Antimicrobials: Agents, Resistance and Design Flashcards
Define
Acquired resistance
occurs when a particular microorganism obtains the ability to resist the activity of an antimicrobial agent to which it was previously susceptible
Define
ADMET
Initialism of absorption, distribution, metabolism, excretion, toxicity: A set of test categories used together in drug discovery to provide insight into how a pharmaceutical drug interacts with the body as a whole
Define
Aminoglycosides
any of a group of antibiotics (as streptomycin and neomycin) that inhibit bacterial protein synthesis and are active especially against gram-negative bacteria
Define
Antimicrobial agents
A general term for drugs, chemicals, or other substances that either kill or slow the growth of microbes
Define
Bactericidal
an agent that kills bacteria
Define
Bacteriostatic
an agent that prevents the growth of bacteria
Define
β-lactamases
enzymes produced by bacteria that provide multi-resistance to β-lactam antibiotics such as penicillins, cephalosporins, cephamycins, and carbapenems (ertapenem),
Define
β-lactams
a class of antibiotic consisting of all antibiotic agents that contain a beta-lactam ring in their molecular structures. This includes penicillin derivatives (penams), cephalosporins (cephems), monobactams, carbapenems and carbacephems
Define
Cephalosporins
a large group of antibiotics derived from the mold Acremonium. They are bactericidal (kill bacteria) and work in a similar way to penicillins
Define
Colistin
an antibiotic produced by certain strains of the bacteria Paenibacillus polymyxa. It is effective against most Gram-negative bacilli
Define
Fidaxomicin
an oral macrolide antibiotic labeled for the treatment of Clostridium difficile–associated diarrhea in adults
Define
Fluoroquinolones
any of a group of fluorinated derivatives (such as ciprofloxacin and levofloxacin) of quinolone that are used as antibacterial drugs
Define
Forward pharmacology
the traditional approach to discovering new drugs. Typically, a library of chemical compounds is screened for causing a desired phenotype in cells / tissue
Define
High-throughput screening
recent scientific methods relevant to the field of chemistry and biology, in which hundreds of thousands of experimental samples are subjected to simultaneous testing under given conditions
Define
Hit to lead
a stage in early drug discovery where small molecule hits from a high throughput screen (HTS) are evaluated and undergo limited optimization to identify promising lead compounds
Define
Horizontal Gene Transfer (HGT)
the movement of genetic material between unicellular and/or multicellular organisms other than by the (“vertical”) transmission of DNA from parent to offspring (reproduction)
Define
In silico screening
Producing and screening drug candidates on a computer or via computer simulation
Define
Intrinsic resistance
a natural insensitivity in bacteria that have never been susceptible to a particular antibiotic
Define
Klebsiella pneumoniae carbapenemase (KPC)
a group of emerging highly drug-resistant Gram-negative bacilli causing infections associated with significant morbidity and mortality
Define
Lead optimisation
the process by which a drug candidate is designed after an initial lead compound is identified
Define
Macrolides
a class of antibiotic that includes erythromycin, roxithromycin, azithromycin and clarithromycin. They are useful in treating respiratory, skin, soft tissue, sexually transmitted, H. pylori and atypical mycobacterial infections
Define
Mobilised colistin resistance (MCR)
a gene confers plasmid-mediated resistance to colistin, one of a number of last-resort antibiotics for treating Gram-negative infections
Define
New Dehli metallo-β-lactamase
an enzyme that makes bacteria resistant to a broad range of beta-lactam antibiotics. These include the antibiotics of the carbapenem family, which are a mainstay for the treatment of antibiotic-resistant bacterial infections
Define
Nosocomial infections
infections that have been caught in a hospital and are potentially caused by organisms that are resistant to antibiotics
Define
Omp protein
a protein involved in signal transduction. It is a highly expressed, cytoplasmic protein found in mature olfactory sensory receptor neurons of all vertebrates
Define
Oxazolidinones
a novel class of synthetic antimicrobial agents unrelated to any other antibacterial drug class. They were originally developed as monoamine oxidase inhibitors for treatment of depression, with subsequent recognition of their antimicrobial properties
Define
Penicillin
an antibiotic or group of antibiotics produced naturally by certain blue molds, and now usually prepared synthetically
Define
Pharmacodynamics
what the drug does to the body
Define
Pharmacokinetics
what the body does to the drug
Define
Porin protein
beta barrel proteins that cross a cellular membrane and act as a pore, through which molecules can diffuse
Define
Quinolones
