Test
MICRO LAB Quiz Chapter 12
Este test tiene tipos de pregunta que se abren en el reproductor de siempre.
Preguntas del test (42)
1Chemical compounds to kill or suppress microorganisms
[blank_start]Antimicrobial agents[blank_end]- AAntimicrobial agents
2Natural, semisynthetic, or synthetic molecules used to treat or prevent disease
[blank_start]Antibiotics[blank_end]- AAntibiotics
3Key steps for antimicrobial agent to inhibit/kill microorganism:
Must be in active form
[blank_start]Pharmacodynamics[blank_end]- APharmacodynamics
4• Key steps for antimicrobial agent to inhibit/kill microorganism:
Must be able to achieve sufficient levels or concen-trations at site of infection
[blank_start]Pharmacokinetics[blank_end]- APharmacokinetics
5• Inhibit bacterial growth but do not kill the organism
[blank_start]Bacteriostatic agents[blank_end]- ABacteriostatic agents
6Mode of Action of Antibacterial Agents
• Inhibitors of cell wall synthesis
1. [blank_start]Beta-lactams[blank_end]
2. [blank_start]Glycopeptides[blank_end]- ABeta-lactams
- BGlycopeptides
7Mode of Action of Antibacterial Agents
• Inhibitors of Folic Acid Synthesis
1. [blank_start]Sulfonamides[blank_end]
2. [blank_start]Trimethoprim[blank_end]- ASulfonamides
- BTrimethoprim
8Mode of Action of Antibacterial Agents
• Inhibitors of DNA & RNA synthesis
1. [blank_start]Fluoroquinolone[blank_end]
2. [blank_start]Ciprofloxacin[blank_end]
3. [blank_start]Metronidazole[blank_end]
4. [blank_start]Rifampin[blank_end]- AFluoroquinolone
- BCiprofloxacin
- CMetronidazole
- DRifampin
9Inhibitors of Protein Synthesis
• Binds to 30S
[blank_start]Aminoglycosides[blank_end]
[blank_start]Tetracyclines[blank_end]
[blank_start]Glycylcyclines[blank_end]- AAminoglycosides
- BTetracyclines
- CGlycylcyclines
10Inhibitors of Protein Synthesis
• Binds to 50S
[blank_start]Macrolide-Lincosamide-Streptogramin[blank_end]
[blank_start]Oxazolidinone[blank_end]
[blank_start]Chloramphenicol[blank_end]- AMacrolide-Lincosamide-Streptogramin
- BOxazolidinone
- CChloramphenicol
11Mode of Action of Antibacterial Agents
• Inhibitors of Cell Membrane functions
[blank_start]Lipopeptides[blank_end]
[blank_start]Polymixins[blank_end]- ALipopeptides
- BPolymixins
12Murein other name: [blank_start]Peptidoglycan[blank_end]
- APeptidoglycan
13• Peptidoglycan/murein production
1. Synthesis of precursors in the cytoplasm
2. Transport of lipid-bound precursors across the cytoplasmic membrane
3. Insertion of glycan units into the cell wall
4. Transpeptidation linking and maturation
• [blank_start]D-cycloserine[blank_end] and [blank_start]bacitracin[blank_end] inhibit steps 1 and 2
• [blank_start]Beta-lactams[blank_end] and [blank_start]glycopeptides[blank_end] inhibit steps 3 and 4- AD-cycloserine
- Bbacitracin
- CBeta-lactams
- Dglycopeptides
14Beta-lactam
•Binds [blank_start]enzymes[blank_end] involved in [blank_start]peptidoglycan[blank_end] production
•[blank_start]Penicillin-binding proteins[blank_end] (PBPs)
•[blank_start]Transpeptidase-transglycosylase[blank_end] enzymes
•Mediate [blank_start]peptidoglycan cross-linking[blank_end]
•Natural and semisynthetic- Aenzymes
- Bpeptidoglycan
- CPenicillin-binding proteins
- DTranspeptidase-transglycosylase
- Epeptidoglycan cross-linking
15[blank_start]Beta-lactam ring[blank_end]
• Similar to [blank_start]acyl-D-alanyl-D-alanine[blank_end]
• Normal substrate for synthesis of linear glycopeptide in the bacteri-al cell wall
• Must pass through cell wall [blank_start]porins[blank_end] in gram-negative cells to reach cell PBPs
• Binding of the type of B-lactam to specific PBPs
• Influences effectiveness of certain drugs on specific organisms
• For Gram-positive and Gram-negative- Aacyl-D-alanyl-D-alanine
- Bporins
- CBeta-lactam ring
16[blank_start]Glycopeptides[blank_end]
• Binds to the terminal D-Ala-D-Ala of the [blank_start]pentapeptidyl-glycosyl peptidoglycan[blank_end] intermediates
• Bind to the [blank_start]substrate[blank_end] of the transpeptidation enzyme
