Microbiology Flashcards
What are the three ways an antibiotic can act on the cell?
Act on the bacterial cell wall
Affecting the bacterial ribosome
Acting on bacterial DNA directly
Penicillins act to break the bacterial strand of DNA - True/False?
False - they act to inhibit cell wall synthesis
What facilitates the action of penicillins?
b-lactam ring
What are the benefits of using penicillin?
safe to use in healthy and pregnant patients
What are the disadvantages of penicillins?
Hypersensitivity in some patients
Rapid excretion requires more frequent dosing
What species is penicillin effective on?
Clostridium Streptococcum Bacteroides Neisseria S. Aureus
Clostridium
Gram +
Streptococcus
Gram +
Bacteroides
Gram -
Neisserin
Gram -
Staphylococcus
Gram +
What types of bacteria is Flucloxacillin effective against?
Gram +
Flucloxacillin is narrow spectrum - True/False?
True
What types of bacteria is flucloxacillin used against?
staphylococci
streptococci
What sort of infection is flucloxacillin used for?
skin infection, wound infection, cellulitis
For what type of infection is Flucloxacillin the drug of choice?
Staphylococcus aureus
What are the benefits of amoxicillin?
safe and well tolerated
What are the disadvantages of amoxicillin?
less effective in bacteria which have developed b-lactamase
What species is amoxicillin effective against?
Clostridium Streptococcus Enterococcus E.coli Haemophilus influenzae Neisseria Bacteroides
Enterococcus
Gram +
E.Coli
Gram -
Haemophilus Influenzae
Gram -
Neisseria
gram -
What is co-amoxiclav?
combined antibiotic, amoxicillin and clavulanic acid
What is clavulanic acid?
b-lactamase inhibitor
Which bacteria can co-amoxiclav treat that amoxicillin cannot?
staphylococcus
improves outcomes for other species
Piperacillin/Tazobactam?
Combination of antibiotic and tazobactam b-lactamase inhibitor
What does piperacillin/Tazobactam treat?
almost anything apart from MRSA and resistanct coliforms
How do cephalosporins act?
inhibit cell wall synthesis by preventing cross linking of peptidoglycan
What is the disadvantage of cephalosporins?
significantly affect normal gut flora
Give a first gen cephalosporin
cefalexin -UTI
2nd Gen cephalosporin
cefuroxime
3rd Gen Cephalosporin
cefixime - Gonnorhoea
ceftriaxone - meningitis
4th Gen Cephalosporin
Ceftazidime - pseudomonas
Glycopeptides
Vancomycin
Teicoplanin
How do glycopeptides work?
inhibit cell wall synthesis but by binding growing pentapeptide chains and preventing cross-linking
What are the issues with glycopeptides?
Has to be given IV
Can be toxic to renal failure patients
Not absorbed from the gut
What infection can vancomycin be used to treat?
C.diff
What forms of antibiotics affect protein synthesis?
macrolides
tetracyclines
aminoglycosides
How do antibiotics affecting proteins synthesis work?
attach to bacterial ribosomes - bacteriostatic not bacteriacidal
What is the exception to the bacteriostatic rule in protein synthesis?
aminoglycosides where binding the ribosome is lethal
Examples of macrolides
erythromycin
clarithromycin
azithromycin
How are macrolides excreted?
liver –> biliary tract –> gut
What are macrolides particularly useful for treating?
intracellular bacteria because they are lipophillic and can pass through cell membrane
Legionella
Which macrolide is safe in pregnancy?
erythromycin
Where are macrolides useful?
where bacteria do not have a proper cell wall
Which species do macrolides work well on?
clostridium streptococcus enterococcus staphylococus MRSA Neisseria Haemophilia influenzae Bacteroides
Aminoglycoside
Gentamycin
What do aminoglycosides mostly act on?
Gram -, aerobic organisms, coliforms, pseudomonas
What are the disadvantages of aminoglycosides?
narrow therapeutic index
damage to kidneys
damage to VIII cranial nerve - deafness and balance issues
Which species do aminoglycosides act on?
MRSA S.Aureus Pseudomonas aeruginosa E.coli Neisseria
Tetracycline in Tayside
Doxycycline
What is doxycycline useful for treating?
atypical pneumonia
chest/skin infections in patients who are penicillin allergic
