Which of the following microbial systems are most commonly exploited to control the growth of microorganisms?
Microbial nutrition
| Term | Definition |
|---|---|
Which of the following microbial systems are most commonly exploited to control the growth of microorganisms? | Microbial nutrition |
What are biocides? | Antimicrobials that can be used to control microbes. |
What makes up a good chemical disinfectants? | -Hydrophilic
-Effective against multiple various infectious agents.
-Not toxic to people/animals
-Has viricidal properties |
What biocide is effective over a range of 4-80 Celsius? | Vaporized hydrogen peroxide (VPH). |
Which US Government body dictates over antiseptics guidelines? | FDA (Food and Drug Administration). |
What are 2 effective ways of preventing/stopping growth of microorganisms? | -Starvation
-Poisoning |
Is higher or lower ethanol count more effective at killing bacteria? | Lower ethanol percentage in water is more effective.
The more alcohol present will cause proteins to denature and aggregate together. This will actually form a more protective coat around the bacteria. BAD! |
What chemical control agents work best against bacterial endospores? | -Formaldehyde
-Ethylene oxide |
Which US government body dictates on disinfectants' effectiveness? | EPA (Environmental Protection Agency). |
Who discovered that bacteriophage could be helpful against dysentery? | Felix d'Herelle |
Which biocide is effective over a pH range of 4-10. | Chlorine dioxide (ClO2) |
Which biocide is known for its sporicidal activity and instability of an active solution? | Glutaraldehyde |
Which biocide is known for being rapidly microbicidal and corrosive? | Iodine |
Which pathogens can bacteriophage lyse? | -Listeria
-Salmonella
-E. coli |
What are forms of biological control against microbes? | -Bacterial predation
-Virus infection |
What are bacteriocins? | Microbial toxins that can be used to control unwanted microbial populations. |
When were bacteriophages first used to treat humans? | Early 1900s |
What term includes both natural and chemically synthesized compounds? | Antimicrobial agent |
A successful antimicrobial agent has what property? | Selective toxicity. |
What is the therapeutic index? | The ratio of the toxic dose to the therapeutic dose. |
What is a good therapeutic index number/ratio? | A higher therapeutic index is better as it means a dose that can harm a person is way higher than the dose needed to desist the infection. |
What is the therapeutic dose? | The drug level require to treat a specific infection. |
What is the toxic dose? | The drug level required to harm the host. |
What do bacterial depolymerases do? | Hydrolyze biofilm matrixes and microbial toxins like bacteriocins. |
What is selective toxicity? | The ability to kill/inhibit a pathogen while not harming the host. |
Why does penicillin have a high therapeutic index? | Penicillin has peptidoglycan as its cellular target.
Host/Humans cells do not have peptidoglycan as it's a feature of bacteria cells only.
So, eukaryotes cannot be harmed from penicillin, causing a high therapeutic index. |
What has made major contributions to antimicrobials in current use? | -Soil bacteria
-Fungi
-Synthetic compounds
-Chemical modifications of antibiotics |
What is the term for naturally occurring antibiotics modified with additional chemical groups? | Semi-synthetic antibiotics. |
What are narrow-spectrum drugs? | Drugs only effective to a limited number of pathogens. |
What are typical sources of antimicrobial agents? | -Soil bacteria
-Fungus
-Synthetic agents
-Semisynthetic agents |
What are broad-spectrum drugs? | Drugs that are effective against multiple pathogens. |
What does penicillin have selective toxicity for? | Peptidoglycan |
What does bactericidal mean? | Kills bacteria |
What does bacteriostatic mean? | Inhibits bacterial growth |
Vancomycin is what kind of spectrum drug? | Narrow |
What is vancomycin effective against? | Gram-positive bacteria |
Which host system eliminates pathogens targeted by static antimicrobial agents? | Immune system |
What is the minimal inhibitory concentration (MIC)? | The concentration of drug necessary to prevent bacterial/pathogen growth. |
What is the Etest? | An antibiotic susceptibility test that uses small strips containing an antibiotic gradient to determine MIC. |
Sulfonamides are what kind of spectrum drugs? | Broad. |
