobial drugs, this category is the largest

Antibiotics

Define antimicrobial

Drug/substance that are effective against ALL microbes

How does an antimicrobial differ from an antibiotic?

An antibiotic is only effective against bacteria; antimicrobial is effective against all microbes

Difference b/w antibiotic drugs and disinfectants/antiseptics?

Antibiotics are taken INTO the body. The others are for SURFACES

NAme 2 broad spectrum antibiotics and what they treat

Tetracycline: G-, G+, chlamydia, ricketsias (both of these are intracellular)
Streptomyocin: mycobacterium, G- (causes deafness)

Name 2 narrow spectrum antimicrobial medicines

Isoniazid: Mycobacterium
Acyclovir: viruses

name a negative and a postive in using a broad spectrum antibiotic

Neg: not only kills the pathogen but also your normal flora, setting you up for another infection
Pos: you don't have to know the exact cause of the infection

Name a negative and a postive in using a narrow spectrum antibiotic

Neg: you have to know the exact cause of the infection
Pos: it won't wipe out your normal flora, only kills the specific pathogen

2 categories of microbes that naturally produce antibiotics. Name specific genus and the antibiotic they produce

1. Bacteria: Bacillus- produces bacitracin
Streptomyces- produces streptomyocin, erythromycin, tetracycline

2. Fungi: Cephalosporium- produces cephalothin
Penicillium- produces penicillin

Antibiotics need to do these 3 things

1. Kill/inhibit pathogen, not host
2. Low side effects in host, high toxicity in pathogen
3. Exploit the differences b/w host and pathogen

5 specific ways antibiotics work

1. Inhibit cell wall synthesis
2. iNhibit protein synthesis
3. Inhibit nucleic acid synthesis
4. Increase permeability of plasma membrane
5. Inhibit metabolic pathways

Name 3 antibiotics that interfere in cell wall synthesis

Penicillin: prevents cross bridges from forming
Cephalosporin: interferes with production of peptidoglycan
Isoniazid: interferes with production of mycolic acid (mycobacteria)

Name 4 antibiotics that interfere with protein synthesis/translation

Erythromycin
Tetracycline
Streptomyocin (toxic: causes deafness)
Chloramphenical (toxic: stops blood cell production but is needed to treat Typhoid Fever)

Name an antibiotic that increases permeability of the plasma membrane

Polymyxin B (topical ONLY....very toxic)

Name 2 antibiotics that inhibit nucleic acid synthesis

Quinolones: inhibit production of DNA/replication (toxic)
Rifampin: inhibit production of RNA/transcription (toxic) used to treat TB

Name 2 antibiotics that inhibit metabolic pathways

SMZ, TMP: compete with PABA in folic acid pathway
Low toxicity since we don't have a folic acid pathway

Example of 2 antibiotics that are antagonistic to each other

tetracycline given first, then penicillin

Example of 2 antibiotics that are synergistic to each other

SMZ, TMP

Define prophylaxis and 3 situations when it is needed

Antibiotics given BEFORE an infection as a preventative measure
1. Before colon/appendix surgery
2. Before dental work if you have heart valve condition (S. aureus in mouth will get into blood and attach to heart valves)
3. AIDS patients to prevent infections which in the past used to kill them

4 factors in the pathogens environment affecting antimicrobial activity/effectiveness

1. Metabolic state of pathogen: has it slowed down its metabolic activity?
2. Interfering substances: binding proteins in blood, acid in stomach reduce effectiveness
3. Location of pathogen: is it an intracellular pathogen hiding in host cell, evading drugs?
4. Distribution of drug through different tissues: if microbe is in brain, and IV won't work since it won't cross the blood brain barrier.
*remember you want MILD not WILD pathogens

3 factors regarding the concentration of antibiotics and their effectiveness

1. Absorbtion, inactivation, excretion: will it be absorbed, inactivated by the liver, excreted by the kidneys?
2. Distribution of drug: systemic will not have as high of a concentration as a local or topical distribution
3. Dosage fluctuations: proper concentration must be maintained to reduce population by 90%
*remember ADD=concentration

3 categories of antiviral drugs

1. Nucleotide analogs
2. Enzyme inhibitors
3. Interferons

2 examples of nucleotide analogs

AZT
Acyclovir

Antifungals will target these 2 things

Ergosterol, chitin

Where specifically in fungus is ergosterol found? Chitin?

plasma membrane, cell wall

Why are antifungals so toxic to humans?