• Blocks the [blank_start]transpeptidation step[blank_end] in cell wall biosynthesis
• [blank_start]Vancomycin[blank_end], [blank_start]dalbavancin teicoplanin[blank_end], [blank_start]oritavancin[blank_end] and [blank_start]telavancin[blank_end]
• Mainly for Gram-positive- AGlycopeptides
- Bpentapeptidyl-glycosyl peptidoglycan
- Csubstrate
- Dtranspeptidation step
- EVancomycin
- Fdalbavancin teicoplanin
- Goritavancin
- Htelavancin
17Inhibition of Folate Synthesis
Folic acid pathway
•Provides precursor molecules needed in DNA syn-thesis
•Combined antibiotic: SXT
(SXT = [blank_start]Sulfamethoxazole[blank_end] + [blank_start]Trimethoprim[blank_end])
•For [blank_start]enterobacter[blank_end]-caused UTI
Sulfonamides
•Binds [blank_start]dihydropteroate synthase[blank_end]
•[blank_start]Sulfamethoxazole[blank_end] (SMZ)
[blank_start]Trimethoprim[blank_end] (TMP)
•Binds [blank_start]dihydrofolate reductase[blank_end]- ASulfamethoxazole
- BTrimethoprim
- Centerobacter
- DSulfamethoxazole
- ETrimethoprim
- Fdihydropteroate synthase
- Gdihydrofolate reductase
18Interference with DNA Replication
• Enzymes involved in DNA replication
• Topoisomerase [blank_start]1[blank_end], [blank_start]2[blank_end], [blank_start]3[blank_end] and [blank_start]4[blank_end] (numbers)- A4
- B3
- C2
- D1
19Interference with DNA Replication
Quinolones/[blank_start]Fluoroquinolones[blank_end]
• Gram([blank_start]+[blank_end]): Targets topoisomerase II ([blank_start]DNA gyrase[blank_end])
• Gram([blank_start]-[blank_end]): Targets topoisomerase IV
• New generations can target both enzymes- A+
- B-
- CFluoroquinolones
- DDNA gyrase
20Interference with DNA Transcription
• Rifampin
• Synthetic derivative of [blank_start]rifamycin B[blank_end]
• Targets [blank_start]RNA polymerase B[blank_end] subunit at an allosteric site
• Also blocks RNA chain elongation- ARNA polymerase B
- Brifamycin B
21Interference of mRNA Translation
• Inhibits protein synthesis
• Binds to 30S or 50S ribosomal subunits
[blank_start]30S[blank_end] ribosomal subunit:
• aminoglycosides, spectinomycin, tetracyclines, glycylcyclines
[blank_start]50S[blank_end] ribosomal subunit:
• macrolides, lincosamides, streptogramins, chloramphenicol,
oxazolidinones, ketolides- A30S
- B50S
22Interference of mRNA Translation
[blank_start]Aminoglycosides[blank_end]
• Results in mistranslation and subsequent production of
aberrant proteins
• Promotes cell leakage and enhance penetration
of other antibiotics- AAminoglycosides
23Interference of mRNA Translation
[blank_start]Spectinomycin[blank_end]
• Interferes with the stability of peptidyl tRNA binding to the
ribosome
• Does not cause mistranslation- ASpectinomycin
24Interference of mRNA Translation
[blank_start]Tetracycline[blank_end]
• Tetracylcin, doxycycline, and minocycline
• Results in the premature release of tRNA and termination
of peptide bond formation
Toxicity
• Upper gastrointestinal effects
• Cutaneous phototoxicity
• Photoallergic immune reaction- ATetracycline
25Interference of mRNA Translation
[blank_start]Macrolides[blank_end]
• erythromycin, clarithromycin, and azithromycin
• allow initiation and mRNA translation to being but act by
inhibiting peptide elongation- AMacrolides
26Interference of mRNA Translation
[blank_start]Ketolides[blank_end]
• [blank_start]Telithromycin[blank_end]
• Bypass macrolide-resistant mechanisms by improving ribosome
binding affinity- AKetolides
- BTelithromycin
27Interference of mRNA Translation
[blank_start]Oxazolidinones[blank_end]
• [blank_start]Linezolid[blank_end]
• For Gram (+): MRSA, VRE, S. pneumoniae, M. tuberculosis
• Blocks the initiation step and translocation of peptidyltRNA
MRSA = [blank_start]Methicillin[blank_end]-[blank_start]resistant[blank_end] [blank_start]Staphylococcus[blank_end] [blank_start]aureus[blank_end]
VRE = [blank_start]Vancomycin[blank_end]-[blank_start]Resistant[blank_end] [blank_start]Enterococci[blank_end]- AOxazolidinones
- BLinezolid
- CMethicillin
- Dresistant
- EStaphylococcus
- Faureus
