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Lecture

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Department
Biology
Course
BIOL 2900
Professor
Malini Persaud
Semester
Fall

Description
Mechanisms of antibiotic resistance - degradation, expelling drugs, modification, altered target site (for penicillin, still has energy for the enzymatic energy to stop the pencilin binding protein) Antimicrobial drug resistance mechanisms inactivation of antibiotics - enzymes that alter the antibiotic to inactivate its function. For ex. Modification: chloramphenical acetyl transferase For ex. Degradation: beta-lactacame Resistance by degradation - produce beta lactamase (penicillinase), this destroys antibiotic by breaking the breakage of the beta lactam ring. Pencilin can bind to beta lactamase and to pencilin binding protein. Clavulinic Acid - binds strongly to beta lactamases which inhibits their activity (good inhibitor) - Synergistic effect with pencilin and cephalosporin’s Altered target side - the bacterial cell can alter or eliminate the target side for the antibiotics. For example, penicillin binding proteins (transpeptidase) Antimicrobial drug resistance mechanism: antibiotic-efflux pump - antibiotic efflux pumps is a common pump that expels antibacterial drugs (eg.tetracyclines) from bacterial cells. (this pumps out antibiotics before it can even do its job) - vancomycin, year developed 1956 ND RESISTANCE OBSERVED IN 1988 WHILE METHICILIN WAS DEPLOYED IN 1960 AND ESISTANCE OBSERVED IN 1961. (* know how antibiotic resistance was developed?) Multiple Resistance - Pathogen can acquire resistance to more than one drug at a time - commn when R-plasmids exchanged - Developed in hospitals and nursing homes; constant use of drugs eliminates sensitive cells. - Multiple drug resistance (MDR, XDR) such as superbugs.  Such as tuberculosis. - Cross Resistance - pathogen can acquire resistance to several antibiotics with a similar chemical structure. Eg. NDM-1 (research more on NDM-1) (issue is that we are losing antibiotics, like the beta lactam ring). NDM-1 can make antibiotics resistance to certain rings like beta lactam ring. - we are making less drugs due to antibiotic resistance. Generations of derivaties antibotics: we went from penicillin N to amoxicillin to piperacilin. Retarding Resistance - Limit use of antimicrobials to necessary cases. - High concentrations of drug and long treatment - Use antimicrobial agents in combination - Development of new variations of existing drugs o Novel side chains added to original molecules. IE. Glycylcyclines is a newly approved antibiotics - Development of drugs for new targets - Better diagnostic tools (DNA based) Diversity of Prokaryotes Bacteria’s have different shapes:  bacillus (rod like) for ex. E.coli  spirillum (spirial)  coccus (spherical) Environmental Conditions (ex. Here are of archea) Ex of eukaryotes are animals, plantes and unicellular  Temperature o grows best below 20C psychrophiles (for ex. maple leaf ) o grows best between 20-50C  mesophiles o grows best above 50C thermophiles (loves hot temperature)  pH (acid or base environment) o grows well at pH of 1-2 (acidic)  acidophiles (H.pylori) o grows best near neutral pH  Neutrophile o grows well at pH as high as 9 (basic) Alkaliphile  Water o Most bacteria require a minimum moisture o Spores: near absence of moisture  Salt o Most bacteria require a moderate level of salt o Some cells can exist in very high salt concerntration (halophiles)  Oxygen Avaliability o Require oxygen for growth  aerobic o Require lack of oxygen for growth  anaerobic  Nutrient Availability o Most microorganisms require organic and inorganic nutrients to grow and survive o Cyanobacteria grow in the absence of key nutrients. Ex. Can convert co2 from air into organic cellular molecules. The evolution of life on earth Origin of life: it started with universal ancestor bacteriaarchaea (bacteria and archea are unicellular) eukarya (animal and plants) Archaea - morphologically, the two kingdoms of prokaryotes appear similar. However, they have major biochemical differences such as their cell walls no peptidoglycan in archea) - most archaea live in extreme envronments o Thermoacidophiles: you can find them in the bottom of the ocean
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