Treatment For Infections Flashcards
Define osmotic pressure
O.P of a solution is the external pressure that must be applied to prevent the movement of solvent via osmosis
What is the unit for O.P?
Osmoles (Osm)
Milliosmoles (mOsm)
What’s the different bw osmolality and osmolarity?
Osmolality: no. Of osmoles/ kg of solvent ie water
Osmolarity: no. Of osmoles/L of solution
What’s the normal osmolality for blood?
285 mOsmo/kg
Define anti microbial agent
Chemicals which kill (bactericidal) / inhibit (bacteriostatic) microbial growth in or on a body surface
Topical- kill bac on surface
Oral, iV- kill bac inside body
What are the three sources of antimicrobials? And which is the most common one?
Micro organism
Synthesis (chloramphenicol)
Semi synthesis* (penicillin=b lactams)
What type of bacteria does antimicrobial agent work best on? (Actively dividing or dormant, latent?)
Actively dividing bacteria
What are the ideal properties of antibiotics?
Antimicrobial properties for example
Specific, selective, cidal, slow emergence of R
Pharmacological activities: Non toxic to host Long half life Low plasma protein binding Good tissue distribution Oral &parental No interactions w other drugs
Name the four main sites of action of antibiotics on a bacteria
Cell wall*
Cell mem
Nucleic acid synthesis
Protein synthesis - bacteriostatic
Name two cell wall synthesis inhibitors
B lactams* :penicillin, cephalosporins, carbapenems, monobactams
Glycopeptides : vancomycin, teicoplanin
Describe the MOA for b lactams e.g. Amoxicillin (penicillin)
1 bind and inhibit action of penicillin binding proteins (PBPs) - transpeptidases–> prevent Xlinking bw neighbouring PG–>cell lysis
2 get incorporated into peptide side chain, prevent X linking - cell lysis
3 stimulate autolysins- break down own cell wall- lysis
Describe the MOA for glycopeptides e.g. Vancomycin and teicoplanin
1 bind to D ala, D ala on peptide side chain of monomer
(NAG+NAM+side chain) on outer surface of cell wall
2 prevent glycosylase enzyme from adding PG monomer onto PG chain
3 prevent X linking
Name 2 bacterial cell mem inhibitors
Polymyxins E(colistin)
Lipopeptides: daptomycin (cubicin)
Describe the MOA for polymyxin C (colistin)
Works on G-ve bac only Bind to lipid A of PLS on the OUTER MEM Break down permeability of outer mem Through to cyto Leakage of cyto content
Name 2 drugs that classified as fluoroquinolones
Ciprofloxacin
Levofloxacin
What’s the name for type of AB that can inhibit NA replication/ translation
Fluoroquinolones
F group makes quinolone more active
Describe the MOA for fluoroquinolones
1 inhibit bacterial DNA replication via -binding to DNA gyrase and /or type 4 topoisomerases
DNA gyrase removes DNA supercooled ahead of replication fork
Topoisomerase 4 separate 2 new DNA strands after replication
2 this inhibits DNA rep and packaging of DNA within bac cell
3 cell lysis
Name 2 bacterial cell protein inhibitors
Aminoglycosides
Tetracycline
An example drug that’s classified as aminoglycoside
Gentamicin
Describe the structure and binding sites of a bacterial ribosomome
50s and 30s subunits
50s: 23S & 5S rRNA + protein
30s: 16S rRNA + protein
A acceptor site
P peptide site
E exit site
MOA for aminoglycoside e.g. Gentamicin
1 bind IRREVERSIBLY to the A site on 16s rRNA in 30s subunit
2 causes misreading of codons along the mRNA
3 wrong AA in sequence
4 interferes w translocation of tRNA from A site to P site
5 indirectly disrupt mem permeability
Bactericidal!!! Not common
MOA for tetracycline e.g. Doxycycline
Bind REVERSIBLY to A site Inhibit binding of tRNA to A site Inhibit protein synthesis Target also present in human cells, however better uptake by bacterial cells Bacteria static
What are the 4 classes of b lactamase?
Class A : penicillinases e.g. TEM1,2
Class B : Metallo- b lactamases
Class C : cephalosporinase
Class D : ESBL hydrolysing b lactam AB w more variable structures
What are the side effects of ciprofloxacin?
GIT - c.difficile
DDI (drugs that are metab by CYP450 in liver)
Cartilage (young)/ tendon (old) damage
Rash, photosensitivity
What type of inhibitor is rifamycin? Give a common example
Rifampicin
RNA polymerase inhibitor -bacterialcidal
Uses of rifamycin
Is it a semi/fully synthetic AB?
1st line TB along w other AB to reduce R
Prophylactic against meningitis
Infections of prosthetic joints
Endocarditis
Describe how metronidazole work
Inactive prodrug get into bac cell
Activated by bac enzyme
Used to treat infections caused by ANAEROBES e.g. C DIFFICILE
Some genital tract infections SSTI dental infections
Active metab cause DNA strand breakage
How does rifampicin get excreted?
Via bile
Who collects data on AB and infections?
What kind of report do they provide
ECDC EARS ESAC Surveillance of R of AB Consumption
U.K. Five year AMR strategy
Year
Main points
2013-2018
- Improve knowledge on AMR
- Stewed the effectiveness of existing AB
- Develop new AB
IV/ oral switch criteria
1 patient improving 2 SER CRP WBC normalise 3 review after 48h 4 able to take oral 5 does Not have deep seated infection e.g. Endocarditis, brain abscess, prosthetic join inf
AB prescribing and stewardship 5 competencies
1 infection prevention and control 2 ABR and AB
3 prescribing Ab
4 AB stewardship
5 learning and monitoring
