Bacterial Pathogenesis Final Part 3 Flashcards
What is the definition of an antiviral?
Chemotherapeutic agents able to inhibit the replication cycle of viruses
What is the difference between antibiotics and anti microbial?
Antibiotics kill/inhibit the growth of just bacteria and anti microbials can kill fungi, viruses, Protozoa as well
What is the difference between broad-spectrum and narrow-spectrum antibiotics?
Broad are effective on both gram neg and pos, narrow are only effective on one or the other
Which type of bacteria are antibiotics less effective in treating?
Gram negative, because of the peptidoglycan and cytoplasm
What are the 6 modes of interference that antibiotics use?
- Inhibition of cell wall synthesis
- Inhibition of protein synthesis
- Inhibition of transcription
- Inhibition of nucleic acid replication
- Inhibition of synthesis of essential metabolites
- Injury to the membrane
What do beta lactams do?
Interrupt peptidoglycan synthesis by binding to the X-linking enzyme
What kind of ribosomes do prokaryotes and eukaryotes have?
Pro: 70S (50+30), Euk: 80S (60+40)
How does Chloramphenicol work?
Binds to the 50S subunit and stops the peptide bond from forming
How does Tetracycline work?
Stops attachment of tRNA to mRNA ribosome complex
How does erythromycin work?
Stops translocation of ribosome along mRNA
How does streptomycin work?
Changes the shape of the 30S portion, causes the code on mRNA to read incorrectly
Why do antibiotics not damage human cells?
- humans don’t have peptidoglycan
- eukaryotic and prokaryotic cells have different RNA POL, ribosome and DNA gyrases
- humans don’t synthesize folic acid
What are two examples of opportunistic pathogens that can establish after taking antibiotics?
Candida, C. Diff
What is the minimal inhibitory concentration?
The lowest concentration before bacterial growth is observed in the test tube
What are the 4 ways bacteria can resist antibiotics?
- Alters the target site
- Antibiotic exclusion
- Inactivation
- Efflux
How does antibiotic exclusion work?
- gram negative bacteria are intrinsically resistant
- antibiotic is too large to pass through porin
How does antibiotic inactivation work?
- bacteria make antibiotic inactivating enzymes (ex. Beta-lactamase inactivates penicillin)
How does antibiotic efflux work?
Bacteria have membrane proteins that transport antibiotics out of the cell by active transport
How does target site alteration work?
- alter the target site so the antibiotic can’t bind
- ex. Erythromycin resistant bacteria alter the 50S ribosome
What are the three kinds of horizontal gene transfer?
- Transformation
- Transduction
- Conjugation
How does transformation HGT work?
- uptake of DNA fragments from the environment from dead cell
- one of the strands are degraded
- com gene must be expressed
How does a bacteria change after transformation happen?
Genotype is changed because nucleotides were added, phenotype may also change
How does transduction work?
- bacteriophage (virus that infects bacteria)
- phage injects genetic material into cell and uses host cell to make copies of genome and destroys the host cell genome
- sometimes phage gets a piece of bacterial DNA and carries it to a different bacteria
How does conjugation work?
- plasmids transfer between bacteria via the retractible pilus
What is phage therapy?
The use of viruses to attack bacteria to treat pathogenic bacterial infections
Why is phage therapy more effective for mucosal surfaces and not systemic infections?
The immune system will mount a response to the phages before they can do anything
