Microbiology Chapter 10 Flashcards

Questions and Answers

What are probiotics?

Are an alternative to the use of chemotherapy

Are an alternative to the use of chemotherapy involving microbial antagonism (correct)

Is a term for resistance to antibiotics

Involve the use of extracts from microorganisms

Involve microbial antagonism

Alterations in the structure of which of the following are an important aspect of Gram-negative bacterial resistance to antimicrobial drugs?

Plasmids

Cytoplasmic membrane

Porins (correct)

Mitochondria

Ribosomes

Which scientist coined the term antibiotic?

Fleming

Ehrlich

Domagk

Waksman (correct)

Kirby

Most drugs that inhibit the synthesis of the cell wall act by?

Preventing the cross-linkage of NAM subunits Signup and view all the answers

Which of the following drugs inhibits nucleic acid synthesis specifically in prokaryotes?

Quinolones Signup and view all the answers

Which of the following is NOT a criterion by which all antimicrobial agents can be evaluated?

Their activity against cell walls Signup and view all the answers

Which of the following works by inhibiting ergosterol synthesis?

Both fluconazole and turbinafine Signup and view all the answers

Which of the following statements concerning the development of antibiotic resistance is FALSE?

Resistant cells grow more efficiently and quickly than susceptible cells Signup and view all the answers

Which of the following groups of drugs can become incorporated into the bones and teeth of a fetus?

Tetracyclines Signup and view all the answers

Beta-lactamase production is an example of which of the following types of resistance?

Inactivation of the drug Signup and view all the answers

Which of the following is a measurement associated with the broth dilution test?

Lack of turbidity Signup and view all the answers

Most broad-spectrum antibiotics act by?

Inhibiting protein synthesis Signup and view all the answers

A large percentage of antibiotics and semisynthetic drugs are produced by members of the genus?

Streptomyces Signup and view all the answers

The Etest determines which of the following?

Both susceptibility and MIC Signup and view all the answers

Which of the following statements is true of selective toxicity?

Selective toxicity takes advantage of structural and/or metabolic differences between host and pathogen Signup and view all the answers

Which of the following is NOT a target of drugs that inhibit protein synthesis?

Interference with alanine-alanine bridges Signup and view all the answers

Antimicrobial sugar analogs are effective for?

Preventing virus attachment Signup and view all the answers

Antimicrobials that block protein synthesis by binding to the mRNA are?

Antisense nucleic acids Signup and view all the answers

Who discovered the first widely available antibiotic?

Domagk Signup and view all the answers

Sulfonamides are?

Were the first widely used antimetabolic antimicrobial and indirectly inhibit nucleic acid synthesis Signup and view all the answers

An antimicrobial that inhibits cell wall synthesis will result in which of the following?

Cells become more susceptible to osmotic pressure Signup and view all the answers

Which of the following statements about the zone of inhibition is FALSE?

The larger the zone, the more resistant the organism is Signup and view all the answers

Which of the following antibiotics disrupts cytoplasmic membrane function?

Amphotericin B Signup and view all the answers

Which of the following interferes with cell wall synthesis by blocking alanine bridge formation?

Both cycloserine and vancomycin Signup and view all the answers

Which of the following pathways is specifically inhibited by sulfonamides?

The conversion of PABA to dihydrofolic acid Signup and view all the answers

Infection of the ________ would be the hardest to treat with antimicrobial drugs.

brain Signup and view all the answers

It is inappropriate to prescribe antibacterial agents to treat colds or flu because?

These diseases are caused by viruses Signup and view all the answers

Which of the following is a primary advantage of semisynthetic drugs?

They have a broader spectrum of action Signup and view all the answers

The most limited group of antimicrobial agents is the ________ drugs.

Antiviral Signup and view all the answers

The cooperative activity of drugs such as beta-lactam antibiotics and clavulanic acid is known as?

Synergism Signup and view all the answers

Disruption of the normal microbiota can result in infections caused by which of the following microbes?

Candida albicans, Mycobacterium, and Clostridium difficile Signup and view all the answers

Which of the following drugs specifically targets cell walls that contain arabinogalactan-mycolic acid?

Isoniazid Signup and view all the answers

Which of the following can result when antibiotic therapy disrupts the normal microbiota?

Both pseudomembranous colitis and thrush Signup and view all the answers

Beta-lactam antibiotics have an effect on which of the following types of cells?

Bacterial cells Signup and view all the answers

The mechanism of action of the antibiotic vancomycin is?

