Lecture 3 Flashcards
What are 3 physical antimicrobial techniques used?
heat, radiation, and filtration
What are 3 chemical antimicrobial techniques used?
disinfectants, antisceptics, and antimicrobials
What are antibiotics?
a chemical substance produced by a bacterium that kills/inhibits the growth of another bacterium
What are antisceptics?
kills microbial cells but not eukaryotic cells
Which type of antimicrobial technique can damage eurkaryotic cells?
disinfectants
What does bacteriostatic mean?
inhibits growth of bacteria
What does bacteriocidal mean?
kills bacterium
What does bacteriolytic mean?
lyses bacterium
Who and when was penicillin discovered?
Alexander fleming, 1928
What year was penicillin started to be used medically?
1945
Who developed the concept of toxicity?
Paul Erlich
What was the cause in the increase of life expectancy between 1830 and 1900?
the Golden Age of Microbiology
What is sulfanilamide?
analog of PAD (component of folic acid)
How does sulfanilamide work at a molecular level?
inhibits fold acid synthesis (competitive inhibition) in bacteria
How do eukaryotic cells and bacterial cells get folic acid?
bacteria needs to make them because can’t uptake it, eukaryotic uptakes it from environment
What is the most common group of antibiotics?
cephalosporin and penicillin
What antibiotic group do cephalosporin and penicillin belong to?
beta-lactam antibiotics
What are the 3 things that limit the efficacy of antimicrobial drugs?
speed of action, sensitivity of target, side effects
In terms of speed of action, why do some antibiotics have a weaker or faster effect than other antibiotics?
availibility of target, location of target, and mode of taking the antibiotic or the body organ comes into play || pills take a longer time to take effect
What are broad-spectrum of antibiotics?
act on broad-spectrum type of targets bacterial species; ie: targets any bacteria with a glycine interbridge (= includes all gram+ species)
What are narrow-spectrum of antibiotics?
antibiotic that targets only one type of species
If you are a doctor prescribing a patient antibiotics without having much time to come up with a diagnostic, which type of antibiotic will you prescribe: broad or narrow?
broad = don’t know what specifically is going on
How are antibiotics selective?
only target prokaryotic cell and not eukaryotic cells
Which type of antibiotic is best used for an infection? Bacteriocidal or bacteriostatic and why?
depends on the situation but it is safer to use bacteriostatic for those pathogens that have endotoxins (if lysed = endotoxins are released)
What is an example of antibiotic selectivity that reduces the pathogen’s toxicity to the host?
inhibiting metabolic that are only present in microbes
What are 3 methods bacteria become resistant to antibiotics?
synthesis of an enzyme that breaks down antibitoic || prevent antibiotic from accessing target site || modification of the target site
3 ways how bacteria can become resistant to antibiotics?
over-usage of an antibiotic or non-compliance; over-usage in agriculture; over prescription (use of antibiotics when no need to)
How can non-compliance with a antibiotic medication lead to antibiotic resistance?
may not kill ALL pathogens inside = will create mutations against antibiotic and pass on that resistance gene via plasmids to other bacterium or new progeny
What are the 3 main types of super-bugs?
Clostridium difficile, Neisseria gonnhorae, CP-resistent enterobacteriaceae
What is clostridium difficile?
opportunistic pathogen found in healthy microbiota but with over-usage of antibiotics = kill other microbes = C.diff will take over and make you sick
What are the 4 types of antibiotics?
B-lactam antibiotics, vancomycin, quinolones, antiribosomal antibiotics
What are beta-lactam antibiotics?
consists of a beta-lactam ring structure where the variation happens at the n-acyl group
What type of affect will beta-lactam antibiotics on a bacterial species? (bacteriostatic, bacteriolytic, or bacteriocidal)
bacteriocidal
Which type of target sensitivity do beta-lactam antibiotics have?
broad-spectrum
What is Penicillin G?
first antibiotic by FLeming, works better on Gram+ than on Gram–
What are 3 examples of beta-lactam antibiotics?
penicillin, cephalosporins, cephamycins
Why doesn’t penicillin work well with gram– bacteria?
outer-membrane doesn’t allow antibiotic to penetrate through it
What type of penicillin-alternative is used for gram– bacteria?
ampicillin
What is autolysin?
gene/protein that degrades peptidoglycan cell wall
How can a penicillin be bacteriostatic?
If the bacteria doesn’t have the gene for autolysin = cell wall synthesis will only be affected
Why is penicillin considered a bacteriocidal antibiotic?
inhibits penicillin-binding proteind (peptidases) new synthesis of cell wall and (if autolysin is present) begins to degrade current cell wall –> leads to bacterial cells to lyse
What are beta-lactamases?
enzymes produced by pathogens that reduce permeability across outer-membrane = alters penicillin-binding proteins || breaks down b-lactam antibiotics
What is vancomycin?
glycopeptide antibiotic
What type of affect will vancomycin antibiotics on a bacterial species? (bacteriostatic, bacteriolytic, or bacteriocidal) How?
bacteriostatic = blocks synthesis of cell wall
Why can’t you tale vancomycin orally?
protein-based = cannot take as a pill
What does vancomyin target? In what type of bacteria and how?
D-alanine peptide blocks incorportation of another sugar chain onto growing polypeptide; only in gram+
What is vancomycin used to treat?
MRSA infections
How can we use protein-based antibiotics?
as a cream
How does bacteria build up resistance to vancomycin?
alters peptide sequence in peptidoglycan so vancomycin doesn’t bind to it
What are quinolones?
inhibit the action of bacterial DNA gyrase topoisomerase = breakdown of bacterial DNA
What are topoisomerases?
makes DNA more compact
What happens when you inhibit topoisomerase action?
cause DNA to breakdown
What type of effect will quinolone antibiotics on a bacterial species? (bacteriostatic, bacteriolytic, or bacteriocidal) How?
bacteriolytic
What are 2 ways bacteria can become resistant to quionolones?
change in topoisomerase or DNA gyrase or bacterium can develop a mechanism by removing antibiotic from the cytoplasm via efflux pump and pump it out into environment
Which type of target sensitivity do anti-ribosomal antibiotics have?
broad-spectrum
What are 3 examples of anti-ribosomal antibiotics?
tetracycline, erythromycin, streptomycin
What do anti-ribosomal antibiotics bind to?
30S or 50S ribosomal subunit
What are 3 methods bacterial species can be resistant to anti-ribosomal antibiotics?
reducing cell envelope permeability, modifying target, excretion of antibiotic from bacterial cytoplasm
