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Microbiology > Chapter 12: Antimicrobial Agent Mechanisms of Action and Resistance > Flashcards

Chapter 12: Antimicrobial Agent Mechanisms of Action and Resistance Flashcards

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Biology 101 flashcards
1
Q

Inhibition of Bacterial Cell Wall Biosynthesis

A

Beta lactam

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2
Q

Inhibition of Folate Synthesis

A

Trimethoprim, Sulfamethoxazole

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3
Q

Interference with DNA Replication

A

Quinolones

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4
Q

Interference with DNA Transcription

A

Rifamycin

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5
Q

Interference with DNA Transcription

A

Rifamycin

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6
Q

Interference with mRNA Translation

A

Aminoglycoside

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7
Q

Antibiotics for Cell Wall Interference

A

Beta-Lactams
Penicillins
Cephalosporins
Vancomycin

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8
Q

Antibiotic for PABA -> DHFA Interference

A

Sulfonamides

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9
Q

Antibiotic for DHFA -> THFA Interference

A

Trimethoprim

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10
Q

Antibiotic for Cell Membrane Interference

A

Polymyxins

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11
Q

Antibiotics for DNA Synthesis Interference

A

Nalidixic Acid

Fluoroquinolones

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12
Q

Antibiotic for mRNA Interference

A

Rifampin

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13
Q

Antibiotic for 30S Inhibition

A

Aminoglycosides
Tetracyclines
Glycylcycline-tigecycline

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14
Q

Antibiotic for 50S Inhibition

A 
Streptogramine-DQ
Oxazolidinone-linezolid
Chloramphenicol
Clindamycin
Erythromycin
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15
Q

Steps in Peptidoglycan Biosynthesis

A
  1. Synthesis of precursors in the cytoplasm
  2. Transport of lipid-bound precursors across the cytoplasmic membrane
  3. Insertion of glycan units in the cell wall
  4. Transpeptidation linking and maturation
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16
Q

Beta – Lactam antibiotics such as penems, cephems, carbapenems, and monobactams, act by _______________

A

binding to PBP’s, which are biofunctional transpeptidase-transglycosylase enzymes that mediate peptidoglycan cross-linking

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17
Q

Glycopeptides, such as vancomycin, dalbavancin, teicoplanin, and the investigational drugs oritavancin and telavancin act by __________

A

binding to terminal D-Ala-D-Ala of the pentapeptidyl-glycosyl peptidoglycan intermediates. This prevents their incorporation into peptidoglycan chain by blocking the transpeptidation step in cell wall biosynthesis.

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18
Q

____________, the clinical spectrum of glycopeptides is limited to gram-positive microorganisms; thus they are mainly used to treat aerobic clinical infections caused by staphylococci, streptococci, and enterococci

A

Because they cannot cross the outer membrane of gram-negative bacteria

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19
Q

Antibiotics are also capable of interfering with intracellular anabolic process. The folic acid pathway provides the essential precursor molecules needed in _______

A

DNA biosynthesis

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20
Q

The pathway is mediated by two key enzymes, __________, which mediate the formation of ________ from dihydrofolate

A

dihydropteroate synthase and dihydrofolate reductase; tetrahydrofolate (THF)

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21
Q

The spectrum of activity of folate pathways inhibitors, especially when provided a combination, __________

A

provides a broad spectrum of activity against the Enterobacteriaceae that cause Urinary Tract Infection

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22
Q

Enzyme for Para-aminobenzoic Acid -> Dihydropteroate

A

Dihydropteroate Synthetase

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23
Q

Enzyme for Dihydrofolate -> Tetrahydrofolate

A

Dihydrofolate reductase

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24
Q

The enzymes necessary for DNA replication are topoisomerases ______

A

I, II, III and IV

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25
Q

Antibiotics that affect DNA replication by targeting topoisomerases II (DNA gyrase) and IV, enzymes considered important in controlling DNA replicative cycle

A

Quinolones

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26
Q

The quinolones and fluroquinolones are used to treat ___________

A

Enterobacteriaceae, pseudomonads and other non-Enterobacteriaceae, staphylococci, enterococci, Neisseria, Streptococcal species than Streptococcus pneumoniae

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27
Q

the process whereby a template DNA strand copied into functional RNA sequence, resulting in mature mRNA or structural RNA

A

DNA Transcription

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28
Q

a synthetic derivative of rifamycin B, is used in combination with other antibiotic classes to treat Mycobacterium tuberculosis

A

Rifampin

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29
Q

Aerobic species treated with rifampin include

A

staphylococci, enterococci, Haemophilus spp. and Streptococcus pneumoniae

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30
Q

Rifamycins in combination with ciprofloxacin and clindamycin are reported to be useful for the treatment of ______

A

bacterial infections relevant to biowarfare or bioterrorism, such as inhalation of anthrax.