a member of a large group of broad-spectrum bacteriocidals that share a bicyclic core structure related to the compound 4-quinolone
Define
Resistome
a proposed expression by Gerard D. Wright for the collection of all the antibiotic resistance genes and their precursors in both pathogenic and non-pathogenic bacteria
Define
Reverse pharmacology
the science of integrating documented clinical/experiential hits, into leads by transdisciplinary exploratory studies and further developing these into drug candidates by experimental and clinical research
Define
Rifamycins
a natural antibiotic produced by Streptomyces mediterranei, it is a commonly used antimycobacterial drug that inhibits prokaryotic DNA-dependent RNA synthesis and protein synthesis; it blocks RNA-polymerase transcription initiation
Define
Selective toxicity
refers to the ability of the drug to targets sites that are relative specific to the microorganism responsible for infection
Define
Sulphonamides
a group of man-made (synthetic) medicines that contain the sulfonamide chemical group. They may also be called sulfa drugs
Define
Tetracyclines
a class of antibiotics that may be used to treat infections caused by susceptible microorganisms such as gram positive and gram negative bacteria, chlamydiae, mycoplasmata, protozoans, or rickettsiae
Define
Thienamycin
one of the most potent naturally produced antibiotics known thus far, was discovered in Streptomyces cattleya in 1976. It has excellent activity against both Gram-positive and Gram-negative bacteria and is resistant to bacterial β-lactamase enzymes
Define
Transglycosylation
A mechanism for glycosidic (see GLYCOSIDE) bond formation, particularly during polysaccharide synthesis. Nucleoside phosphate derivatives act as activated donor compounds in which the energies of their glycosidic bonds are partially conserved in the reaction products
Define
Transpeptidation
a chemical reaction (as the reversible conversion of one peptide to another by a protease) in which an amino acid residue or a peptide residue is transferred from one amino compound to another
Define
Trimethoprim
an antibiotic used mainly in the treatment of bladder infections. Other uses include for middle ear infections and travelers’ diarrhea
Define
Vancomycin
an antibiotic that when taken by mouth fights bacteria in the intestines. It is used to treat an infection of the intestines caused by Clostridium difficile, which can cause watery or bloody diarrhea
Definition
occurs when a particular microorganism obtains the ability to resist the activity of an antimicrobial agent to which it was previously susceptible
Acquired resistance
Definition
Initialism of absorption, distribution, metabolism, excretion, toxicity: A set of test categories used together in drug discovery to provide insight into how a pharmaceutical drug interacts with the body as a whole
ADMET
Definition
any of a group of antibiotics (as streptomycin and neomycin) that inhibit bacterial protein synthesis and are active especially against gram-negative bacteria
Aminoglycosides
Definition
A general term for drugs, chemicals, or other substances that either kill or slow the growth of microbes
Antimicrobial agents
Definition
an agent that kills bacteria
Bactericidal
Definition
an agent that prevents the growth of bacteria
Bacteriostatic
Definition
enzymes produced by bacteria that provide multi-resistance to β-lactam antibiotics such as penicillins, cephalosporins, cephamycins, and carbapenems (ertapenem),
β-lactamases
Definition
a class of antibiotic consisting of all antibiotic agents that contain a beta-lactam ring in their molecular structures. This includes penicillin derivatives (penams), cephalosporins (cephems), monobactams, carbapenems and carbacephems
β-lactams
Definition
a large group of antibiotics derived from the mold Acremonium. They are bactericidal (kill bacteria) and work in a similar way to penicillins
Cephalosporins
Definition
an antibiotic produced by certain strains of the bacteria Paenibacillus polymyxa. It is effective against most Gram-negative bacilli
Colistin
Definition
an oral macrolide antibiotic labeled for the treatment of Clostridium difficile–associated diarrhea in adults
Fidaxomicin
Definition
any of a group of fluorinated derivatives (such as ciprofloxacin and levofloxacin) of quinolone that are used as antibacterial drugs
Fluoroquinolones
Definition
the traditional approach to discovering new drugs. Typically, a library of chemical compounds is screened for causing a desired phenotype in cells / tissue
Forward pharmacology
Definition
recent scientific methods relevant to the field of chemistry and biology, in which hundreds of thousands of experimental samples are subjected to simultaneous testing under given conditions
High-throughput screening
Definition
a stage in early drug discovery where small molecule hits from a high throughput screen (HTS) are evaluated and undergo limited optimization to identify promising lead compounds
Hit to lead
Definition