- GVancomycin
- HResistant
- IEnterococci
28Interference of mRNA Translation
[blank_start]Streptogramin[blank_end]
• [blank_start]70[blank_end]:[blank_start]30[blank_end] mixture of A and B molecules called [blank_start]Dalfopristinquinupristin[blank_end]
• Disrupt translation by blocking elongation and binding of
aminoacyl-tRNA- ADalfopristinquinupristin
- BStreptogramin
- C70
- D30
29Interference of mRNA Translation
[blank_start]Glycylcycline[blank_end]
• [blank_start]Tigecycline[blank_end]
• Higher affinity for [blank_start]30S[blank_end] ribosomal subunit than tetracycline
• Increased effectiveness against tetracycline-resistant organisms
• Wide spectrum of activity agains gram-positive, gramnegative
and atypical pathogens- A30S
- BTigecycline
- CGlycylcycline
30Mechanisms of Antibiotic Resistance
Some resistance is 2000 years old
• [blank_start]Canadian glaciers[blank_end]
Some resistance in deep sea areas is 10,000 years old
• [blank_start]Near Papua New Guinea[blank_end]
Evolution of resistance
• May have occurred as a way to prevent autotoxicity- ACanadian glaciers
- BNear Papua New Guinea
31Mechanisms of Antibiotic Resistance
Resistance
[blank_start]Intrinsic[blank_end] resistance
• Naturally found in bacteria (chromosomal)
[blank_start]Acquired[blank_end] resistance
• Acquired from exogenous DNA (plasmid or through [blank_start]conjugation[blank_end])- AIntrinsic
- BAcquired
- Cconjugation
32Intrinsic Antibiotic Resistance
1. [blank_start]Impermeability[blank_end]
2. [blank_start]Biofilms[blank_end]
3. [blank_start]Efflux[blank_end]
4. [blank_start]Enzyme Inactivation[blank_end]- AImpermeability
- BBiofilms
- CEfflux
- DEnzyme Inactivation
33Intrinsic Antibiotic Resistance
[blank_start]Impermeability[blank_end]
• Influx through cell wall depends on:
• Chemical nature of drug
• Structural characteristics of cell wall
Examples:
Intrinsic resistance to vancomycin
• Gram(-): impermeable to VA
• [blank_start]Lactobacillus[blank_end] and [blank_start]Leuconostoc[blank_end]: lack precursor
target for VA to bind in cell wall
Intrinsic resistance to penicillin
• [blank_start]Enterococcus faecalis[blank_end] and [blank_start]Enterococcus faecium[blank_end]: their
PBPs have low affinity to penicillins- AImpermeability
- BLactobacillus
- CLeuconostoc
- DEnterococcus faecalis
- EEnterococcus faecium
34Intrinsic Antibiotic Resistance
[blank_start]Biofilms[blank_end]
• Sessile bacterial communities that are irreversibly attached to a
solid surface and are embedded in an exopolysaccharide matrix
• Highly resistant to antibiotic exposure
Resistance mechanisms
• Multifactorial; cell-cell chemical communication which
varies from organism to organism
• Not attributed to typically acquired genetic mechanisms
• Determined by chemical and physical characteristics of
biofilm formation- ABiofilms
35Intrinsic Antibiotic Resistance
Efflux
• Efflux pumps
• Transporter proteins for the extrusion of toxic substances
and antibiotics
• Increase secretion of drug
Classified into Superfamilies:
• [blank_start]Major facilitator[blank_end] (MFS)
• [blank_start]Resistance nodulation cell division[blank_end] (RND)
• [blank_start]Small multidrug resistance family[blank_end] (SMR)
• [blank_start]Adenosine triphosphate[blank_end] (ATP)-[blank_start]binding cassette[blank_end] (ABC)
• [blank_start]Multidrug and toxic effects[blank_end] (MATE)- AMajor facilitator
- BResistance nodulation cell division
- CSmall multidrug resistance family
- DAdenosine triphosphate
- Ebinding cassette
- FMultidrug and toxic effects
36Intrinsic Antibiotic Resistance
Enzyme Inactivation
• Production of enzymes that destroy the drug
• Most common: [blank_start]beta-lactamase[blank_end]
Hydrolyze B-lactam antibiotics by:
• Metallo-based mechanism of action
• Serine-based mechanism of action
B-lactamase inhibitors: [blank_start]clavulanic acid[blank_end], [blank_start]sulbactam[blank_end], and
[blank_start]tazobactam[blank_end]- Abeta-lactamase
- Bclavulanic acid
- Csulbactam
- Dtazobactam
