week 1 Flashcards
define antibiotics?
chemical products of microbes that inhibit or kill other organisms
what is antimicrobial agents? Give examples
it is a umbrella term of agent that kills a wide rang of different things. Antibacterial, antifungal and antiviral
what are the different types of antimicrobial agents?
antibiotics, synthetic compounds with similar affects or semi synthetic compounds
what are semisyntheti compounds?
are modified versions of antibiotics.
They have different antimicrobial activity/spectrum, pharmacological properties or toxicity
what is Bacteristatic and what does it affect?
it inhibits bacterial growth –> stops the growth of bacteria and therefore allows the human immune system to destroy the bacteria.
It is a protein synthesis inhibitor
what is bacteriacidal? What does it affect?
it kills the bacterial and affect cell wall-active agent
what is minimum inhibitory concentration MIC?
Minimum concentration of antibiotic at which visible growth is inhibited
can someantibiotic act as both bacteristatic and bacteriacidal? Explain
yes at low concentration the antibiotic can be bacteristatic but then at high become bacteriacidal
what is Synergism?
the activity of 2 antimcrobials together is greater than activity given seperately
What is antagonism?
when one agent diminishes the activity of another?
what is Indifference in terms of antibiotics?
the addition of antibiotic have no affect on the other antibiotic activity
what is the treatment of streptococcal endocarditis? What type of interaction is it?
β-lactam/aminoglycoside combination therapy
Synergism interaction
what are antibacterial target types ?
molecules, structures and enzymes?
what are structures?
things bigger than molecules
what are the two types of selective toxicity?
Tackle a Target not present in human host but in the bacteria
Tackle a Target significantly different in the bacteria compared to the human host
what are the main 5 antibacterial targets?
Cell wall Protein synthesis DNA synthesis RNA synthesis Plasma membrane
what is bacterial cell wall made up of?
peptidoglycan
do animals have cell wall?
no
what type of bacteria have cell wall?
both gram positive and gram negative bacteria have cell walls
what is peptidoglycan made up of?
Polymer of glucose-derivatives, N-acetyl muramic acid (NAM) and N-acetyl glucosamine (NAG)
why is antibiotics targeting cell walls so effective?
all bacteria have cell wall while humans do not
why do bacteria need cell wall?
Need cell wall for protection and is constantly remolding –> essential for their life
what are the 2 classes of cell wall inhibitors?
B lactams and Glycopeptides
what is the most common type of B lactams?
penicillin
what was the first true B lactam antibiotics?
Benzylpenicillin ( Penicillin G)
what do all B lactam antibiotics contain in their structure?
B lactam ring
what does B lactam ring contain?
Four-membered ring structure (C-C-C-N)
Structural analogue of D-alanyl-D-alanine
how do B lactam antibiotics work?
They intefere with penicillin binding proteins. These are Transpeptidases enzymes that are invovled in peptideoglycan cross linking ( cell walls)
what is the first oral B lactam?
phenoxymethyl penicillin (penicillin V).
what was the first antibiotic to be active against the family of Enterobacteriaceae?
Ampicillin
what two B lactam can only be given parenterally?
Benzylpenicillin and ampicillin
what does parental dosage mean?
are intended for administration as an injection or infusion
what is the oral equivilant of Ampicillin ?
amoxycillin
what is Meticillin ?
anti-staphylococcal penicillin.
what is key about the structure of meticillin?
it has a side chain that prevents the hydrolysis of the drug by staphylococcal b-lactamase
what two drugs have replaced meticillin?
cloxacillin and flucloxacillin
what are the 4 main key antibiotics underneath B lactam antibiotics?
Penicillins
Cephalosporins
Carbapenems
Monobactams
give me examples of penicillin and what is the most common type? What type of spectrum does it have?
Benzylpenicillin,
amoxicillin –> most common
flucloxacillin
Relatively narrow spectrum
give me examples of Cephalosporins and what is the most common type? Does it cover gram negative bacteria?
Cefuroxime–> common
ceftazidime
Broad spectrum
covers gram negative bacteria
give me examples of Carbapenems?
Meropenem, imipenem
Extremely broad spectrum
what type of antibiotics is used when allergic to penicillin? give example of this type of antibiotic? what Type of bacteria is it active too?
Monobactams
type of monovactams is: Aztreonam
Gram-negative activity only
give me examples of glycopeptides antibiotics?
Vancomycin –> more common
teicoplanin
how does glycopeptides work?
Inhibit binding of transpeptidases and thus peptideoglycan cross-linking
what type of bacteria can glycopeptides be active against?
only active against gram positive bacteria.
Because it cannot penetrate the outer membrane porins of gram negative bacteria
what is Ribonucleoprotein complexes main up of?
2/3rds RNA and 1/3rd protein
what is mRNa made up of?
50s (large) subunit and 30s (small) subuinte that combine to form the 70s initation complex
give example of Aminoglycosides
Aminoglycosides
Examples are: Gentamicin, amikacin
how does Aminoglycosides work?
Bind to 30S ribosomal subunit
what is the severe side affect of gentamicin?
it is a nephrotoxic
what is nephrotoxicity?
it is toxic to the kidneys
give examples of Macrolides, Lincosamides, Streptogramins (MLS)
Erythromycin, –> most common type
clarithromycin (macrolides)
what is alternative option to erthromycin?
clindamycin–> less side affects
how does MLS antibiotics work?
Bind to 50S ribosomal subunit1
Blockage of exit tunnel
Inhibit protein elongation –> prevent the addition of more peptides
give examples of tetracyclines?
tetracylcine and deoxytetracycline
how does tetracyclines work?
bind to 30s and prevent the translation of tRNA with rRNA
give examples of Oxazolidinones?
Linezolid
how does Linezolid work?
Inhibits initiation of protein synthesis
Binds to 50S ribosomal subunit
Inhibits assembly of initiation complex
May also bind to 70S subunit
what antibiotic prevents folic acid production?
Trimethoprim and sulfonamides
together what are Trimethoprim and sulfonamides called?
co-trimoxazole
why is folic acid inhibited by antibiotics?
it is a precusor for purin synthesis
what is Trimethoprim?
Dihydrofolate reductase
what does Sulfonamides directly inhibit and why?
Dihydropteroate synthetase because it is the enzyme catalyses the first step in folic acid synthesis.