micro- antimicrobial agents Flashcards
definition of an antibiotic
the products of microbes that in dilute solution inhibit or kill organisms
what might we do to naturally occurring antibiotics
we may modify them to give synthetic derivatives
define antimicrobial agents
include antibiotics and synthetic compounds that have the same effect
what are the two types of antibiotics
bacteriostatic
bacteriocidal
what does bacteriostatic mean
inhibit microbes so growth stops
what does bacteriocidal mean
kill microbes
give an example of a bacteriocidal antibiotic
gentamicin
give an example of a bacteriostatic antibiotic
chloramphenicol
how do we determine which drug is used to treat which bacteria
susceptibility testing
using isolated bacteria- different drug discs
epsilon testing
what do we look for when susceptibility testing and epsilon testing
the largest zone of inhibition
and also if there is any mutant species as there is no zone of inhibition
define minimum inhibitory conc
Lowest conc of antibiotic that prevents visible growth of a particular bacterium
define minimum bactericidal conc
Lowest conc of antibiotic that kills a specific bacterium
determined using dilution methods
what is the issue with dilution methods
time consuming- as need to make the correct dilution factor
what is selective toxicity
the idea that bacteria have a different metabolism than humans and therefore the antibiotics will act on bacteria but not humans
what is the issue with selective toxicity
doesn’t always work eg
a penicillin allergy is due to the thiazolidine ring
but the B lactam ring also in penicillin is the thing that gives the antibiotic activity
which microbes metabolism is most similar to humans
fungi and protozoa
why can we not use antibiotics on a virus
as a virus relies completely on the human host cell to replicate
what is the main issue with antiviral, anti fungal and anti protists drugs
more limited in their scope and more toxic to humans
what are some key points in the HIV virus replication cycle
- Entry
- Uncoating
- Reverse transcription
- Integration
- Protease inhibition
- Virus replication and assembly
Virus release
what does antisense RNA do
used to inhibit transcription factors
describe antisense RNA
short sequence of RNA that compromises the reverse of an MRNA
therefore binds to the MRNA and prevents translation
what treatment and infection is given for influenza A
amantadine
rimantadine
what is amantadine and rimantadine used for
the treatment and prevention fo influenza A
how does amantadine and rimantadine work
by targeting entry and uncoating steps
how does acilovir work
a nucleoside analogue that treats herpes simplex and varicella zoster virus
what antimicrobial agent treats herpes simplex and varicella zoster virus
acilovir
what is gancylovir
derivative of acilovir
what tx is against cytomegalovirus
gancylovir
what is ribavirin against
broad spectrum to treat respiratory syncytial virus
which tx is for respiratory syncytial virus
ribavirin
describe zidovudine and lamivudine
reverse transcriptase inhibitors
give examples of some reverse transcriptase inhibitors
zidovudine
lamivudine
describe nelfinavir
is a protease inhibitor that can hydrolyse polyproteins produced by viruses
give an example of a protease inhibitor
nelfinavir
what does HAART stand for
highly active antiretroviral therapy
what is HAART used for
pts with aids
describe tamiflu and relenza
neuraminidase inhibitors
what do neuraminidase inhibitors do
prevent the release of viruses from infected cells
give examples of anti fungal agents
nystatin
what is nystatin used for
oral and genital candida infections
what are polyenes
act by binding with sterols in eukaryotic membranes causing destabilisation
what is the issue for amphotericin B
potentially toxic to humans
given with a second anti fungal/suspension
administered with 5- flucytosine
describe 5 flucytosine
Synthetic pyrimidine that is metabolised in fungi to 5 fluorouracil and active against pathogenic yeasts
It interferes with the synthesis of nucleic acids
describe the azole group
large group that inhibit ergosterol synthesis leading to membrane leakage
what are the two groups of azaleas
imidazoles
triazoles
give examples of imidazole
micronazole
chotrimazole
what is the issue with micronazole
too toxic to use systemically but can be used topical
give examples of triazoles
flucanazole, itraconaole
which antifungal agent is used against yeast
flucanazole
what is fluconazole used for
yeast infections
what is terbinafine used for
used for skin and nail infections
what tx can be used for skin and nail infections
terbinafine
what is griseofulvin
a true antibiotic used for ringworm and other fungal infections of skin and nails
what tx can be used for ringworm or skin and nail infection
griseofulvin
give some examples of antiprotist agents
chloroquine
mefloquine
how does metronidazole work
targets DNA and membrane integrity
what does metronidazole treat
anaerobic bacteria
T vaginalis
what do we use for anaerobic bacteria and T vaginalis
metronidazole
what does bacitracin
interferes with the bacterial cell well
give examples of cell wall synthesis inhibitors
cycloserine
B lactams
glycopeptides
what do cycloserine, B lactams and glycopeptides
cell wall synthesis inhibitors
give examples B lactam antibiotics
monobactams
cephalosporin
what is monobactams against
gram -ve bacteria
which agents can affect membrane integrity
Polymyxins
Metronidazole
Gramicidins
which agents affect DNA metabolism
folic acid
trimethoprim
which agents affect DNA
Metronidazole
levofloxacin
ciprofloxacin
nalidixic acid
which agents affect protein synthesis
tetracycline
chloramphenicol
macrolides
aminocycosides
give examples of aminoglycosides
streptomycin
getamycin
what are some side effects of aminoglycosides
streptomycin
gatamycin
which agents are against RNA synthesis
rifampicin
streptomycin
what does rifampicin do
inhibits bacterial RNA polymerase
used to treat TB
prophylaxis of meningitis
