Antibiotics Flashcards
what are antibiotics and what do they do?
small molecules that kill or inhibit the growth of prokaryotes/bacteria
used to control/limit the impact of bacterial disease
what is antibiotic resistance?
the ability of bacteria to escape the action of antibiotics
what does bacteriostatic mean?
inhibit the growth of bacteria
what does bactericidal mean?
kill the bacteria
antibiotics are not a substitute for what? why?
a non-functional immune system.
As they reduce bacteria to aid in immune response.
what does pharmodynamics of antibiotics mean?
How it kills the target organisms: conc., exposure time …
what does pharmokinetics of antibiotics mean?
How your body deals with and interacts with the drug: absorption, excretion …
describe the ideal antibiotic, 4 things
Minimal toxicity to host
Long half-life -> not having to constantly take it
Appropriate tissue distribution -> goes to the right tissue
No adverse drug interactions or side effects
Antibiotics have selective toxicity -> have targets.
the most successful antibiotics target what?
the cell wall
They inhibit the synthesis of the cell wall, so degradation continues without synthesis resulting in gaps in the cell wall
penicillins are an antibiotic that targets what?
the cell wall
what is the general structure of penicillins?
- Contain B-lactam ring
Can attach different side chains to have different spectrum and resistance to bacteria
are penicillins narrow or broad spectrum antibiotics?
range from narrow to broad
state 3 limitations of penicillins
Allergic
Rapid excretion via kidneys so frequent dosing
Resistance
what are the last line antibiotics?
carbapenems (B-lactam)
what does amoxycillin target?
cell wall
what is the most commonly prescribed antibiotic? why?
amoxycillin
as has broadest spectrum of bacteria it covers
Stable in presence of stomach acid so can be taken at any time (don’t have to eat before)
what does amoxycillin target?
cell walls
what is the structure of amoxycillin?
B-lactam
Penicillin V may be better first choice than amoxycillin. why?
Narrower spectrum
so less impact on GI as does not affect enterococci which is found normally in the GI
what does erythromycin target?
proteins synthesis
what is used for patients who have a penicillin allergy?
erythromycin
what does metronidazole target?
nucelic acid synthesis inhibitor
what is the only antibiotic that can kill both bacteria and protozoa?
metronidazole
which antibiotic is Better under anaerobic conditions so affects anaerobes more effectively
metronidazole
Resistance is extremely rare to which antibiotic?
metronidazole
which antibiotic has adverse reactions with alcohol?
metronidazole
name 2 examples of natural resistance
Target not present or accessible
Persistor cells
what are persistor cells?
metabolically inert the bacteria can persist as antibiotics wont target and degrade it (naturally resistant to antibiotics in this state)
what do persistor cells do?
Enrich the biofilm to be more tolerant to antibiotic
Linked to reinfection
how does acquired resistance occur?
by change to the microbe e.g. mutation
how does acquired resistance spread?
horizontal gene transfer: a resistance gene can be passed between species thus spreading resistance
- Enrich the biofilm with more resistance
broad spectrum antibiotics increase the risk of what?
Clost. Difficile infection in the elderly.
what are the high risk antibiotics for clost. difficile?
4Cs
Cephalosporins
Co-amoxiclav
Ciprofloxacin
Clindamycin
what are the 3 key messages when prescribing antibiotics?
Keep prescribing to a minimum
Consider local measures
Consult guidelines
state 3 antimicrobial drug resistance mechanisms?
altered permeability
inactivation of B-lactam ring by B-lactamases
altered target on cell wall
how does altered permeability cause antimicrobial drug resistance?
Don’t take drug up or is exerted faster than taken up
extended spectrum B-lactamases causes resistance to what antimicrobials?
all penicillins
carbapenemase causes resistance to what antimicrobials
resistant to all penicillins, cephalosporins and carbapenems
why does carbapenemase pose a major healthcare risk?
as carbapenems are the last line antibiotics
what is MRSA?
methicillin resistant S.aureus
what causes MRSA?
altered target on cell wall
MRSA is resistant to what antibiotic?
flucloxicillin (which replaced meticillin)
resistance is rare to what antibiotic? why?
metronidazole
as its inactive till in the cell
resistance to metronidazole is due to what?
possibly having genes that cause resistance
which bacteria is of concern with metronidazole resistance?
prevotella
what is emperic prescribing?
When prescribing don’t know the cause of organism
Site of infection gives clues as to what bacteria is present
targeted prescribing requires testing and checking. when is this used?
When they are not responding as you would expect
what patient considerations are there when prescribing antibiotics?
Allergies
Patient compliance -> following guidelines e.g. child, disability, elderly, dementia, busy so cant fit around meal times etc.
what is the major issue with antibiotics to the patient?
affect on GI tract -> secondary infection due to change in GI environment
Fungi can grow in the absence of bacteria e.g. antibiotic sore mouth (candida albicans)