Inhibition of cell wall synthesis Signup and view all the answers

Methicillin is an example of the beta-lactam class of drugs that?

Inhibit cell wall synthesis Signup and view all the answers

Another term for the Kirby Bauer test is?

Diffusion susceptibility test Signup and view all the answers

The tetracyclines interfere with?

Protein synthesis Signup and view all the answers

Ribavirin is an antiviral that interferes with?

Nucleic acid synthesis Signup and view all the answers

Trimethoprim is an example of antimicrobials that?

Inhibit metabolic pathways Signup and view all the answers

Which of the following antifungals works by inhibiting ergosterol synthesis?

Both fluconazole and turbinafine Signup and view all the answers

The antimicrobials called quinolones act by?

Inhibiting nucleic acid synthesis Signup and view all the answers

The antimicrobial polymyxin?

Disrupts cytoplasmic membranes Signup and view all the answers

The mechanism of action of erythromycin is?

Inhibition of protein synthesis Signup and view all the answers

Amphotericin B is an antifungal drug that?

Disrupts cytoplasmic membranes Signup and view all the answers

The mechanism of action of sulfonamides is?

Inhibition of metabolic pathways Signup and view all the answers

Because all cells engage in protein synthesis, there are few antimicrobial drugs that selectively inhibit this process.

False Signup and view all the answers

Beta-lactam drugs act by inhibiting the formation of the cytoplasmic membrane.

False Signup and view all the answers

Brain and spinal cord infections are difficult to treat because most antimicrobial drugs cannot diffuse out of the blood into these organs.

True Signup and view all the answers

Antisense nucleic acids are designed to have no side effects against humans.

True Signup and view all the answers

Some bacterial cells are resistant to a variety of antimicrobials because they actively pump the drugs out of the cell.

True Signup and view all the answers

Paul Ehrlich coined the term antibiotics for the 'magic bullet' antimicrobials he pursued.

False Signup and view all the answers

If a subculture of an MIC test grows in an MBC test, the concentration of the drug was bactericidal.

False Signup and view all the answers

The outer membrane of Gram (-) bacteria enables many antimicrobial drugs to enter the cell more easily.

False Signup and view all the answers

Organs that are commonly affected by drug toxicity include the kidneys & the liver.

True Signup and view all the answers

Many antimicrobial drugs that affect the cytoplasmic membrane are used only externally because they can be toxic to humans.

True Signup and view all the answers

Study Notes

Probiotics and Microbial Antagonism

Defined as alternatives to chemotherapy, involving microbial antagonism.
Contribute to resistance against pathogenic bacteria.

Gram-Negative Bacterial Resistance

Alterations in porins play a crucial role in antimicrobial drug resistance.

Discovery of Antibiotics

The term "antibiotic" was coined by Waksman, a significant figure in microbiology.

Cell Wall Synthesis Inhibition

Most cell wall synthesis inhibitors work by preventing the cross-linkage of NAM subunits.

Nucleic Acid Synthesis Inhibitors

Quinolones are specific drugs that inhibit nucleic acid synthesis in prokaryotes.

Evaluating Antimicrobial Agents

Activity against cell walls is NOT a universal criterion for evaluating antimicrobial agents.

Ergosterol Synthesis Inhibition

Both fluconazole and terbinafine inhibit ergosterol synthesis, crucial for fungal cell membranes.

Antibiotic Resistance Development

Resistant bacterial cells often exist as a minority and do not grow more efficiently than susceptible strains.

Tetracyclines and Fetal Effects

Tetracyclines can be incorporated into the bones and teeth of a fetus.

Drug Inactivation Resistance

Beta-lactamase production exemplifies drug inactivation resistance mechanisms.

Broth Dilution Test Measurements

Lack of turbidity indicates efficacy in the broth dilution test.

Broad-Spectrum Antibiotics

Primarily inhibit protein synthesis, affecting a wide range of microbes.

Antibiotic Production

A significant percentage of antibiotics and semisynthetic drugs originate from the genus Streptomyces.

Etest Purpose

Determines both susceptibility and minimum inhibitory concentration (MIC).

Selective Toxicity Principles

Selective toxicity exploits structural and metabolic differences between host and pathogen.

Protein Synthesis Inhibitors

Interference with alanine-alanine bridges is NOT a target for protein synthesis inhibitors.

Antimicrobial Sugar Analogs

Effective in preventing virus attachment to host cells.