37Acquired Antibiotic Resistance:
1. [blank_start]Efflux[blank_end]
2. [blank_start]Target Site Modification[blank_end]
3. [blank_start]Acquisition of New Targets[blank_end]
4. [blank_start]Enzymatic Inactivation of Antibiotics[blank_end]- AEfflux
- BTarget Site Modification
- CAcquisition of New Targets
- DEnzymatic Inactivation of Antibiotics
38Acquired Antibiotic Resistance
[blank_start]Efflux[blank_end]
• Increases the secretion of drug
• Multidrug efflux genes are broadly conserved in bacteria and are
chromosome-encoded
• Drug-specific efflux genes are generally encoded by [blank_start]plasmids[blank_end]
• ~~Confer resistance to different antimicrobials in several organisms- AEfflux
- Bplasmids
39Acquired Antibiotic Resistance:
[blank_start]Target Site Modification[blank_end]
• Can reduce the binding affinity to the antibiotic to the target
Mechanisms:
[blank_start]Chromosomal Mutation[blank_end]
• Observed with quinolone and oxazolidinone
• Caused by mutations encoding amino acid changes in
the genes encoding enzymes used for DNA or RNA synthesis
[blank_start]Enzymatic Target Site Alteration[blank_end]
• Observed in macrolide, glycopeptide, and B-lactam
• Enzymes alter antibiotic targets resulting in reduced affinity
and effectiveness- ATarget Site Modification
- BChromosomal Mutation
- CEnzymatic Target Site Alteration
40Acquired Antibiotic Resistance:
[blank_start]Acquisition of New Targets[blank_end]
• Microorganisms acquire new cellular targets with reduced affinity to
antibiotic
[blank_start]Target site substitution[blank_end]
• Acquisition of a new enzyme that is unaffected by drugs
or creates a new pathway
Observed in MRSA
• [blank_start]Staphylococcus aureus[blank_end] evaded methicillin by acquiring a mobile element
carrying a [blank_start]staphylococcal[blank_end] [blank_start]cassette[blank_end] [blank_start]chromosome[blank_end] [blank_start]mec[blank_end] (SCCmec)
mecA gene encodes [blank_start]PBP2A[blank_end] and [blank_start]PBP2A’[blank_end]
• Reduced affinity for beta-lactams
• Responsible for methicillin resistance- APBP2A
- BPBP2A’
- CAcquisition of New Targets
- DTarget site substitution
- EStaphylococcus aureus
- Fstaphylococcal
- Gcassette
- Hchromosome
- Imec
41Acquired Antibiotic Resistance:
[blank_start]Enzymatic Inactivation of Antibiotics[blank_end]
Enzymes produced by the microorganisms inactivate antibiotics directly
• Destroy antibiotic
• Modification rendering it ineffective- AEnzymatic Inactivation of Antibiotics
42Dissemination
[blank_start]Lateral gene transfer[blank_end] (LGT)
•Two processes: [blank_start]Physical movement[blank_end], [blank_start]Incorporation into genome[blank_end]
Mechanisms of transfer
• [blank_start]Plasmids[blank_end]
• [blank_start]Transposons[blank_end] (Tn)
• [blank_start]Integrons[blank_end]
• [blank_start]Insertion sequences[blank_end]
[blank_start]Plasmids[blank_end]
• Transformation or conjugation
[blank_start]Transposons[blank_end] (Tn)
• Mobile genetic elements
• Contain transposase for nonhomologous
recombination
• Insertion sequences
• ~~~Example NR1 in [blank_start]Shigella flexneri[blank_end]
[blank_start]Integrons[blank_end]
• Genetic elements that capture mobile gene
cassettes by site-specific recombination
• ~~[blank_start]Site-specific recombinase[blank_end] (intl)
• ~~[blank_start]Primary recombination site[blank_end] (attl)
• [blank_start]Insertion sequences[blank_end]
• ~~Short DNA sequences that act as simple transposable elements- APhysical movement
- BIncorporation into genome
- CLateral gene transfer
- DPlasmids
- ETransposons
- FIntegrons
- GInsertion sequences
- HPlasmids
- ITransposons
- JShigella flexneri
- KIntegrons
- LSite-specific recombinase
- MPrimary recombination site
- NInsertion sequences
Información
- Descripción
- Microbiology Test sobre MICRO LAB Quiz Chapter 12, creado por Adri Torres el 05/11/2016.
- Autor
- Adri Torres
- Idioma
- English
- Visitas
- 3
- Etiquetas
- Valoración
- Aún sin valoraciones Valora este test