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31
Q

the cellular machinery of living organisms that decodes mRNA into functional protein

A

mRNA translation

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32
Q

cationic carbohydrate-containing molecules, and their positive charge provides the basis for their interaction with a specific region of the 16S ribosomal subunit.

A

Aminoglycosides

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33
Q

a disaccharide aminocyclitol antibiotic produced by Streptomyces spectabilis active against many gram-negative bacterial species.

A

Spectinomycin

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34
Q

reversibly inhibit protein synthesis

A

Tetracyclines

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35
Q

Examples of Macrolides

A

erythromycin, clarithromycin, and azithromycin

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36
Q

allow initiation and mRNA translation to begin but act by inhibiting peptide elongation

A

Macrolides and Tetracyclines

37
Q

a new generation of macrolide antibiotics designed to overcome issues with bacterial resistance to macrolides. They are semi-synthetic antibiotics derived from erythromycin (macrolide antibiotic) and the changes give ketolides a broader spectrum of activity.

A

Ketolides

38
Q

The most recently approved classes of antibiotics targeting protein synthesis are the ________

A

Oxazolidinones
Streptogramins
Glycylcyclines

39
Q

Represents oxazolidinones

A

Linezolid

40
Q

Represents Streptogramins

A

quinopristin-dalfopristin

41
Q

Represents glycylcyclines

A

tigecycline

42
Q

Resistance to antibiotics is conveniently divided into mechanisms that are _____

A

instrinsic or acquired resistance.

43
Q

The gene changes or exchanges that result from acquired resistance are usually caused by ___________

A

genetic mutations, acquisition of genes from other organisms via gene transfer, or combination of mutational and gene transfer events.

44
Q

Resistance genes and transfer mechanisms existed long before the discovery and use of modern therapeutic antimicrobials. If bacterial resistance to antimicrobial agents is not a new phenomenon, where did it originate?

A

Autotoxicity; It has been postulated that the presence of DNA encoding antimicrobial resistance in antibiotic preparations has been a factor in the rapid development of multiple antibiotic resistance by providing the resistance sequences that can be incorporated by the causative pathogen

45
Q

the innate ability of bacterial species to resist the activity of a particular antimicrobial agent through inherent structural or functional characteristic, allowing tolerance of a particular drug or antimicrobial class

A

Intrinsic resistance

46
Q

Such natural resistance can be caused by the following:

A
  1. Lack of affinity of drug for bacterial target
  2. Inaccessibility of the drug into a bacterial cell
  3. Extrusion of the drug by chromosomally encoded efflux pumps.
  4. Innate production of enzymes that inactive the drug
47
Q

For antibiotics to affect internal cellular processes, they must penetrate the cell wall of bacteria to reach their target. Influx of antibiotics through the cell wall depends on the chemical nature of the antibiotics and the structural characteristics of the cell wall.

A

Impermeability

48
Q

Mechanisms of Impermeability for Gram-Negative Bacteria

A

LPS and OMPs (Outer Membrane Proteins)

49
Q

Naturally serve as outer membrane channels that permit the influx of nutrients and efflux of waste products. They also serve to restrict the influx of antibiotics and maintain low intracellular concentrations

A

Porins

50
Q

In addition, alterations leading to ________ that reduce their affinity for an antibiotic can alter a resistance phenotype.

A

decreased porin production or changes in the structure of porins

51
Q

sessile bacterial communities that are irreversibly attached to a solid surface and are embedded in an exopolysaccharide matrix

A

Biofilms

52
Q

prevalent in the clinical setting, found on numerous environmental surfaces and indwelling medical devices

A

Bacterial biofilms

53
Q

Genetic Mechanisms of Biofilm antibiotic resistance appear to fall into two general classes

A

Innate resistance factors and induced resistance factors

54
Q

Intrinsic resistance of bacteria to certain antibiotics is explained by the activity of ____

A

efflux systems and impermeability

55
Q

found in gram-positive and gram-negative bacteria and function as transporter proteins for the extrusion of toxic substances and antibiotics from the interior of the cell to the external environment

A

Efflux Pumps

56
Q

Bacterial Efflux Transporters are classified into five (5) major superfamilies

A
  1. MFS
  2. RND
  3. SMR
  4. ABC
  5. MATE
57
Q

Bacteria can provide enzymes that destroy the antimicrobial agents before they are able to reach the targets.

A

Enzymatic Inactivation

58
Q

One of the most commonly acquired and intrinsic resistance mechanism for beta lactam antibiotics.

A

Enzymatic Inactivation

59
Q

may have acquired new functions in normal housekeeping genes to help detoxify antibiotics.

