Chapter 14

Selman Waksman

A soil microbiologist who discovered actinomycin, streptomycin, and neomycin while working with soil bacteria (actinomycetes) and fungi.

Macrobroth dilution test

Can determine the MIC and MBC by using a series of inoculated tubes treated with varying concentration of a drug. -looking for a clear tube

Which of the following has yielded compounds with the most antimicrobial activity? A. water B. air C.volcanoes ​​D. soil

D. Soil

What would AZT be effective against?

HIV

Routes of Administration

Oral, topical, or parenteral ( iv or intamuscular)

(T/F) The rate of discovery of antimicrobial drugs has decreased significantly in recent decades.

True

Howard Florey and Ernst Chain

credited with the isolation and mass production of penicillin.

Alexander Fleming

discovered penicillin

Vacomycin

isolated from actinomycetes. Bactericidal. Effective in treating infections of the gut.

Which of the following types of drug-resistant bacteria do not typically persist in individuals as a member of their intestinal microbiota? ​A. MRSA​ B. VRE​ C. CRE ​​D. ESBL-producing bacteria

A. MRSA

Which of the following routes of administration would be appropriate and convenient for home administration of an antimicrobial to treat a systemic infection? ​A. oral​ B. intravenous ​C. topical​​ D. parenteral

A. Oral

Which of the following antimicrobial drugs is synthetic?​ A.sulfanilamide ​B.penicillin​ C.actinomycin ​​D.neomycin

A. Sulfanilamide

Which of the following does not bind to the 50S ribosomal subunit?​A. tetracyclines​ B. lincosamides​ C. macrolides ​​D. chloramphenicol

A. Tetracyclines

Which of the following is an antimalarial drug that is thought to increase ROS levels in target cells?​ A. artemisinin​ B. amphotericin b ​C. praziquantel​​ D. pleconaril

A. artemisinin

In the Kirby-Bauer disk diffusion test, the _______ of the zone of inhibition is measured and used for interpretation. ​A. diameter ​B. microbial population​ C. circumference​​ D. depth

A. diameter

Which of the following resistance mechanisms is commonly effective against a wide range of antimicrobials in multiple classes?​A. efflux pump​ B. target mimicry​ C. target modification ​​D. target overproduction

A. efflux pump

The group of soil bacteria known for their ability to produce a wide variety of antimicrobials is called the ________.

Acinomycetes

Which of the following is not a type of β-lactam antimicrobial?​ A. penicillins ​B. glycopeptides​ C. cephalosporins ​​D. monobactams

B. Glycopeptides

Which of the following drug classes specifically inhibits neuronal transmission in helminths?​ A. quinolines​ B. avermectins​ C. amantadines​​ D. imidazoles

B. avermectins

Which of the following is not an appropriate target for antifungal drugs?​ A. ergosterol ​B. chitin ​C. cholesterol​​ D. β(1→3) glucan

C. Cholesterol

Which of the following resistance mechanisms describes the function of β-lactamase?​ A. efflux pump​ B. target mimicry ​C. drug inactivation​​ D. target overproduction

C. Drug inactivation

Which of the following techniques cannot be used to determine the minimum inhibitory concentration of an antimicrobial drug against a particular microbe?​ A. Etest​ B. microbroth dilution test​ C. Kirby-Bauer disk diffusion test​​ D. macrobroth dilution test

C. Kirby-Bauer disk diffusion test

Which of the following antimicrobials inhibits the activity of DNA gyrase?​ A. polymyxin B ​B. clindamycin​ C. nalidixic acid ​​D. rifampin

C. Nalidixic acid

A scientist discovers that a soil bacterium he has been studying produces an antimicrobial that kills gram-negative bacteria. She isolates and purifies the antimicrobial compound, then chemically converts a chemical side chain to a hydroxyl group. When she tests the antimicrobial properties of this new version, she finds that this antimicrobial drug can now also kill gram-positive bacteria. The new antimicrobial drug with broad-spectrum activity is considered to be which of the following? ​A.resistant​ B.semisynthetic​ C.synthetic​ D.natural

C. Synthetic

The bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.

Collostridium difficile

Which of the following terms refers to the ability of an antimicrobial drug to harm the target microbe without harming the host?​ A. mode of action​ B. therapeutic level​ C. spectrum of activity ​​D. selective toxicity

D. Selective toxicity

Which of the following is a nucleoside analog commonly used as a reverse transcriptase inhibitor in the treatment of HIV? A. acyclovir​ B. ribavirin​ C. adenine-arabinoside​​ D. azidothymidine

D. azidothymidine

Which of the following resistance mechanisms is the most nonspecific to a particular class of antimicrobials?​ A. drug modification ​B. target mimicry​ C. target modification​​ D. efflux pump

D. efflux pump

The utility of an antibiogram is that it shows antimicrobial susceptibility trends​ A. over a large geographic area.​ B. for an individual patient.​ C. in research laboratory strains.​​ D. in a localized population.

D. in a localized population

The method that can determine the MICs of multiple antimicrobial drugs against a microbial strain using a single agar plate is called the ________.

Etest

(T/F) If drug A produces a larger zone of inhibition than drug B on the Kirby-Bauer disk diffusion test, drug A should always be prescribed.

False

(T/F) Narrow-spectrum antimicrobials are commonly used for prophylaxis following surgery.

False

(T/F) β-lactamases can degrade vancomycin.

False

Benzimidazoles

Inhibit microtubule formation, reducing glucose uptake. -variety of helminth infections

Staphylococcus aureus, including MRSA strains, may commonly be carried as a normal member of the ________ microbiota in some people.

Nasal

Antiviral drugs, like Tamiflu and Relenza, that are effective against the influenza virus by preventing viral escape from host cells are called ________.

Neuraminidase inhibitors

Types of B-lactams

Penicillin B and V Cephalosporin Carbapenems Monobactems

Etest

Rather than using discs, a plastic strip is impregnated w/ different concentrations of the drug is applied to the lawn & the zone of inhibition- used to determine the MIC.

Paul Ehrlich and Sahachiro Hata

Screened more than 600 arsenic based compounds. Discovered Salvarsan (606). Effected treatment for Syphilis.

(T/F) Echinocandins, known as "penicillin for fungi," target β(1→3) glucan in fungal cell walls.

True

B-lactams

Work by preventing the crosslinking of peptide chains during the production of new peptidoglycan in the bacterial cell wall. Characterized by the presence of a B-lactam ring

What do antifungal drugs target?

a structural difference in cell membranes, targeting the lipid itself or the pathways that produce it.

Kirby-Bauer disk diffusion test

bacteria is applied to a Mueller-Hinton plate, to which disks impregnated with antibiotics. showing zones of inhibitions.

Avermectins

block neural transmission, causing paralysis and stravation - parasitic insects -river blindness -roundworms

Macrolides

boad spectrum, bacteriostatic drugs - block the elongation of proteins by inhibiting peptide bond formation b/w specific combinations of amino acids. -have a large, complex ring structure and part of a larger group of natural secondary metabolites called polyketides.

semisynthetic antimicrobials

chemically altered natural antibiotics

Joseph Klarer, Fritz Meitzch, and Gerhard Domagk

discovered Discovered the antimicrobial properties of a synthetic dye, prontosil, that could treat streptococcal and staphylococcal infections.

superinfection

infections that happen when the normal microbiota is disrupted by a antimicrobial drug, & a resistant pathogen is able to proliferate. Example: C.diff, Candidasis

Sulfonamides

inhibit folic acid synthesis

Bactericidal drugs

kill targeted bacteria

Monobactams

narrow-spectrum, gram -

Pennicillin G and V

natural antibiotic from fungi, Gram + mostly.

Cephalosporins

natural antibiotic from fungi, more resistant to B-lactase than pennicillin. Mostly Gram +

Selective toxicity antimicrobials are easier to develop against bacteria because they are ________ cells, whereas human cells are eukaryotic.

prokaryotic

Bacteriostatic drugs

reversibly inhibit bacterial growth that can start after the elimination of a drug.

Carbapenems

semi-synthetic, gram + and gram -

Rifampin

semisynthetic, blocks RNA polymerase activity. Used in a cocktail treatment for TB.

Isoniazid

specific toxicity against mycobacteria - TB

Narrow spectrum antibiotics

targets a specific subset of bacteria. Gram - or Gram + (never both)

selective toxicity

the ability of a drug to target sites that are specific to the microorganism responsible for infection.

Broad-spectrum antimicrobials

treats a wide variety of bacteria. Typically used before surgery, when narrow spectrum antibiotics fail to work, or for unknown polymicrobic infections.

Dorthy Hodgkin

used x-ray crystallography to analyze the structure of penicillin leading to the creation of semisynthetic antimicrobials -

Which of the following combinations would most likely contribute to the development of a superinfection? ​A. long-term use of narrow-spectrum antimicrobials ​B. long-term use of broad-spectrum antimicrobials ​C. short-term use of narrow-spectrum antimicrobials​​ D. short-term use of broad-spectrum antimicrobials

​C. short-term use of narrow-spectrum antimicrobials

Which clinical situation would be appropriate for treatment with a narrow-spectrum antimicrobial drug? ​A. treatment of a polymicrobic mixed infection in the intestine ​B. prophylaxis against infection after a surgical procedure ​C. treatment of strep throat caused by culture identified Streptococcus pyogenes​​ D. empiric therapy of pneumonia while waiting for culture results

​C. treatment of strep throat caused by culture identified Streptococcus pyogene