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