Because they are eukaryotes just like us, therefore our cells are very similar with only a few differences (like ergosterol and chitin)

Name 3 antifungal medicines

Amphotericin B, Imidazole, Griseofulvin

5 ways microbes defend themselves against antibiotics/antimicrobials

1. change receptor for the drug
2. change target site (reshape their 70S ribosomes)
3. change metabolic pathways
4. produce enzymes to break down drug: beta lactamase breaks down penicilllin
5. multi drug resistance pump

7 reasons drug resistance has developed

1. over prescribed
2. people insist on them from doc
3. improper dosage: not taking all prescribed
4. used in animals which we ingest
5. no prescription needed in other countries
6. nocosomial infections due to chronically infected bringing their resistant bacteria into hospitals
7. overuse of antibiotic soaps with triclosan

2 antibiotic sensitivity tests

Kirby Baur
Minimal Inhibitory Concentration

In order for an antibiotic to be effective it must reduce pathogen population by _____%

90%

Staphylococcus first treated with this antibiotic _________, then after it became resistant it was treated with _______, now ___________is used.

Penicillin
Methycillin
Vancomyocin

MRSA stands for

Methycillin resistant Staphylococcus aureus

This antibiotic, which inhibits RNA synthesis, is used to treat TB

Rifampin

This antibiotic, which inhibits protein synthesis, is used to fight Typhoid Fever.

Chloramphenical

Topical antibiotics, like Polymyxin B, do THIS to the bacteria

Increase their plasma membrane permeability

This organ is responsible for detoxification

Liver

NAme a bacteria that can remain dormant on a dry surface for a very long time

Mycobacteria tuberculosis

Name a virus that becomes inactivated as soon as it touches a dry surface

HIV

If someone had meningitis, what would be the best way to deliver the antibiotics?

Needs to be put into the cerebrospinal fluid (epidural)

If someone has necrotic tissue, would it be best to give them IV antibiotics or topical?

Necrotic tissue lacks circulation so IV wouldn't work. Topical would be necessary.

Name two intracellular bacterial species

Chlamydia, Ricketsias

These two antifungals effect ergosterol production

Amphotericin B
Imidazole

The danger of streptomyocin is that it can cause

Deafness

Why are the antibiotics that inhibit protein synthesis potentially toxic to us?

They bind to 70S ribosomes, which we have in our mitochondria.

This antiviral is used to treat HIV. What "category" of antivirals is it in?

AZT, nucleotide analog

AZT, used to treat HIV, is a nucleotide analog which looks like

Thymine

Acyclovir, an antiviral, is a nucleotide analog which looks like

Guanine

Nucleotide analogs are SIMILAR to nucleotides this way but different in this way

similar in nitrogen base, different in their sugars and the phosphate group

T/F Interferons help us to feel better since they are fighting off viruses

False: they do fight viruses but they actually cause us to feel sick. This is to force us to rest.

How do nucleotide analogs combat viruses?

Cause mistakes as the viral genetic info is copied

This enzyme inhibitor antiviral is important in controlling HIV infections

Reverse Transcriptase Inhibitor

This antibiotic prevents DNA replication

Quinolones

This antibiotic prevents transcription

Rifampin

These 4 antibiotics prevents translation

erythromycin
tetracycline
streptomycin
chloramphenical

What is replication, transcription, translation?

Replication: DNA copies itself prior to cell division
Transcription: DNA copied onto mRNA strand for protein synthesis
Translation: mRNA strand is "read" by ribosomes to produce a polypeptide chain

This antibiotic, used to treat Typhoid Fever, is very toxic for it can inhibit hematopoiesis. Name the antibiotic and define hematopoiesis.

Chloramphenical
blood cell production

About this deck

By: Sheri Sannella
Created: 2011-10-30
Size: 60 flashcards
Views: 78

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj