Chapter 12, Microbiology

Paul Ehrlich

Scientist that theorized that there could be a “magic bullet” chemical that would kill microbes without harming the host cells.

Selective Toxicity

The property of destroying the infective agent without harming the host’s cell.

Chemotherapy

The application of chemicals to treat a disease.

Alexander Flemming

Scientist that discovered a mold called Penicillium inhibited the growth of Staphylococcus aureus.

Antibiotics

A substance produced by microbes that inhibits the growth of other microorganisms.

WWII

The war that saw the greatest advances in antibiotics.

First sulfa drug; Protecil Red

The drug that the Germans came up with during WWII.

Penicillin

Antibiotics that they Americans/British developed during WWII.

Prophylaxis

The use of a drug to prevent imminent infection of a person at risk.

Antimicrobials

All inclusive term for any antimicrobial drug regardless of what type of microbe it targets.

Antibiotics

A substance that is produced by natural metabolic processes of some microbes, that can inhibit or destroy microbes.

Narrow-Spectrum Drugs

An antimicrobial that is effective against a limited group of microbes.

Broad-Spectrum

An antimicrobial drug that is effective against a wide range of microbes.

Streptomyces

Genus produces almost half of known antibiotics.

Bacillus Subtilis

Species produces bacitracin.

Penicillium & Cephalosporium

Two mold genera that produce antibiotics as well.

Kirby-Bauer Technique

Name of the drug susceptibility technique measuring technique that involves inoculating a plate with a test bacterium and then placing small discs containing antibiotics on the bacterial lawn.

Zone of Inhibition

The area of no growth around the disc.

More sensitive

Bigger the zone of inhibition means the bacterium is more…

Resistant

Smaller the zone means the bacterium is more…

Antibiogram

A bacterium’s profile of antimicrobial sensitivity.

Minimum Inhibitory Concentration (MIC)

The smallest concentration (HIGHEST DILUTION) of a drug that still inhibits visible growth.

Serial Dilution

What has to be made of the antimicrobial drug that determines the MIC.

Smallest Effective Dosage

What the MIC helps you determine.

Therapeutic Index

The ratio of the dose of the drug that is toxic to humans compared to its effect (therapeutic) dose.

TI of 1.1

Which is riskier, TI of 1.1 or TI of 10?

Selective Toxicity

Property of antimicrobial drugs means they kill or inhibit microbial cells without simultaneously damaging host tissues.

Penicillins

Group of drugs that demonstrates selective toxicity by blocking the synthesis of peptidoglycan in the cell wall of bacteria, something that vertebrate cells don’t have.

Penicillins

Group of antibiotic which can be obtained naturally or synthesized in the lab, inhibit the formation of peptidoglycan, causing bacterial cells to lyse.

Beta Lactam Ring

Penicillins that consists of thiazolidine ring, a variable side chain and…

Cephalosporium Acremonium

Group of antibiotics that was originally isolated from mold in the 1940s, has a similar mode of action to penicillin, and also has a beta lactam ring.

Bacitracin, Isonidzid, Vancomycin

Three other drugs that target the cell wall.

Aminoglycoside

Group of antibiotics, consisting of amino sugars, blocks the 30S portion of bacterial ribosomes, which are different than our 80S ribosomes.

Mitochondrial; Ribosomes

Eukaryotic organelles might be affected by thee drugs and why.

Tetracyclines

Broad-spectrum drug class of antibiotics that binds to the 70S ribosomes and blocks tRNA, but has GI side effects and can discolor teeth in children.

Macrolides

Azithromycin and Erythromycin belong to this class of antibiotics, which is named after a ring they possess in their chemical structure, and also blocks protein synthesis by binding to the 70S ribosomes.

Sulfamides

Class of drugs that was the first modern antimicrobial drugs, are synthetic, and works by preventing the production of folic acid in bacteria by mimicking the precursor PABA, (acting as a competitive inhibitor)

Human only ingest folic acid.

Why don’t sulfa drugs impact our folic acid production.

Fluoroquinolones

Broad-specturm group inhibits bacterial DNA gyrase, the enzyme that relaxes DNA supercoiling, and includes Cipro and Levaquin

Rifampin

Antibiotic works by inhibiting bacterial RNA polymerase enzymes, inhibiting transcription.

Polymyxins

Group of narrow-spectrum antibiotics interacts with membrane phospholipids, distorting the cell surface and causing leakage.

Daptomycin

Antibiotic is a lipopeptide made by streptomyces, which has effectiveness against gram-positive bacteria and biofilms.

Biofilms

The form that can make bacteria 1000 times more resistant to antimicrobials.

Quorum Sensing Pathways

New techniques in the treatment of biofilm infections involve interrupting what kind of pathways.

Barring penetration of virus into the host cell.

How antiviral drugs like Amantadine, Tamiflu, and Fuzeon work.

Guanine analog, does not allow the virus to replicate its DNA.

What king of drug that acyclovir is and how it works.

Prevents reverse transcriptase from making HIV viral DNA.

What HIV enzymes that nucleoside analogs inhibit?

Protease Inhibitors

Viral enzyme that can be inhibited to prevent the maturation of viral particles by not allowing the viral proteins to be cleaved from each other.

Interferons

Glycoprotein that is a natural part of the antiviral immune response and has been given in the past as an antiviral therapy.

Drug Resistance

The adaptive response in which microbes tolerates an amount of drug that would ordinarily be inhibitory.

Intrinsic

Type of resistance that is already possessed by the microbe, possibly because they must be resistant to antibiotics that they produce themselves.

Acquired

Type of resistance that is gained to a drug to which the microbe was previously sensitive to.

Spontaneous Mutation

Drug resistance that evolve through changes in DNA called spontaneous…?

Large Microbial Populations

Even though the chance of mutation being advantageous is small, what property of microbial populations makes these mutations more likely to occur.

Resistance (R) Factors

Plasmids that can spread drug resistance through horizontal transfer such as conjugation, transformation, or transduction.

Transposable Drug Resistance Sequences

Name of the “jumping genes” that can contain drug resistant sequences that can be duplicated and transferred from plasmids to chromosomes.

Extremely

Are gene transfers frequent in nature.

Weaker dies first.

What happens if the bacterial population is exposed to the antibiotic?

Enzymes

Kind of proteins that bacteria can make that inactivate the drug.

Beta Lactam Ring

Specific structure that penicillinase break down in the penicillin.

Inhibits Beta Lactamase

What the clavulanic acid does that cause it to be added to some antibiotics

Porin

Structure that can be altered in gram-negative bacteria that reduces permeability or uptake the antibiotics.

Molecular Pumps

Structures that bacteria uses to rapidly efflux antibiotics before they can damage the cell.

Binding Site

Sites that can be altered on target molecules that will prevent antibiotics from working.

Find new pathways

How could a bacterium get around a drug like sulfonamide that prevents the synthesis of folic acid.

Viruses

75% of antibiotic prescriptions that are for upper respiratory infections, but are what these are most likely caused by.

Livestock

70% of all antibiotics in the US are given to.

Constant amplified exposure to drugs

Why would livestock antibiotics lead to antibiotic resistance.

Shipped to developing countries where controls aren’t as strict.

What has happened to excess antibiotics that are produced here in the US?

No

Do all countries require prescriptions for antibiotics?

Nanomaterials, Biological methods, Bacteriophages

New approaches to antimicrobial therapy.

Probiotics

Preparations of live microbes fed to animals or humans to improve intestinal biota.

Prebiotics

Nutrients that can be given to people to encourage the growth of beneficial microbes in the intestines.

Clostridium Difficile, Infections

Disease that might need to be treated by fecal transplants from a healthy donor.