immuno bac Flashcards
(46 cards)
whats prontosil
the first example of a sulphonamide antibiotic
only effetcive with gp bacteria
charateritics
Bacteriostatic.- doesnt kill only stop repliccating
Synthetic
what is it sometimes used with
Trimethoprim called (co-trimoxazole). both have some function
treat
UTIs, RTIs, bacteraemia and prophylaxis for HIV+ individuals.
Bactericidal
kills bacteria.
Bacteriostatic
stops bacteria growing
Antimicrobial
hemical that selectively kills or inhibits microbes (bacteria, fungi, viruses).
Antiseptic
chemical that kills or inhibits microbes that is usually used topically to prevent infection.
what does ab resistance lead to
AB resistance leads to increased mortality, morbidity and cost
Increased time to effective therapy.
Requirement for additional approaches – e.g. surgery.
Use of expensive therapy (newer drugs).
Use of more toxic drugs e.g. vancomycin.
Use of less effective ‘second choice’ antibiotics.
where are Aminoglycosides
Bactericidal.
Target protein synthesis (30S ribosomaml subunit), RNA proofreading and cause damage to cell membrane.
Toxicity has limited use, but resistance to other antibiotics has led to increasing use.
can cause hearing loss
what is Rifampicin
Bactericidal.
Targets RpoB subunit of RNA polymerase.
Spontaneous resistance is frequent.
Makes secretions go orange/red – affects compliance taking long causes
what is Vancomycin
Bactericidal.
Targets Lipid II component of cell wall biosynthesis, as well as wall crosslinking via D-ala residues
Toxicity has limited use, but resistance to other antibiotics has led to increasing use e.g. against MRSA
given intravenously
what is Linezolid
Bacteriostatic.
Inhibits the initiation of protein synthesis by binding to the 50S rRNA subunit.
Gram-positive spectrum of activity.
doesn’t effect gn
Daptomycin
Bactericidal. Targets bacterial cell membrane. Gram-positive spectrum of activity. Toxicity limits dose. can't target lps on gn given intervenosly
Beta-lactams
Interfere with the synthesis of the peptidoglycan component of the bacterial cell wall.
Examples include Penicillin and methicillin.
Bind to penicillin-binding proteins.
PBPs catalyse a number of steps in the synthesis of peptidoglycan.
inhibite biosythesis of cell wall
Antibiotics target many different bacterial processes and are selectively toxic
they inhibit process in bacterial cell not in human cells
The large number of differences between mammals and bacteria result in multiple targets for antibiotic therapy – selective toxicity
What is unique to bcteira
peptidoglycan wall
lpa
Macrolides
treats gonococal
Gram-positive and some Gram-negative infections.
Targets 50S ribosomal subunit preventing amino-acyl transfer and thus truncation of polypeptides.
preventing growth
Quinolones
Synthetic, broad spectrum, bactericidal.
Target DNA gyrase in Gm-ve and topoisomerase IV in Gm+ve. dna damage and death of organism
against gonnocal and lung
Breakpoint
(clinically-achievable concentration)
if bacteria can grow at that point or higher than reistant, if less that suseptible
what does routine use of penicllin provide
Routine use of penicillin provided selective pressure for the acquisition and maintenance of resistance genes.
how does antiboitic resistance occur
Altered target site.
Inactivation of antibiotic.
Altered metabolism.
Decreased drug accumulation.
what is altered target site
Can arise via acquisition of alternative gene or a gene that encodes a target-modifying enzyme.
Methicillin-resistant Staphylococcus aureus (MRSA) encodes an alternative PBP (PBP2a) with low affinity for beta-lactams.
Streptococcus pneumoniae resistance to erythromycin occurs via the acquisition of the erm gene, which encodes an enzyme that methylates the AB target site in the 50S ribosomal subunit.
Inactivation of antibiotic
Enzymatic degradation or alteration, rendering antibiotic ineffective.