Antisense Nucleic Acids

These bind to mRNA and inhibit protein synthesis.

First Widely Available Antibiotic

Domagk is credited with the discovery of the first widely available antibiotic.

Sulfonamides Overview

They were the first widely used antimetabolic antimicrobial agents, indirectly inhibiting nucleic acid synthesis.

Effects of Cell Wall Synthesis Inhibition

Leads to increased susceptibility of cells to osmotic pressure.

Zone of Inhibition Misconceptions

A larger zone does not indicate greater resistance; it signifies more susceptibility.

Cytoplasmic Membrane Disruptors

Amphotericin B is an antibiotic that disrupts the cytoplasmic membrane function.

Drugs Blocking Alanine Bridge Formation

Cycloserine and vancomycin inhibit cell wall synthesis specifically through this mechanism.

Sulfonamides Action Pathway

They specifically inhibit the conversion from PABA to dihydrofolic acid.

Challenging Infections to Treat

Brain infections are particularly difficult due to poor drug diffusion from blood to tissue.

Inappropriate Antibacterial Use

Antibacterial agents are ineffective against colds or flu as these illnesses are viral in origin.

Advantages of Semisynthetic Drugs

They offer a broader spectrum of action compared to their natural counterparts.

Limited Antimicrobial Agent Groups

Antiviral drugs represent the most limited category within antimicrobial agents.

Synergism in Drug Interaction

Cooperative activity between beta-lactam antibiotics and clavulanic acid exemplifies synergism.

Disruption of Normal Microbiota

Can lead to infections from opportunistic microbes like Candida albicans and Clostridium difficile.

Specific Targets of Isoniazid

Specifically targets cell walls containing arabinogalactan-mycolic acid.

Consequences of Antibiotic Disruption

Includes conditions like pseudomembranous colitis and thrush due to loss of normal microbiota.

Beta-Lactam Antibiotics Target

Primarily affect bacterial cells by inhibiting cell wall synthesis.

Vancomycin's Mechanism of Action

Functions by inhibiting cell wall synthesis, crucial for bacterial integrity.

Methicillin's Function

A beta-lactam drug that inhibits bacterial cell wall synthesis.

Alternate Name for Kirby-Bauer Test

Known as the diffusion susceptibility test, assessing antibiotic effectiveness.

Tetracycline Functionality

Interfere with protein synthesis, crucial for bacterial growth.

Ribavirin's Impact

Inhibits nucleic acid synthesis, utilized as an antiviral medication.

Trimethoprim's Activity

Acts by inhibiting metabolic pathways critical in bacterial nucleic acid synthesis.

Quinolones Mechanism

Specifically inhibit nucleic acid synthesis, making them effective antimicrobials.

Antibiotic Polymyxin

Known to disrupt cytoplasmic membrane integrity, leading to cell death.

Erythromycin's Action

Inhibits protein synthesis, targeting ribosomal functions in bacteria.

Amphotericin B Characteristics

An antifungal that disrupts the cytoplasmic membrane, utilized against fungal infections.

Sulfonamides Mechanism Overview

Primarily inhibit metabolic pathways linked to bacterial growth.

Antimicrobial Drug Selectivity

There are few drugs that selectively inhibit protein synthesis due to its essential role in all cells.

Misconceptions about Beta-Lactam Drugs

They do not act by disrupting cytoplasmic membranes but target cell wall synthesis.

Brain Infections Treatment Difficulty

Antimicrobial drugs face challenges reaching the brain due to blood-brain barrier limitations.

Antisense Nucleic Acids Safety

Designed to minimize side effects to human cells while targeting viral mRNA.

Bacterial Resistance Mechanisms

Some bacteria actively efflux drugs through pumps, contributing to multi-drug resistance.

Misattribution of Antibiotic Terminology

Paul Ehrlich did not coin the term antibiotics; it was popularized later.

Interpretation of MIC and MBC Tests

If a subculture of an MIC test grows in an MBC test, it indicates the drug was bacteriostatic, not bactericidal.

Gram-negative Outer Membrane

The outer membrane acts as a barrier to many antimicrobial agents, hindering their entry.

Organ Toxicity and Drug Side Effects

Organs like kidneys and liver are often affected by the toxicities of various antimicrobial drugs.

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Test your understanding of key concepts in microbiology with these flashcards from Chapter 10. Each card features important terms and definitions that are crucial for mastering the subject. Perfect for review or quick reference before exams.