Di - Micro + Immuno Exam I: Antimicrobials

Front 1

Appropriate use of an antibiotic that reduces the chances that resistance will occur include
(A) Prescribing Erythromycin for infections caused by viruses
(B) Prescribing Vancomycin for infections caused by Gram negative bacteria
(C) Prescribing Tetracycline for an infection caused by a bacterial species expressing an extended-spectrum beta-lactamase (ESBL).
(D) Prescribing Ampicillin for an infection caused by a bacterial species expressing an extended-spectrum beta-lactamase (ESBL).

Back 1

(C) Prescribing Tetracycline for an infection caused by a bacterial species expressing an extended-spectrum beta-lactamase (ESBL).

Front 2

A serious infection by an anaerobic Gram negative bacterial species is best treated with _________.
A. Metronidazole
B. Bacitracin
C. Isoniazid
D. Vancomycin
E. Rifampin

Back 2

A. Metronidazole

Front 3

Erythromycin is
(A) Protein synthesis inhibitor
(B) An inhibitor of Nucleic acid synthesis
(C) An inhibitor of Cell wall synthesis
(D) A peptide antibiotic that disrupts membranes
(E) An antimetobolite

Back 3

(A) Protein synthesis inhibitor

Front 4

An infection caused by a bacterial species expressing an extended-spectrum β-lactamase (ESBL) should be treated with _________.
A. penicillin
B. ampicillin
C. tetracycline
D. cephalosporin
E. amoxicillin

Back 4

C. tetracycline

Front 5

Which of the following statements is true?
(A) Tetracyclines bind reversibly to the 60S ribosomal subunit
(B) Tetracyclines bind reversibly to the 30S ribosomal subunit
(C) Aminoglycosides bind reversibly to the 30S ribosomal subunit
(D) Aminoglycosides and tetracyclines are bacteriostatic
(E) Aminoglycosides bind irreversibility to the 50S ribosomal subunit

Back 5

(B) Tetracyclines bind reversibly to the 30S ribosomal subunit

Front 6

tetracycline and carbapenems are examples of _____ spectrum antibiotics

Back 6

Broad

Front 7

Metronidazole is effective against strict anaerobes and some protozoa, while
penicillin is effective only against Gram positive bacteria. Therefore they can be classified as _____ _____ antibiotics

Back 7

Narrow Spectrum

Front 8

What are the Types of Antibacterial Agents?

Back 8

Inhibition of Cell Wall Synthesis

Disruption of Membranes

Inhibition of Nucleic Acid Synthesis

Inhibition of Protein Synthesis

Antimetabolites

Front 9

Fosfomycin and Cycloserine inhibit phase 1 of...

Back 9

cell wall synthesis

Front 10

Vancomycin and Bacitracin are active at the cell membrane and...

Back 10

Inhibit cell wall synthesis in phase 2

Front 11

Beta-Lactams (penicillin, etc) inhibit phase 3 of cell wall synthesis by what mechanism?

Back 11

Inhibition of polymerization of new peptidoglycan

Front 12

Bacitracin inhibits phase 2 of cell wall synthesis by what mechanism?

Back 12

combines with carrier molecules at the membrane

Front 13

Vancomycin inhibits phase 2 of cell wall synthesis by what mechanism?

Back 13

combines with cell wall substrates and prevents peptidoglycan from cross-linking.

Front 14

Vancomycin is not effective against Gram-negative bacteria, but it is useful to treat...

Back 14

Gram-positive infections caused by organisms that are resistant to b-lactams

Front 15

Beta-Lactam Antibiotics include:

Back 15

Penicillins
Cephalosporins and Cephamycins
Monobactams and Carbapenems

Front 16

The enzymes involved in this final process of cell wall formation are called ?

Back 16

penicillin-binding proteins

Front 17

ß-lactam antibiotics contain a four-membered ring, which undergoes an _________ reaction with the transpeptidases that cross-link the peptidoglycan polymers

Back 17

acylation

Front 18

Clavulanic acid binds irreversibly to bacterial enzymes that degrade ________.

Back 18

penicillin

Front 19

Cephalosporins are b-lactam antibiotics where the b-lactam ring is fused with a ________ _______

Back 19

dihydrothiazine ring.

Front 20

Monobactams are narrow spectrum because they are only effective against...

Back 20

aerobic Gram negative bacteria

Front 21

What are Three general mechanisms for resistance to Beta-lactam antibiotics?

Back 21

1. Prevention of the interaction between the PBP and the antibiotic (changes in porins)

2. Modification of the interaction between the PBP and the antibiotic (Overproduction or modified PBP)

3. Hydrolysis of the antibiotic by Beta-lactamases (More than 200 different b-lactamases have been described)

Front 22

What is Isoniazid?

