Antimicrobials Flashcards
Name the 3 classes of antibiotics which inhibit the bacterial cell wall
penicillins
cephalosporins
carbepenems
vancomycin
which of the bacterial cell wall inhibitors are beta lactam antibiotics?
penicillins
cephalosporins
carbepenems
what is the mechanism of action of penicillin’s, cephalosporins and carbepenems?
inhibits CW biosynthesis
inhibit enzyme involved in transpepidase cross linking reaction, interferes with cell wall biosynthesis as individual chains can not link together
name 5 penicillin’s
end: CILLIN oxacillin ampicillin amoxicillin cloxacillin methicillin
which bacteria are penicillin’s most effective against?
gram +
what mechanism do beta lactam ring antibiotics use?
autolysis
what is the beginning of all the cefhalosporins?
CEF
eg. cephalexin
cefazolin
name 3 carbapenems
end: PENEM
meropenem
ertapenem
imipenem
carbapenems can only be administered by which route?
IV
what is the mechanism of action of vancomycin?
inhibits CW biosynthesis by encapsulating peptide bonds between PG layers to prevent joining
name the 4 classes of antibiotics which inhibit protein synthesis
tetracycline (doxycyclin)
chloramphenicol
aminoglycosides (gentamycin, streptomycin)
macrolides (erythromycin)
describe the mechanism of action of tetracycline (doxycyclin) and aminoglycosides (gentamycin, streptomycin)
bind to and inhibit protein of 30S subunit
describe the mechanism of action of chloramphenicol and macrolides (erythromycin)
binds to and inhibits protein of 50S subunit
which bacteria are antibiotics targeting protein synthesis effective against?
both gram + and - (broad spectrum)
are antibiotics targeting protein synthesis bacteriostatic or bactericidal?
bacteriostatic
are antibiotics targeting CW biosynthesis bacteriostatic or bactericidal?
bactericidal
which class of antibiotics targets DNA systhesis?
fluoroquinolones
name the fluoroquinolones?
end: FLOXIN ciprofloxin norfloxin levofloxin moxifloxin
what are the mechanism of action of fluoroquinolones?
inhibit enzymes (DNA gyrase) which has essential role in DNA replication
which class of antibiotics is effective against intracellular pathogens such as legionella and mycoplasma?
fluoroquinolones
which bacteria are fluoroquinolones effective against?
broad spectrum
what is the mechanism of action of Rifampicin?
inhibits RNA biosynthesis
inhibits bacterial DNA-dependant RNA polymerase
which antibiotics is predominantly used to treat TB?
rafampicin
name three antibiotics which directly inhibit nucleic acid by inhibiting folate biosynthesis?
sulphonamides
trimethoprim
co-trimetoxazole
what is sulphonamides mechanism of action?
analogue of PABA; acts a substrate competion
what is the mechanism of action of trimethoprim?
inhibits dihydrofolate reductase
what is the mechanism of action of co-trimetoxazole?
mix of sulphonamides and trimethoprim
why is folate a good target for antibiotics?
bacteria make folic acid and humans don’t
what antifungals are B1,3- glucan inhibitors?
echinocandins
name 2 echinocandins
end: FUNGIN
casofungin
micafungin
are echinocandins fungicidal or fungiostatic?
fungicidal
what is B1,3- glucan?
allows synthesis of fungal cell wall - essential component and target for most antifungals
what is the mechanism of action of echinocandins
inhibits enzyme B1,3 Glucan synthase thus blocking synthesis of fungal CW
name the three classes of esgosterol inhibiting antifungals
polyenes
azoles
allylamines
name 2 polyene antifungals
amphotericin B
nystatin
what is the mechanism of action of polyenes?
bind to ergosterol in plasma membrane
forms pores in PM which disrupt integrity and cause leakage of cells constituents
how can the severe side effects of polyenes be reduced?
use amphotericin B complex or liposomal
amphotericin B formulations
are polyenes fungicidal or fungiostatic?
fungicidal
name 2 types of azoles
imidazoles
triazoles
name 3 imidazoles
end: AZOLE
miconazole
clotrimazole
ketoconazole
name 3 triazoles
end: AZOLE
fluconazole
voriconazole
itraconazole
what is the mechanism of action of azoles?
inhibit lanosterol C-14 demethylase - a key step in ergosterol synthesis
name 2 allylamines
end: FINE
terbinafine
amorolfine
what is the mechanism of action of allylamines?
inhibits earlier step in ergosterol biosynthesis
which azole is more potent?
triazoles
what is the mechanism of action of flucytosine?
metabolised by fungal cell to 5-fluorourcil which is toxic and inhibits RNA and DNA synthesis
which other antifungal is flucytosine used in combination with?
azoles