A

Organisms that coevolved with antibiotic-producing organisms

60
Q

Thus, the process of natural selection, target organisms may ___________ to survive toxic environments.

A

acquire, evolve, and disseminate resistance determinants and use multiple combinations of intrinsic and acquired antibiotic resistance strategies

61
Q

Some efflux pumps have translocated to ________ which can be acquired by horizontal gene exchange.

A

Plasmids

62
Q

In general, multi-drug efflux genes are ______

A

broadly conserved in bacteria and are chromosome-encoded

63
Q

In general, multi-drug efflux genes are ______

A

broadly conserved in bacteria and are chromosome-encoded

64
Q

On the other hand, drug specific efflux genes are generally encoded _____

A

by plasmids, so their acquisition is compounded by their association with MDR

65
Q

Modification of a target can reduce the binding affinity of the antibiotic to the target; occurs primarily by chromosomal mutation, as observed with the quinolone and oxazolidinone antimicrobials, and by enzymatic alteration of macrolide, glycopeptide, and beta lactam antibiotic target sites.

A

Target site modification

66
Q

Mechanism for Target Site Modification

A

Chromosomal Mutation

Enzymatic Target Site Alteration

67
Q

Microorganisms also adapt to become resistant by acquiring cellular targets with reduced affinity for antibiotic

A

Acquisition of New Targets

68
Q

Inactivating antibiotics directly is one of the first mechanism of resistance identified in bacteria and is a successful strategy used by many organisms to survive the action of many antibiotic classes.

A

Enzymatic Inactivation of antibiotics

69
Q

Resistance is an evolutionary strategy that allows microorganisms to survive chemically hostile environments, such as those posed by antibiotic exposure. However, the evolution and vertical transfer of these resistance determinants to progeny is only part of the survival strategy used by genetic resources, including resistance genes via (LGT)

A

Dissemination

70
Q

Mechanisms of Dissemination

A 
Conjugation
Transformation
Transduction
Transposons
Insertion sequences (ISs)
71
Q

Nanotechnology to Deliver Therapeutic Agents

A 
Nanomedicine
Nanoencapsulation delivery systems
Nanoencapsulation
Encapsulating the drugs
Nanotubes
Nanoshells
Cochleates
72
Q

Class: Penems
Subclass: Penicillin
Category: Narrow Spectrum

A

US Adopted Name: Penicillin g, Penicillin v

73
Q

Class: Penems
Subclass: Penicillin
Category: Penicillinases-sensitive

A

US Adopted Name: Methicillin, Oxacillin

74
Q

Class: Penems
Subclass: Penicillin
Category: Penicillinases-resistant

A

US Adopted Name: Amoxicillin, Ampicillin

75
Q

Class: Penems
Subclass: Penicillin
Category: Broad Spectrum

A

US Adopted Name: Carbenicillin, Ticarcilin

76
Q

Class: Penems
Subclass: Penicillin
Category: Aminopenicillins

A

US Adopted Name: Piperacillin

77
Q

Class: Penems
Subclass: Penicillin
Category: Antipseudomonals

A

US Adopted Name: Amoxicillin-clavulanate

78
Q

Class: Penems
Subclass: Penicillin
Category: Extended Spectrum

A

US Adopted Name: Ampicillin-sulbactam

79
Q

Class: Penems
Subclass: Penicillin
Category: Penem-B-lactamase combinations

A

US Adopted Name: N/A

80
Q

Class: Cephems
Subclass: Cephalosporin I
Category: Narrow-spectrum, first generation

A

US Adopted Name: Cephalothin, cefazolin

81
Q

Class: Cephems
Subclass: Cephalosporin II
Category: Expanded spectrum, second generation

A

US Adopted Name: Cefocinid, Cefuroxime

82
Q

Class: Cephems
Subclass: Cephalosporin III
Category: Broad-Spectrum, Third generation

A

US Adopted Name: Cefoperazone, ceftazidime

83
Q

Class: Cephems
Subclass: Cephalosporin IV
Category: Extended Spectrum, fourth generation

A

US Adopted Name: Cefepime

84
Q

Class: Cephems
Subclass: Cephamycin
Category: N/A

A

US Adopted Name: Cefmetazole, Cefoxitin

85
Q

Class: Cephems
Subclass: Oxacephem
Category: N/A

A

US Adopted Name: Moxalactam

86
Q

Class: Cephems
Subclass: Carbacephem
Category: N/A

A

US Adopted Name: Loracarbef

87
Q

Class: Carbapenems
Subclass: N/A
Category: N/A

A

US Adopted Names: Ertapenem, Imipenem, Meropenem, and Doripenem

88
Q

Class: Monobactams
Subclass: N/A
Category: N/A

A

US Adopted Name: Aztreonam

Microbiology (2 decks)

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