the movement of genetic material between unicellular and/or multicellular organisms other than by the (“vertical”) transmission of DNA from parent to offspring (reproduction)
Horizontal Gene Transfer (HGT)
Definition
Producing and screening drug candidates on a computer or via computer simulation
In silico screening
Definition
a natural insensitivity in bacteria that have never been susceptible to a particular antibiotic
Intrinsic resistance
Definition
a group of emerging highly drug-resistant Gram-negative bacilli causing infections associated with significant morbidity and mortality
Klebsiella pneumoniae carbapenemase (KPC)
Definition
the process by which a drug candidate is designed after an initial lead compound is identified
Lead optimisation
Definition
a class of antibiotic that includes erythromycin, roxithromycin, azithromycin and clarithromycin. They are useful in treating respiratory, skin, soft tissue, sexually transmitted, H. pylori and atypical mycobacterial infections
Macrolides
Definition
a gene confers plasmid-mediated resistance to colistin, one of a number of last-resort antibiotics for treating Gram-negative infections
Mobilised colistin resistance (MCR)
Definition
an enzyme that makes bacteria resistant to a broad range of beta-lactam antibiotics. These include the antibiotics of the carbapenem family, which are a mainstay for the treatment of antibiotic-resistant bacterial infections
New Dehli metallo-β-lactamase
Definition
infections that have been caught in a hospital and are potentially caused by organisms that are resistant to antibiotics
Nosocomial infections
Definition
a protein involved in signal transduction. It is a highly expressed, cytoplasmic protein found in mature olfactory sensory receptor neurons of all vertebrates
Omp protein
Definition
a novel class of synthetic antimicrobial agents unrelated to any other antibacterial drug class. They were originally developed as monoamine oxidase inhibitors for treatment of depression, with subsequent recognition of their antimicrobial properties
Oxazolidinones
Definition
an antibiotic or group of antibiotics produced naturally by certain blue molds, and now usually prepared synthetically
Penicillin
Definition
what the drug does to the body
Pharmacodynamics
Definition
what the body does to the drug
Pharmacokinetics
Definition
beta barrel proteins that cross a cellular membrane and act as a pore, through which molecules can diffuse
Porin protein
Definition
a member of a large group of broad-spectrum bacteriocidals that share a bicyclic core structure related to the compound 4-quinolone
Quinolones
Definition
a proposed expression by Gerard D. Wright for the collection of all the antibiotic resistance genes and their precursors in both pathogenic and non-pathogenic bacteria
Resistome
Definition
the science of integrating documented clinical/experiential hits, into leads by transdisciplinary exploratory studies and further developing these into drug candidates by experimental and clinical research
Reverse pharmacology
Definition
a natural antibiotic produced by Streptomyces mediterranei, it is a commonly used antimycobacterial drug that inhibits prokaryotic DNA-dependent RNA synthesis and protein synthesis; it blocks RNA-polymerase transcription initiation
Rifamycins
Definition
refers to the ability of the drug to targets sites that are relative specific to the microorganism responsible for infection
Selective toxicity
Definition
a group of man-made (synthetic) medicines that contain the sulfonamide chemical group. They may also be called sulfa drugs
Sulphonamides
Definition
a class of antibiotics that may be used to treat infections caused by susceptible microorganisms such as gram positive and gram negative bacteria, chlamydiae, mycoplasmata, protozoans, or rickettsiae
Tetracyclines
Definition
one of the most potent naturally produced antibiotics known thus far, was discovered in Streptomyces cattleya in 1976. It has excellent activity against both Gram-positive and Gram-negative bacteria and is resistant to bacterial β-lactamase enzymes
Thienamycin
Definition
A mechanism for glycosidic (see GLYCOSIDE) bond formation, particularly during polysaccharide synthesis. Nucleoside phosphate derivatives act as activated donor compounds in which the energies of their glycosidic bonds are partially conserved in the reaction products
Transglycosylation
Definition
a chemical reaction (as the reversible conversion of one peptide to another by a protease) in which an amino acid residue or a peptide residue is transferred from one amino compound to another
Transpeptidation
Definition
an antibiotic used mainly in the treatment of bladder infections. Other uses include for middle ear infections and travelers’ diarrhea
Trimethoprim
Definition
an antibiotic that when taken by mouth fights bacteria in the intestines. It is used to treat an infection of the intestines caused by Clostridium difficile, which can cause watery or bloody diarrhea
Vancomycin
What are some examples of natural antimicrobial agents?