On Etest strips, what does the intersection between the inhibition zone and the MIC scale indicate? | The concentration of antibiotic required to inhibit bacterial growth |
The most selective antibiotics in common use target what? | Bacterial cell walls synthesis |
What are the tests of the Etest? | 1. Inoculate surface of agar plate with bacteria
2. Place Etest strips on the plate surface
3. Incubate plates for 24-48 hours
4. Determine MIC = find point of intersectionality. |
Which component of penicillin's structure is most important for its antimicrobial activity? | Beta-lactam ring |
How does pencillin target peptidoglycan? | It blocks the enzymes trying to form cross-links with peptidoglycan in the cell wall. |
What does penicillin do? | -Inhibit transpeptidase rxn in cell wall synthesis
-Activates bacterial autolytic enzymes |
How does penicillin kill pathogen cells? | Osmotic lysis |
What are examples of narrow spectrum antibiotics? | -Penicillin G
-Penicillin V
-Methicillin |
Why are semisynthetic penicillins harder for beta-lactamase enzymes to degrade? | They have bulkier side chains compared to natural penicillin. |
Which semisynthetic penicillins are known to be difficult for beta-lactamase enzymes to degrade? | -Nafcillin
-Oxacillin
-Methicillin |
What are beta-lactamases enzymes? | Enzymes bacteria produce to resist penicillin |
What is another name for beta-lactamase? | Penicillinases |
What are examples of broad spectrum antibiotics? | -Amoxicillin
-Ampicillin |
What are the chemical functional groups of the beta-lactam ring? | A ketone, an ether, and a nitrogen |
What can beta-lactamases destroy? | Synthetic penicillin and certain semisynthetic penicillin. |
What are the 2 new classes of beta-lactam drugs? | -Carbapenems
-Monobactams |
What is vaborbactam? | A beta-lactamase inhibitor. |
How does vaborbactum inhibit beta-lactamase enzymes? | It will bind noncompetitively to the beta-lactamase active site. |
What is vancomycin? | A glycopeptide antibiotic produce by Amycolatopsis orientalis. |
What does vancomycin do? | It will block transpeptidase activity by binding to the enzyme's substrate instead of the enzyme itself. |
What is the most critical component in vancomycin's structure? | Pentapeptide portion. |
What antiobiotic inhibits transpeptidation reaction of cell wall synthesis but does NOT have a beta-lactam ring? | Vancomycin |
What type of spectrum does vancomycin affect. | Narrow |
What is important for patients to know about carbapenems and monobactams? | These drugs can not be taken orally. |
Which antibiotic is considered to be a last resort? | Vancomycin |
What is vancomycin considered to be a last resort drug for? | Staphylococcus aureus |
What does combination therapy do for beta-lactam antibiotic treatment? | It prevents bacteria to produce beta-lactamase enzyme that can destroy the beta-lactam antibiotics. |
What do aminoglycosides target? | 30S ribosomal DNA |
What do macrolides target? | 50S ribosomal subunits |
What do oxazolidinones target? | 70S initiation complex synthesis. |
What do all aminoglycosides have structurally? | A cyclohexane ring and amino sugars. |
Aminoglycosides and macrolides disrupt _____. | Protein synthesis. |
Why do aminoglycosides have toxic effects on human cells? | Human mitochondrial ribosomes share binding sites with bacterial ribosomes. |
What are tetracylines? | Antibiotics with 4 ring structure with a variety of different side chains. |
What do tetracyclines target? | The protein synthesis of 30S subunits. |
What kind of drugs are tetracyclines? | Semisynthetic |
What are potential side effects of using aminoglycosides? | Oto toxicity (affects hearing)
Renal toxicity (affects kidneys) |
Aminoglycosides cause ____ of peptide synthesis. | Early termination |
What are macrolides known for structurally? | A lactone ring linked to 1+ sugars. |
What is an example of macrolide antibiotics? | Erythromycin |
What are examples of bacteriostatic antibiotics? | -Macrolides
-Tetracyclines
-Aminoglycosides |
What are ketolides? | Semisynthetic derivatives of macrolides. |
What is a negative cost of using lincosamides? | Can support an overgrowth of C. difficile, a pathogen that causes a diarrheal infection. |
What can lincosamides be effective against? | -anaerobic bacteria
-Gram-positive cocci |
What are oxazolidinones? | Synthetic drugs made up of a heterocyclic five membered ring structure. |
What do oxazolidinones target? | Protein synthesis of 23S rRNA within 50S subunits.