Back 22

Isoniazid is bactericidal against actively replicating Mycobacteria

Isoniazid inhibits synthesis of mycolic acid

Resistance to isoniazid results both from decreased uptake of the drug into the cells and by alteration of the enzymes involved in mycolic acid synthesis

Front 23

What are polymyxin B and colistin?

Back 23

high-molecular-weight octapeptides that inhibit Gram-negative bacteria

Not active against Gram positive bacteria – no outer membrane

Interact with the membrane and cause increased cell permeability

Only used topically - bind to various ligands in body tissues and are potent toxins for the kidney and nervous system

Front 24

These synthetic agents inhibit gyrase (bacterial topoII) or topoisomerase IV thereby interfering with DNA replication, recombination and repair

Back 24

Quinolones

Nalidixic acid: was used against Gram negative bacteria

Ciproflaxacin: Gm+ and Gm-

Front 25

Nitroimidazoles are DNA damaging agents that inhibit anaerobic bacteria and protozoa. Mammalian cells and aerobic bacteria (including facultative bacteria) are unharmed because...

Back 25

they lack enzymes to reduce the nitro group of these agents.

Front 26

Metroniadazole is one of the most commonly used...

Back 26

nitroimidazols

Front 27

Rifamycins (Rifampin, Rifabutin) bind to bacterial ____ ________ and inhibit initiation of RNA synthesis

Back 27

RNA polymerase

Front 28

Rifampin is bactericidal for M. tuberculosis and active against many...

Back 28

Gram positive bacteria

Front 29

Gram negative bacteria are intrinsically resistant to rifamycins because of...

Back 29

decreased uptake of the drug

Front 30

Kanamycin, tobramycin and gentamicin are...

Back 30

Aminoglycosides

Front 31

Aminoglycosides Irreversibly bind to the ____ ribosomal subunit.

Back 31

30S

Front 32

Aminoglycosides are Effective against many Gram-negative and some Gram-positive bacteria but not useful for...

Back 32

anaerobic (oxygen required for uptake of antibiotic) or intracellular bacteria

Front 33

Beta-lactams increase the uptake of the _______, acting synergistically with them

Back 33

aminoglycosides

Front 34

Resistance to Aminogylcosides can result from what>

Back 34

Mutation of the ribosomal binding site


Decreased uptake of the antibiotic

Increased expulsion of the antibiotic (efflux)

Enzymatic modification of the antibiotic: Most common form of resistance. Phosphotransferases
Adenyltransferases
Acetyltransferases

Front 35

Tetracycline, Doxycycline, Minocycline bind to the 30S subunit and block binding of ______

Back 35

aminoacyl-tRNA

Front 36

Tetracyclines are ____ spectrum

Back 36

Broad Spectrum

Used to treat a wide variety of infections caused by:
Chlamydia
Mycoplasma
Rickettsia
And a variety of other Gram positive and Gram negative bacteria

Front 37

What is the mechanism of action of Oxazolidinones (Linezolid)?

Back 37

Bind the 50S ribosomal subunit and distorts the binding site for the tRNA and inhibits formation of the 70S initiation complex

Front 38

Oxazolidinones are Narrow spectrum, active against Gram positive cocci and have a unique mechanism of action so cross resistance with other protein inhibitors does not occur. They are most commonly used against what?

Back 38

drug resistant enterococci

Front 39

What is the mechanism of action for Lincomycin and its derivative Clindamycin?

Back 39

Block protein elongation by binding to the 50S subunit of the ribosome

Front 40

Lincomycin and its derivative Clindamycin are effective against what?

Back 40

Staphylococci and anaerobic Gram-negative rods

Not active against most aerobic Gram negative bacteria

Front 41

Not commonly used in the US because it can disrupt protein synthesis in human bone marrow and cause aplastic anemia (1 in 60,000 patients)

Back 41

Chloramphenicol

Front 42

Chloramphenicol Binds reversibly to the ____ ribosomal subunit

Back 42

50S

Front 43

Macrolides Binds reversibly to the ___ RNA component of the 50S ribosomal subunit

Back 43

23S

Front 44

Erythromycin, Azithromycin and Clarithromycin are...

Back 44

Macrolides

Front 45

Macrolides are broad spectrum, but are primarily used to treat...

Back 45

pulmonary infections

Mycoplasma, Legionella and Chlamydia species

Front 46

Cyclic peptides administered as a combination of two components

Back 46

Streptogramins


The Group A component binds to the 50S ribosomal subunit and facilitates binding of the Group B component, which inhibits chain elongation

Front 47

The most commonly used Steptogramin

Back 47

quinupristin-dalfopristin

Front 48

Streptogramins are Most commonly used against

Back 48

staphylococci, streptococci and Enterococcus faecium. - primarily against vancomycin resistant E. faecium

Front 49

Sulfonamides are Antimetabolites that inhibit...

Back 49

pteroic acid synthetase

Front 50

Trimethoprims are Antimetabolites that inhibit...

Back 50

dihydrofolate reductase