Penicillin
Aminoglycosides
Polyenes
What are some examples of semisynthetic antimicrobial agents?
β-lactams
Cephalosporins
What are some examples of synthetic antimicrobial agents?
Oxazolidinones
Quinolones
What is the mode of action of antibiotics?
Disruption of cell membrane funciton
Inhibition of cell wall synthesis
Inhibition of RNA and DNA synthesis
Inhibition of folic acid metabolism
Inhibition of protein sythesis
What is the basic monomer of peptidoglycan
A peptapeptide with D-ala D-ala at the end of the stem
What do Penicillin-Binding proteins (PBPs) do?
PBPs play multiple roles in cell wall synthesis and maintenance of peptidoglycan:
- transglycosylation (wall synthesis for growth and septation)
- transpeptidation (crosslinking and remodelling)
- peptide cleavage (D-Ala carboxypeptidases, endopeptidases)
- control of crosslinking, insertion of new strands
What is a critical part in the action of PBPs? What happens when you interupt it?
A critical part of these processes is the recognition of the D-Ala-D-Ala sequence of the MurNac-GlcNac pentapeptide. Interfering with this recognition disrupts the cell wall synthesis
How do β-lactams act as antibiotics (general idea)?
The β-lactam ring mimics the structure of the D-Ala-D-Ala link and bind to the same place in the PBPs (the active site), disrupting the crosslinking process.
β-lactams inactivate PBPs.
β-lactams are bacteriocidal/bacteriostatic
β-lactams are bacteriocidal
How does resistance to β-lactams occur?
Resistance occurs through production of β-lactamases or PBP and porin mutations
How do glycopeptide antibiotics, like Vancomycin, work?
Bind to the terminal D-Ala-D-Ala dipeptide inhibiting transglycosylation and transpeptidation of peptidoglycan.
Which antibiotics interfere with cell wall biosynthesis?
β-lactams
Vancomycin
What antibiotics inhibit protein synthesis?
Tetracyclines
Aminoglycosides
Macrolides
Oxazolidinones
Why can molecules that target bacterial ribosomes be used as antibiotics?
Selective toxicity due to differences in bacterial/eukaryotic ribosomes
What are examples of antibiotics that target the 30S subunit?
Aminoglycosides
Tetracyclines
What are examples of antibiotics that target the 50S subunit?
Macrolides
Oxazolidinones
How do tetracyclines function?
Bind to the 30S ribosomal subunit preventing entry of amino acyl-tRNA into the A-site
How does resistance to tetracyclines occur?
Resistance through efflux or ribosomal protection proteins
How do aminoglycosides funtion?
Interfere with proof-reading process for incoming aa-tRNA • Results in premature termination or proteins with amino acid substitutions
How does resistance to aminoglycosides occur?
Resistance through target mutations and modifying enzymes
How do macrolides function?
Bind reversibly to 23S rRNA in 50S subunit (peptidyl transferase domain)
Disrupt movement of tRNA from A site to P site thereby inhibiting peptide chain elongation.
How does resistance to macrolides occur?
Multiple resistance mechanisms
- Target modification (e.g., RNA methylation)
- Efflux
- Enzymatic modification
How do Oxazolidinones function?
Bind to rRNA on the A side of the peptidyltransferase center (PTC) of the ribosome
How does resistance to Oxazolidinones occur?
Resistance mediated through rRNA mutations
Which antibiotics act as inibitors of nucleic acid synthesis?
Fluoroquinolones
Rifamycins
Fidaxomicin
How do Fluoroquinolones function?
Bind to DNA gyrase and topoisomerases blocking formation of complex with nicked DNA
Blockage of DNA replication and DNA repair