They also prevent the assembly of the 70S initiation complex. |
What are the benefits of ketolides? | -Better acid stability
-Better Oral bioavailability |
What is an antimetabolite? | A substance that blocks the function of a specific biochemical pathway? |
What are antimetabolites similar in structure to? | The substrate of key enzymes |
What kind of antibacterial drugs are antimetabolites considered to be? | Broad spectrum and bacteriostatic |
What are sulfonamides? | Structural analogues of PABA; their structure is similar to p-aminobenzoic acid. |
What do sulfonamides target? | Synthesis of folic acid |
Folic acid is the precursor of what? | Purines |
Why do sulfonamides have a high therapeutic index? | Bcuz sulfonamides target biochemical pathways that humans do not use |
What is the relationship between antimetabolites and natural substrates? | They compete with one another to bind at the active site. |
What are trimethoprims? | Synthetic antibiotics that target the synthesis of folic acid by binding to dihydrofolate reductase. |
What is a synergistic effect? | A term to describe the dynamic drugs have when interactions between them enhance each other's effects. |
Which antibiotic can be use to help treat UTIs? | Trimethoprim |
What do antibacterial drugs that inhibit nucleic acid target? | DNA polymerase and Topoisomerase |
What do fluoroquinolones target to disrupt DNA replication? | -Topoisomerase 4
-DNA gyrase |
What is the least selectively toxic kind of antibiotic drugs? | Ones that inhibit nucleic acid synthesis |
What are fluoroquinolones? | Antibacterial drugs that block nucleic acid synthesis |
What do rifamycin class antibiotics inhibit? | Cell growth |
What do rifamycin class antibiotics bind to? | RNA polymerase |
What is rifampin useful against? | Mycobacterial infections. |
Why do HIV infected individuals require life long drug therapy? | The virus remains dormant in immune cells. |
What is the significance of lenacapavir in the fight against HIV? | It drastically reduced the risk of HIV infection with minimal dosing. |
What do sofosbuvir, ledipasvir and velpatasvir all target? | -Viral RNA polymerase
-Viral replication enzyme |
How often do patients of HIV take lenacapavir doses? | 2x per year |
Why are there less antifungal drugs vs antibacterial? | Fungal cells are closer to human cells so its harder to make drugs with high selectively. |
What do sofosbuvir, ledipasvir and velpatasvir drugs all used to cure? | Hepatitis C virus |
What are azoles? | Antifungal drugs that block ergosterol synthesis. |
What is Pneumocystis jirovecii? | An organism that can cause a life threatening systemic mycosis. |
What do antiprotozoan drugs known to target? | Metabolic processes and nucleic acid synthesis |
What do antifungal agents target? | Inhibit sterol synthesis and disrupt fungal membrane permeability |
What does VRE stand for? | Vancomycin-resistant enterococci |
What is approximate # of antimicrobial resistant infections reported in the US? | 3 million |
What is acquired resistance? | Antibiotic resistance that happens when a genome in bacterium changes from a sensitive cell to a resistant cell. |
What does CRE stand for? | Carbapenem resistant Enterobacteriaceae |
What antimicrobial resistant bacterial has raised concern due to its resistance to pan-drugs? | Candida auris |
What are drug tolerant bacteria? | Ones that do not respond to antibiotics bcuz they are embedded in the biofilm matrix or they grow too slowly. |
What is intrinsic resistance? | Resistance caused by a particular structural feature of the bacterial cell |
What does MRSA stand for? | Methicillin resistant Staphylococcus aureus |
What do efflux pumps do? | Run antiport channels for protons to enter the cell as the drug leaves |
What is horizontal gene transfer? | Drug resistance when bacteria gain new properties by acquiring genes from bacteria |
What resistance happens to antibiotics due to inactivation of a drug? | -Activity of beta-lactamase
-Addition of acetyl-CoA to chloramphenicol |
What has a significant contribution to the maintenance of drug resistant genes in a bacterial population? | Exposing bacteria to the drug |