Antibiotics and Antibiotic Resistance Flashcards
What are 3 key differences between a bacterial cell and a mammalian cell?
B has a cell wall and no nuclear membrane, 30s 50s ribosome.
M has no cell wall a nuclear membrane and 40s 60s ribosome
What are the obvious target sites?
Cell wall and ribosomes
What does Bacteria require to grow?
Optimum temp and PH, nutrients, atmospheric conditions
What are the 3 types of atmoshpheric conditions?
Aerobic
Anaerobic
Facultative
What is Aerobic?
Any organism that doesnt need O2 to grow
What is Anaerobic?
which grows in the present of air or needs O2
What is Facultative?
Can use oxygen but also has anaerobic methods of energy production
What are the 3 main groups of bacteria?
Gram Stained (+-)
Acid-fast bacilli (myobacteria)
Atypicals
What is the difference between Gram positive and Gram negative?
Gram negative is red and has lipophilic cell membrane
Gram positive is violet and has peptidoglycan cell wall
What type of antiobiotics are used for Gram stains?
Amoxicillin, Cefuroxime
Cefalexin
What are some Anti-anaerobe agents?
Metronidazole
Piperacillin
Co-amoxivclav
What are some Anti-atypical agents?
Monocycline, Erythromycin, Moxifloxacin
What are the portals of entry for microorganisms into the body?
Skin
GI tract
Respiratory tract
Urinogenital
What is antibiotics?
A medicine that inhibits the growth of or destroys microorganisms
What is Antibacterial?
Destructive or inhibits growth of bacteria
What is Antimicrobial?
Destroy or inhibit growth of pathogenic micro-organisms
What is Disinfectant?
Chemical liquid that destroys bacteria
What is bactericidal?
Drug which kills bacteria or capable of murder
What is bacteriostatic?
Capable of inhibiting reproduction of bacteria
What is the site of action for Penicillins, Glycopeptides?
Bacterial cell wall
What agent can be used for Cell Membrane?
Daptomycin
What agent can be used for Ribosomes?
Tetracyclines, Fucidic acid
What agent can be used for RNA synthesis?
Rifamycines
What agent can be used for Folate metabolism?
Sulphoamides
What agent can be used for DNA synthesis?
Nitrofurans
What are Beta-lactams?
Interfere with cross linkage of peptidoglycans and bactericidal
What are Glycopeptides?
Inhibit peptidoglycan formation
What does Penicillin contain?
Bacteria with 8 penicillin-binding proteins
How does penicillin work?
Penicillin modify PBP function because of structural similiarity to D-alanine residue of peptidoglycan
What effect does Penicillin have on bacteria?
Weaken the cell wall and act on biosynthesis and cell division - depend on nature of b-lactam ring
What drugs have a beta lactam ring?
Penicillin, Carbapenems, Clavams
What does Glycopeptides do?
Interfere with peptidoglycan formation by preventing joining of n-acetylglucosamine and acid dimers
How do Glycopeptides work?
Molecules too large to penetra outer membrane, used aggainst streptococci
How does Vancomyin work?
Prevents phospholipid carrier release prevent chain elongation
What is the effect of Lipopeptide daptomycin (antiobiotic) acting on Membrane?
Depolarises cell membrane, poor lung penetration, bactericidal to g+
What is the effect of Polymixins colistin (antiobiotic) acting on Membrane?
Affects affinity for membrane in G - bacilli
also bactericidal
How does Tetracyclines Antibacteria inhibit ribosomes?
Binds to 30s ribosome and block attachment of tRNA and addition of AA - inhibits binding complex
How does Aminoglycosides Antibacteria inhibit ribosomes?
Interfere with mRNA attachment to the ribosome
How does Chloramphenical Antibacteria inhibit ribosomes?
Binds to 50s ribosome and interferes with binding of AA
How does Macrolides and Lincosamides Antibacteria inhibit ribosomes?
Attach to 50s unit causing termination of growing protein
How does Linezolid Antibacteria inhibit ribosomes?
Binds to 23s RNA of 50s and prevents formation of functional 70s for protein synthesis
How does Quinolones Affect nucleic acid synthesis?
Functions by selectively inhibiting DNA gyrase and inhibits cell division
How does Rifampicin Affect nucleic acid synthesis?
It inhibits DNA dependent RNA polymerase by forming stable complex with enzyme
How does Metronidazole Affect nucleic acid synthesis?
Binds to bacterial DNA leads to strand breakage
How does Trimethoprim interfere with a metabolic pathway?
Inhibits dihydrofolate reductase - key stage of develop nucleic acids - blocks active form of folic acid
Why is Antibiotics important?
Infectious disease is common and fatal
Antimicrobial resistance
Hospital infections
Surgery and Chemotherapy
What is antimicrobial resistance?
Loss of effectiveness of any anti-infective medicine include anti-medicines - common bacteria of common infections
What is Intrinsic resistance?
Entire species resistant BEFORE any antibiotic introduced - lack penetration through cell wall, susceptibility to produce enzymes
What are Examples of Intrinsic resistance?
Gentamicin step pyogenes
Polymixin stapj aureus
What are 3 types of gene transmission?
Conjugation
Transduction
Transformation
What is conjugation?
Plasmids move from one bacteria to another
What is transduction?
Phages move between bacteria sometimes carry genes
What is transformation?
Take up DNA from solution
What is Antibiotic inactivation?
Bacteria acquire genes encoding enzymes that inactive antibiotics e.g B-lactamases
What are the mechanisms for resistance?
Impermeability of the cell wall, Active efflux pumps throw antibiotic out cell, altered targets, bypass steps, hyperproduction of enzymes
